Taking enough omega-3 fatty acid supplements to change the balance of oils in the diet could slow a key biological process linked to aging, new research suggests.

The study showed that most overweight but healthy middle-aged and older adults who took omega-3 supplements for four months altered a ratio of their fatty acid consumption in a way that helped preserve tiny segments of DNA in their white blood cells.

These segments, called telomeres, are known to shorten over time in many types of cells as a consequence of aging. In the study, lengthening of telomeres in immune system cells was more prevalent in people who substantially improved the ratio of omega-3s to other fatty acids in their diet.

Omega-3 supplementation also reduced oxidative stress, caused by excessive free radicals in the blood, by about 15 percent compared to effects seen in the placebo group.

"The telomere finding is provocative in that it suggests the possibility that a nutritional supplement might actually make a difference in aging," said Jan Kiecolt-Glaser, professor of psychiatry and psychology at Ohio State and lead author of the study.

In another recent publication from this study, Kiecolt-Glaser and colleagues reported that omega-3 fatty acid supplements lowered inflammation in this same group of adults.

"Inflammation in particular is at the heart of so many health problems. Anything that reduces inflammation has a lot of potentially good spinoffs among older adults," she said.

Study participants took either 2.5 grams or 1.25 grams of active omega-3 polyunsaturated fatty acids, which are considered "good fats" that, when consumed in proper quantities, are associated with a variety of health benefits. Participants on the placebo took pills containing a mix of oils representing a typical American's daily intake.

The researchers say this combination of effects suggests that omega-3 supplements could represent a rare single nutritional intervention that has potential to lower the risk for a host of diseases associated with aging, such as coronary heart disease, Type 2 diabetes, arthritis and Alzheimer's disease.

The study is published online and scheduled for later print publication in the journal Brain, Behavior, and Immunity.

Participants received either the placebo or one of the two different doses of omega-3 fatty acids. The supplements were calibrated to contain a ratio of the two cold-water fish oil fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), of seven to one. Previous research has suggested that EPA has more anti-inflammatory properties than DHA.

In the case of fatty acids, omega-3 supplementation alone doesn't tell the whole story of how this dietary change can affect health, explained Martha Belury, professor of human nutrition at Ohio State and a co-author of the study. Also important is the ratio of omega-6 fatty acids to omega-3 fatty acids that are present in a person's blood.

Omega-6 fatty acids come from vegetable oils, and since the 1960s, research has suggested that these oils, too, can help protect the cardiovascular system. However, the typical American diet tends to be heavy on omega-6 fatty acids and comparatively low in omega-3s that are naturally found in cold-water fish such as salmon and tuna. While the ratio of omega-6 to omega-3 fatty acids averages about 15-to-1, researchers tend to agree that for maximum benefit, this ratio should be lowered to 4-to-1, or even 2-to-1.


The long chains - or bigger molecules - that make up EPA and DHA fatty acids are believed to be the secret to their effectiveness, Belury said.

Both groups of participants who took omega-3 supplements showed, on average, lengthening of telomeres compared to overall telomere effects in the placebo group, but the relationship could have been attributed to chance. However, when the researchers analyzed the participants' omega-6 to omega-3 ratio in relationship to telomere lengthening, a lower ratio was clearly associated with lengthened telomeres.

"The idea we were looking at with the ratio of omega-6 to omega-3 fatty acids was an increase in the denominator to make the ratio smaller. In the United States, we need to focus on the omega-3 part because we don't get enough of those," Belury said.

The researchers also measured levels of compounds called F2-isoprostanes to determine levels of oxidative stress, which is linked to a number of conditions that include heart disease and neurodegenerative disorders. Both omega-3 groups together showed an average overall 15 percent reduction in oxidative stress compared to effects seen in the placebo group.

When the scientists revisited their earlier inflammation findings, they also found that decreases in an inflammatory marker in the blood called interleukin-6 (IL-6) were associated with telomere lengthening. In their earlier paper on omega-3s and inflammation, they reported that omega-3 supplements lowered IL-6 by 10 to 12 percent, depending on the dose. By comparison, those taking a placebo saw an overall 36 percent increase in IL-6 by the end of the study.

"This finding strongly suggests that inflammation is what's driving the changes in the telomeres," Kiecolt-Glaser said.

Telomeres are a hot topic in science, and their tendency to shorten is associated with such age-related problems as heart disease and early mortality. These short fragments of DNA act as caps at the end of chromosomes, and can be likened to the protective plastic at the end of a shoelace.

"If that plastic comes off, the shoelace unravels and it doesn't work anymore," said study co-author Ron Glaser, professor of molecular virology, immunology and medical genetics and director of the Institute for Behavioral Medicine Research (IBMR) at Ohio State. "In the same way, every time a cell divides, it loses a little bit of its DNA at the ends, and over time, that can cause significant problems."

Kiecolt-Glaser noted that this population was disease-free and reported very little stress. The study included 106 adults, average age 51 years, who were either overweight or obese and lived sedentary lives. The researchers excluded people taking medications to control mood, cholesterol and blood pressure as well as vegetarians, patients with diabetes, smokers, those routinely taking fish oil, people who got more than two hours of vigorous exercise each week and those whose body mass index was either below 22.5 or above 40.

"People who are less healthy than this group, and especially those who experience chronic stress, may gain even more benefits from omega-3 supplementation," she said.
Source: Brain, Behavior, and Immunity

Arginine therapy may be a safe and inexpensive treatment for acute pain episodes in patients with sickle cell disease, according to results of a recent clinical study. The study was the first randomized placebo-controlled study to demonstrate benefits of arginine therapy in children with sickle cell disease hospitalized for severe pain.

Sickle cell disease is an inherited condition in which the body makes red blood cells containing abnormal hemoglobin, the protein that carries oxygen from the lungs to other cells in the body. This abnormal hemoglobin (hemoglobin S) causes red blood cells to distort into a sickle, or crescent shape that often blocks blood flow in small blood vessels, leading to pain and organ damage.

An acute deficiency of nitric oxide in sickled red blood cells contributes to the episodes of blocked vessels and pain. Since the amino acid arginine is a building block of nitric oxide, researchers hypothesized that arginine could be a beneficial treatment for pain related to sickle cell disease.

Previous research found that a single dose of arginine given to sickle cell patients with acute pain episodes resulted in a significant dose-dependent increase in plasma nitric oxide.

Building on that knowledge, the current research study was a randomized, double blind clinical trial of 38 children with sickle cell disease hospitalized for 56 episodes of pain. The research team discovered a 54 percent reduction in the use of pain medication and significantly lower pain scores at hospital discharge in those treated with arginine over those receiving placebo.


The results were published in the journal Haematologica. First author was Claudia R. Morris, MD, assistant professor of pediatrics at Emory University School of Medicine. She conducted the study while in her previous position at Children's Hospital and Research Center in Oakland, CA, with senior author Elliott P. Vichinsky, MD.

"Episodes of pain due to vaso-occlusion are the leading cause of hospital admission and emergency room visits and are associated with increased mortality, yet there is no effective therapy targeting the underlying cause," says Morris. "Treatment consists only of symptom relief with pain medicines and hydration. There is an urgent need for new therapies for acute sickle cell pain, and a greater than 50 percent reduction in use of pain medication was a remarkable finding."

The study found no problems with safety in the use of arginine therapy. Although the treatment did not result in a significantly shorter length of stay in the hospital, the researchers believe delivering the study drug as early as possible in the emergency department or clinic may have a greater impact on length of stay, since many patients received their first dose of medication more than 24 hours after presenting at the hospital.

A large, multi-center trial is warranted in order to confirm these observations and test the effects of delivering the therapy sooner, they note in the published paper.
Source:

Emory Health Sciences

Vitamin B12 is a nutrient that helps keep the body's nerve and blood cells healthy and helps make DNA, the genetic material in all cells. Vitamin B12 also helps prevent a type of anemia called megaloblastic anemia that makes people tired and weak.

Two steps are required for the body to absorb vitamin B12 from food. First, hydrochloric acid in the stomach separates vitamin B12 from the protein to which vitamin B12 is attached in food. After this, vitamin B12 combines with a protein made by the stomach called intrinsic factor and is absorbed by the body. Some people have pernicious anemia, a condition where they cannot make intrinsic factor. As a result, they have trouble absorbing vitamin B12 from all foods and dietary supplements.
Table of Contents

    What is vitamin B12 and what does it do?
    How much vitamin B12 do I need?
    What foods provide vitamin B12?
    What kinds of vitamin B12 dietary supplements are available?
    Am I getting enough vitamin B12?
    What happens if I don't get enough vitamin B12?
    What are some effects of vitamin B12 on health?
    Can vitamin B12 be harmful?
    Are there any interactions with vitamin B12 that I should know about?
    Vitamin B12 and healthful eating
    Where can I find out more about vitamin B12?
    Disclaimer

How much vitamin B12 do I need?

The amount of vitamin B12 you need each day depends on your age. Average daily recommended amounts for different ages are listed below in micrograms (mcg):
Life Stage     Recommended Amount
Birth to 6 months    0.4 mcg
Infants 7–12 months    0.5 mcg
Children 1–3 years    0.9 mcg
Children 4–8 years    1.2 mcg
Children 9–13 years    1.8 mcg
Teens 14–18 years    2.4 mcg
Adults    2.4 mcg
Pregnant teens and women    2.6 mcg
Breastfeeding teens and women    2.8 mcg
What foods provide vitamin B12?

Vitamin B12 is found naturally in a wide variety of animal foods and is added to some fortified foods. Plant foods have no vitamin B12 unless they are fortified. You can get recommended amounts of vitamin B12 by eating a variety of foods including the following:

    Beef liver and clams, which are the best sources of vitamin B12.
    Fish, meat, poultry, eggs, milk, and other dairy products, which also contain vitamin B12.
    Some breakfast cereals, nutritional yeasts and other food products that are fortified with vitamin B12. To find out if vitamin B12 has been added to a food product, check the product labels.

What kinds of vitamin B12 dietary supplements are available?

Vitamin B12 is found in almost all multivitamins. Dietary supplements that contain only vitamin B12, or vitamin B12 with nutrients such as folic acid and other B vitamins, are also available. Check the Supplement Facts label to determine the amount of vitamin B12 provided.

Vitamin B12 is also available in sublingual forms (which are dissolved under the tongue). There is no evidence that sublingual forms are better absorbed than pills that are swallowed.

A prescription form of vitamin B12 can be administered as a shot. This is usually used to treat vitamin B12 deficiency. Vitamin B12 is also available as a prescription medication in nasal gel form (for use in the nose).
Am I getting enough vitamin B12?

Most people in the United States get enough vitamin B12 from the foods they eat. But some people have trouble absorbing vitamin B12 from food. As a result, vitamin B12 deficiency affects between 1.5% and 15% of the public. Your doctor can test your vitamin B12 level to see if you have a deficiency.

Certain groups may not get enough vitamin B12 or have trouble absorbing it:

    Many older adults, who do not have enough hydrochloric acid in their stomach to absorb the vitamin B12 naturally present in food. People over 50 should get most of their vitamin B12 from fortified foods or dietary supplements because, in most cases, their bodies can absorb vitamin B12 from these sources.
    People with pernicious anemia whose bodies do not make the intrinsic factor needed to absorb vitamin B12. Doctors usually treat pernicious anemia with vitamin B12 shots, although very high oral doses of vitamin B12 might also be effective.
    People who have had gastrointestinal surgery, such as weight loss surgery, or who have digestive disorders, such as celiac disease or Crohn's disease. These conditions can decrease the amount of vitamin B12 that the body can absorb.
    Some people who eat little or no animal foods such as vegetarians and vegans. Only animal foods have vitamin B12 naturally. When pregnant women and women who breastfeed their babies are strict vegetarians or vegans, their babies might also not get enough vitamin B12.

What happens if I don't get enough vitamin B12?

Vitamin B12 deficiency causes tiredness, weakness, constipation, loss of appetite, weight loss, and megaloblastic anemia. Nerve problems, such as numbness and tingling in the hands and feet, can also occur. Other symptoms of vitamin B12 deficiency include problems with balance, depression, confusion, dementia, poor memory, and soreness of the mouth or tongue. Vitamin B12 deficiency can damage the nervous system even in people who don't have anemia, so it is important to treat a deficiency as soon as possible.

In infants, signs of a vitamin B12 deficiency include failure to thrive, problems with movement, delays in reaching the typical developmental milestones, and megaloblastic anemia.

Large amounts of folic acid can hide a vitamin B12 deficiency by correcting megaloblastic anemia, a hallmark of vitamin B12 deficiency. But folic acid does not correct the progressive damage to the nervous system that vitamin B12 deficiency also causes. For this reason, healthy adults should not get more than 1,000 mcg of folic acid a day.
What are some effects of vitamin B12 on health?

Scientists are studying vitamin B12 to understand how it affects health. Here are several examples of what this research has shown:

Heart disease
Vitamin B12 supplements (along with folic acid and vitamin B6) do not reduce the risk of getting heart disease. Scientists had thought that these vitamins might be helpful because they reduce blood levels of homocysteine, a compound linked to an increased risk of having a heart attack or stroke.

Dementia
As they get older, some people develop dementia. These people often have high levels of homocysteine in the blood. Vitamin B12 (with folic acid and vitamin B6) can lower homocysteine levels, but scientists don't know yet whether these vitamins actually help prevent or treat dementia.

Energy and athletic performance
Advertisements often promote vitamin B12 supplements as a way to increase energy or endurance. Except in people with a vitamin B12 deficiency, no evidence shows that vitamin B12 supplements increase energy or improve athletic performance.
Can vitamin B12 be harmful?

Vitamin B12 has not been shown to cause any harm.
Are there any interactions with vitamin B12 that I should know about?

Yes. Vitamin B12 can interact or interfere with medicines that you take, and in some cases, medicines can lower vitamin B12 levels in the body. Here are several examples of medicines that can interfere with the body's absorption or use of vitamin B12:

    Chloramphenicol (Chloromycetin®), an antibiotic that is used to treat certain infections.
    Proton pump inhibitors, such as omeprazole (Prilosec®) and lansoprazole (Prevacid®), that are used to treat acid reflux and peptic ulcer disease.
    Histamine H2 receptor antagonists, such as cimetidine (Tagamet®), famotidine (Pepcid®), and ranitidine (Zantac®), that are used to treat peptic ulcer disease.
    Metformin, a drug used to treat diabetes.

Tell your doctor, pharmacist, and other health care providers about any dietary supplements and medicines you take. They can tell you if those dietary supplements might interact or interfere with your prescription or over-the-counter medicines or if the medicines might interfere with how your body absorbs, uses, or breaks down nutrients.
Vitamin B12 and healthful eating

People should get most of their nutrients from food, advises the federal government's Dietary Guidelines for Americans. Foods contain vitamins, minerals, dietary fiber and other substances that benefit health. Dietary supplements might help in some situations to increase the intake of a specific vitamin or mineral. For more information on building a healthy diet, refer to the Dietary Guidelines for Americansexternal link icon and the U.S. Department of Agriculture's food guidance system, ChooseMyPlateexternal link icon.

Vitamin C, also known as ascorbic acid, is a water-soluble nutrient found in some foods. In the body, it acts as an antioxidant, helping to protect cells from the damage caused by free radicals. Free radicals are compounds formed when our bodies convert the food we eat into energy. People are also exposed to free radicals in the environment from cigarette smoke, air pollution, and ultraviolet light from the sun.

The body also needs vitamin C to make collagen, a protein required to help wounds heal. In addition, vitamin C improves the absorption of iron from plant-based foods and helps the immune system work properly to protect the body from disease.
Table of Contents

    What is vitamin C and what does it do?
    How much vitamin C do I need?
    What foods provide vitamin C?
    What kinds of vitamin C dietary supplements are available?
    Am I getting enough vitamin C?
    What happens if I don't get enough vitamin C?
    What are some effects of vitamin C on health?
    Can vitamin C be harmful?
    Are there any interactions with vitamin C that I should know about?
    Vitamin C and healthful eating
    Where can I find out more about vitamin C?
    Disclaimer

How much vitamin C do I need?

The amount of vitamin C you need each day depends on your age. Average daily recommended amounts for different ages are listed below in milligrams (mg).
Life Stage     Recommended Amount
Birth to 6 months    40 mg
Infants 7–12 months    50 mg
Children 1–3 years    15 mg
Children 4–8 years    25 mg
Children 9–13 years    45 mg
Teens 14–18 years (boys)    75 mg
Teens 14–18 years (girls)    65 mg
Adults (men)    90 mg
Adults (women)    75 mg
Pregnant teens    80 mg
Pregnant women    85 mg
Breastfeeding teens    115 mg
Breastfeeding women    120 mg

If you smoke, add 35 mg to the above values to calculate your total daily recommended amount.
What foods provide vitamin C?

Fruits and vegetables are the best sources of vitamin C. You can get recommended amounts of vitamin C by eating a variety of foods including the following:

    Citrus fruits (such as oranges and grapefruit) and their juices, as well as red and green pepper and kiwifruit, which have a lot of vitamin C.
    Other fruits and vegetables—such as broccoli, strawberries, cantaloupe, baked potatoes, and tomatoes—which also have vitamin C.
    Some foods and beverages that are fortified with vitamin C. To find out if vitamin C has been added to a food product, check the product labels.

The vitamin C content of food may be reduced by prolonged storage and by cooking. Steaming or microwaving may lessen cooking losses. Fortunately, many of the best food sources of vitamin C, such as fruits and vegetables, are usually eaten raw.
What kinds of vitamin C dietary supplements are available?

Most multivitamins have vitamin C. Vitamin C is also available alone as a dietary supplement or in combination with other nutrients. The vitamin C in dietary supplements is usually in the form of ascorbic acid, but some supplements have other forms, such as sodium ascorbate, calcium ascorbate, other mineral ascorbates, and ascorbic acid with bioflavonoids. Research has not shown that any form of vitamin C is better than the other forms.
Am I getting enough vitamin C?

Most people in the United States get enough vitamin C from foods and beverages. However, certain groups of people are more likely than others to have trouble getting enough vitamin C:

    People who smoke and those who are exposed to secondhand smoke, in part because smoke increases the amount of vitamin C that the body needs to repair damage caused by free radicals. People who smoke need 35 mg more vitamin C per day than nonsmokers.
    Infants who are fed evaporated or boiled cow's milk, because cow's milk has very little vitamin C and heat can destroy vitamin C. Cow's milk is not recommended for infants under 1 year of age. Breast milk and infant formula have adequate amounts of vitamin C.
    People who eat a very limited variety of food.
    People with certain medical conditions such as severe malabsorption, some types of cancer, and kidney disease requiring hemodialysis.

What happens if I don't get enough vitamin C?

Vitamin C deficiency is rare in the United States and Canada. People who get little or no vitamin C (below about 10 mg per day) for many weeks can get scurvy. Scurvy causes fatigue, inflammation of the gums, small red or purple spots on the skin, joint pain, poor wound healing, and corkscrew hairs. Additional signs of scurvy include depression as well as swollen, bleeding gums and loosening or loss of teeth. People with scurvy can also develop anemia. Scurvy is fatal if it is not treated.
What are some effects of vitamin C on health?

Scientists are studying vitamin C to understand how it affects health. Here are several examples of what this research has shown.

Cancer prevention and treatment
People with high intakes of vitamin C from fruits and vegetables might have a lower risk of getting many types of cancer, such as lung, breast, and colon cancer. However, taking vitamin C supplements, with or without other antioxidants, doesn't seem to protect people from getting cancer.

It is not clear whether taking high doses of vitamin C is helpful as a treatment for cancer. Vitamin C's effects appear to depend on how it is administered to the patient. Oral doses of vitamin C can't raise blood levels of vitamin C nearly as high as intravenous doses given through injections. A few studies in animals and test tubes indicate that very high blood levels of vitamin C might shrink tumors. But more research is needed to determine whether high-dose intravenous vitamin C helps treat cancer in people.

Vitamin C dietary supplements and other antioxidants might interact with chemotherapy and radiation therapy for cancer. People being treated for cancer should talk with their oncologist before taking vitamin C or other antioxidant supplements, especially in high doses.

Cardiovascular disease
People who eat lots of fruits and vegetables seem to have a lower risk of cardiovascular disease. Researchers believe that the antioxidant content of these foods might be partly responsible for this association because oxidative damage is a major cause of cardiovascular disease. However, scientists aren't sure whether vitamin C itself, either from food or supplements, helps protect people from cardiovascular disease. It is also not clear whether vitamin C helps prevent cardiovascular disease from getting worse in people who already have it.

Age-related macular degeneration (AMD) and cataracts
AMD and cataracts are two of the leading causes of vision loss in older people. Researchers do not believe that vitamin C and other antioxidants affect the risk of getting AMD. However, research suggests that vitamin C combined with other nutrients might help keep early AMD from worsening into advanced AMD.

In a large study, older people with AMD who took a daily dietary supplement with 500 mg vitamin C, 80 mg zinc, 400 IU vitamin E, 15 mg beta-carotene, and 2 mg copper for about 6 years had a lower chance of developing advanced AMD. They also had less vision loss than those who did not take the dietary supplement.

More research is needed before doctors can recommend dietary supplements containing vitamin C for patients with AMD. However, people who have or are developing the disease might want to talk with their doctor about taking dietary supplements.

The relationship between vitamin C and cataract formation is unclear. Some studies show that people who get more vitamin C from foods have a lower risk of getting cataracts. But further research is needed to clarify this association and to determine whether vitamin C supplements affect the risk of getting cataracts.

The common cold
Although vitamin C has long been a popular remedy for the common cold, research shows that for most people, vitamin C supplements do not reduce the risk of getting the common cold. However, people who take vitamin C supplements regularly might have slightly shorter colds or somewhat milder symptoms when they do have a cold. Using vitamin C supplements after cold symptoms start does not appear to be helpful.
Can vitamin C be harmful?

Taking too much vitamin C can cause diarrhea, nausea, and stomach cramps. In people with a condition called hemochromatosis, which causes the body to store too much iron, high doses of vitamin C could worsen iron overload and damage body tissues.

The safe upper limits for vitamin C are listed below:
Life Stage     Upper Safe Limit
Birth to 12 months    Not established
Children 1–3 years    400 mg
Children 4–8 years    650 mg
Children 9–13 years    1,200 mg
Teens 14–18 years    1,800 mg
Adults    2,000 mg
Are there any interactions with vitamin C that I should know about?

Vitamin C dietary supplements can interact or interfere with medicines that you take. Here are several examples:

    Vitamin C dietary supplements might interact with cancer treatments, such as chemotherapy and radiation therapy. It is not clear whether vitamin C might have the unwanted effect of protecting tumor cells from cancer treatments or whether it might help protect normal tissues from getting damaged. If you are being treated for cancer, check with your health care provider before taking vitamin C or other antioxidant supplements, especially in high doses.
    In one study, vitamin C plus other antioxidants (such as vitamin E, selenium, and beta-carotene) reduced the heart-protective effects of two drugs taken in combination (a statin and niacin) to control blood-cholesterol levels. It is not known whether this interaction also occurs with other statins. Health care providers should monitor lipid levels in people taking both statins and antioxidant supplements.

Tell your doctor, pharmacist, and other health care providers about any dietary supplements and medicines you take. They can tell you if those dietary supplements might interact or interfere with your prescription or over-the-counter medicines or if the medicines might interfere with how your body absorbs, uses, or breaks down nutrients.
Vitamin C and healthful eating

People should get most of their nutrients from food, advises the federal government's Dietary Guidelines for Americans. Foods contain vitamins, minerals, dietary fiber and other substances that benefit health. Dietary supplements might help in some situations to increase the intake of a specific vitamin or mineral. For more information on building a healthy diet, refer to the Dietary Guidelines for Americansexternal link icon and the U.S. Department of Agriculture's food guidance system, ChooseMyPlateexternal link icon

A study will be published on March 21, 2009 in World Journal of Gastroenterology addresses the question.

A research group in King Saud University, Kingdom of Saudi Arabia investigated, for the first time, the role of carnitine, a naturally occurring compound that is synthesized mainly in the liver, during the development of hepatocarcinogenesis. Authors of the study reported that carnitine deficiency is a risk factor and should be viewed as a mechanism in hepatic carcinogenesis, and that long-term L-carnitine supplementation prevents the development of liver cancer. Therefore, carnitine supplementation alone or in combination with other natural chemopreventive compounds could be used to prevent, slow or reverse the occurrence of liver cancer.

Chemoprevention is defined as the use of naturally occurring and/or synthetic compounds in cancer therapy in which the occurrence of cancer can be entirely prevented, slowed or reversed. L-carnitine is a naturally occurring compound which is primarily located in mitochondria and possesses potential protective effects against many mitochondrial toxic agents. It is derived from two sources; endogenous synthesis, in the liver and kidney, and from exogenous dietary sources such as red meat and dairy products. L-carnitine is an essential cofactor for the translocation of long chain fatty acids from the cytoplasmic compartment into mitochondria, where beta-oxidation enzymes are located for ATP production. Despite the liver being the main organ responsible for endogenous synthesis of L-carnitine, we were unable to find any studies investigating the role of long-term endogenous carnitine depletion and/or carnitine deficiency during induction of hepatic carcinogenesis.

The research team by Professor Sayed-Ahmed from College of Pharmacy, King Saud University used an experimental model of hepatocarcinogenesis under conditions of carnitine depletion and carnitine supplementation.


In the carnitine-depleted rat model, there were a progressive increase in the activities of liver enzymes as well as massive degenerative changes and evidence of pre-neoplastic lesions in liver tissues including clusters of hepatocytes with atypia and an increased proliferative rate, diffuse bridging fibrosis and nodule formation, bile ducts with marked reactive atypia showing nuclear enlargement, high nuclear/cytoplasmic ratio and prominent nucleoli. Interestingly, L-carnitine supplementation resulted in a complete reversal of the increase in liver enzymes compared to normal values, as well as normal liver histology with unremarkable central vein and no evidence of pre-neoplastic lesions in liver tissues.

Due to the fact that liver cancer is one of the major health problems in the world and a large sector of patients seek medical attention at a relatively late stage which increases the cost of treatment, King Saud University granted Prof. Sayed-Ahmed and his colleagues a research project with the following specific aims: (1) to understand the possible molecular mechanisms whereby carnitine deficiency provokes hepatic carcinogenesis. (2) to understand the relationship between hepatic cancer and its resistance to cancer chemotherapy, and (3) to gain knowledge on the possible mechanisms by which carnitine supplementation alone or in combination with other natural chemopreventive compounds could be used to prevent, slow or reverse the occurrence of liver cancer.
Source:

http://www.wjgnet.com/

Chromium is a mineral that humans require in trace amounts, although its mechanisms of action in the body and the amounts needed for optimal health are not well defined. It is found primarily in two forms: 1) trivalent (chromium 3+), which is biologically active and found in food, and 2) hexavalent (chromium 6+), a toxic form that results from industrial pollution. This fact sheet focuses exclusively on trivalent (3+) chromium.

Chromium is known to enhance the action of insulin [1-3], a hormone critical to the metabolism and storage of carbohydrate, fat, and protein in the body [4]. In 1957, a compound in brewers' yeast was found to prevent an age-related decline in the ability of rats to maintain normal levels of sugar (glucose) in their blood [3]. Chromium was identified as the active ingredient in this so-called "glucose tolerance factor" in 1959 [5].

Chromium also appears to be directly involved in carbohydrate, fat, and protein metabolism [1-2,6-11], but more research is needed to determine the full range of its roles in the body. The challenges to meeting this goal include:

    Defining the types of individuals who respond to chromium supplementation;
    Evaluating the chromium content of foods and its bioavailability;
    Determining if a clinically relevant chromium-deficiency state exists in humans due to inadequate dietary intakes; and
    Developing valid and reliable measures of chromium status [9].

Table of Contents

    Chromium: What is it?
    What foods provide chromium?
    What are recommended intakes of chromium?
    What affects chromium levels in the body?
    When can a chromium deficiency occur?
    Who may need extra chromium?
    What are some current issues and controversies about chromium?
    What are the health risks of too much chromium?
    Chromium and medication interactions
    Supplemental sources of chromium
    Chromium and Healthful Diets
    References
    Disclaimer

What foods provide chromium?

Chromium is widely distributed in the food supply, but most foods provide only small amounts (less than 2 micrograms [mcg] per serving). Meat and whole-grain products, as well as some fruits, vegetables, and spices are relatively good sources [12]. In contrast, foods high in simple sugars (like sucrose and fructose) are low in chromium [13].

Dietary intakes of chromium cannot be reliably determined because the content of the mineral in foods is substantially affected by agricultural and manufacturing processes and perhaps by contamination with chromium when the foods are analyzed [10,12,14]. Therefore, Table 1, and food-composition databases generally, provide approximate values of chromium in foods that should only serve as a guide.
Table 1: Selected food sources of chromium [12,15-16] Food     Chromium (mcg)
Broccoli, ½ cup     11
Grape juice, 1 cup     8
English muffin, whole wheat, 1     4
Potatoes, mashed, 1 cup     3
Garlic, dried, 1 teaspoon     3
Basil, dried, 1 tablespoon     2
Beef cubes, 3 ounces     2
Orange juice, 1 cup     2
Turkey breast, 3 ounces     2
Whole wheat bread, 2 slices     2
Red wine, 5 ounces     1–13
Apple, unpeeled, 1 medium     1
Banana, 1 medium     1
Green beans, ½ cup     1
What are recommended intakes of chromium?

Recommended chromium intakes are provided in the Dietary Reference Intakes (DRIs) developed by the Institute of Medicine of the National Academy of Sciences [14]. Dietary Reference Intakes is the general term for a set of reference values to plan and assess the nutrient intakes of healthy people. These values include the Recommended Dietary Allowance (RDA) and the Adequate Intake (AI). The RDA is the average daily intake that meets a nutrient requirement of nearly all (97 to 98%) healthy individuals [14]. An AI is established when there is insufficient research to establish an RDA; it is generally set at a level that healthy people typically consume.

In 1989, the National Academy of Sciences established an "estimated safe and adequate daily dietary intake" range for chromium. For adults and adolescents that range was 50 to 200 mcg [17]. In 2001, DRIs for chromium were established. The research base was insufficient to establish RDAs, so AIs were developed based on average intakes of chromium from food as found in several studies [14]. Chromium AIs are provided in Table 2.
Table 2: Adequate Intakes (AIs) for chromium [14] Age     Infants and children
(mcg/day)     Males
(mcg/day)     Females
(mcg/day)     Pregnancy
(mcg/day)     Lactation
(mcg/day)
0 to 6 months    0.2                   
7 to 12 months    5.5                   
1 to 3 years    11                   
4 to 8 years    15                   
9 to 13 years         25    21         
14 to 18 years         35    24    29    44
19 to 50 years         35    25    30    45
>50 years         30    20         

mcg = micrograms

Adult women in the United States consume about 23 to 29 mcg of chromium per day from food, which meets their AIs unless they're pregnant or lactating. In contrast, adult men average 39 to 54 mcg per day, which exceeds their AIs [14].

The average amount of chromium in the breast milk of healthy, well-nourished mothers is 0.24 mcg per quart, so infants exclusively fed breast milk obtain about 0.2 mcg (based on an estimated consumption of 0.82 quarts per day) [14]. Infant formula provides about 0.5 mcg of chromium per quart [18]. No studies have compared how well infants absorb and utilize chromium from human milk and formula [10,14].
What affects chromium levels in the body?

Absorption of chromium from the intestinal tract is low, ranging from less than 0.4% to 2.5% of the amount consumed [19-25], and the remainder is excreted in the feces [1,23]. Enhancing the mineral's absorption are vitamin C (found in fruits and vegetables and their juices) and the B vitamin niacin (found in meats, poultry, fish, and grain products) [26]. Absorbed chromium is stored in the liver, spleen, soft tissue, and bone [27].

The body's chromium content may be reduced under several conditions. Diets high in simple sugars (comprising more than 35% of calories) can increase chromium excretion in the urine [13]. Infection, acute exercise, pregnancy and lactation, and stressful states (such as physical trauma) increase chromium losses and can lead to deficiency, especially if chromium intakes are already low [28-29].
When can a chromium deficiency occur?

In the 1960s, chromium was found to correct glucose intolerance and insulin resistance in deficient animals, two indicators that the body is failing to properly control blood-sugar levels and which are precursors of type 2 diabetes [1]. However, reports of actual chromium deficiency in humans are rare. Three hospitalized patients who were fed intravenously showed signs of diabetes (including weight loss, neuropathy, and impaired glucose tolerance) until chromium was added to their feeding solution. The chromium, added at doses of 150 to 250 mcg/day for up to two weeks, corrected their diabetes symptoms [7,30-31]. Chromium is now routinely added to intravenous solutions.
Who may need extra chromium?

There are reports of significant age-related decreases in the chromium concentrations of hair, sweat and blood [32], which might suggest that older people are more vulnerable to chromium depletion than younger adults [14]. One cannot be sure, however, as chromium status is difficult to determine [33]. That's because blood, urine, and hair levels do not necessarily reflect body stores [9,14]. Furthermore, no chromium-specific enzyme or other biochemical marker has been found to reliably assess a person's chromium status [9,34].

There is considerable interest in the possibility that supplemental chromium may help to treat impaired glucose tolerance and type 2 diabetes, but the research to date is inconclusive. No large, randomized, controlled clinical trials testing this hypothesis have been reported in the United States [14]. Nevertheless, this is an active area of research.
What are some current issues and controversies about chromium?

Chromium has long been of interest for its possible connection to various health conditions. Among the most active areas of chromium research are its use in supplement form to treat diabetes, lower blood lipid levels, promote weight loss, and improve body composition.

Type 2 diabetes and glucose intolerance
In type 2 diabetes, the pancreas is usually producing enough insulin but, for unknown reasons, the body cannot use the insulin effectively. The disease typically occurs, in part, because the cells comprising muscle and other tissues become resistant to insulin's action, especially among the obese. Insulin permits the entry of glucose into most cells, where this sugar is used for energy, stored in the liver and muscles (as glycogen), and converted to fat when present in excess. Insulin resistance leads to higher than normal levels of glucose in the blood (hyperglycemia).

Chromium deficiency impairs the body's ability to use glucose to meet its energy needs and raises insulin requirements. It has therefore been suggested that chromium supplements might help to control type 2 diabetes or the glucose and insulin responses in persons at high risk of developing the disease. A review of randomized controlled clinical trials evaluated this hypothesis [35]. This meta-analysis assessed the effects of chromium supplements on three markers of diabetes in the blood: glucose, insulin, and glycated hemoglobin (which provides a measure of long-term glucose levels; also known as hemoglobin A1C). It summarized data from 15 trials on 618 participants, of which 425 were in good health or had impaired glucose tolerance and 193 had type 2 diabetes. Chromium supplementation had no effect on glucose or insulin concentrations in subjects without diabetes nor did it reduce these levels in subjects with diabetes, except in one study. However, that study, conducted in China (in which 155 subjects with diabetes were given either 200 or 1,000 mcg/day of chromium or a placebo) might simply show the benefits of supplementation in a chromium-deficient population.

Overall, the value of chromium supplements for diabetes is inconclusive and controversial [36]. Randomized controlled clinical trials in well-defined, at-risk populations where dietary intakes are known are necessary to determine the effects of chromium on markers of diabetes [35]. The American Diabetes Association states that there is insufficient evidence to support the routine use of chromium to improve glycemic control in people with diabetes [37]. It further notes that there is no clear scientific evidence that vitamin and mineral supplementation benefits people with diabetes who do not have underlying nutritional deficiencies.

Lipid metabolism
The effects of chromium supplementation on blood lipid levels in humans are also inconclusive [1,8,38]. In some studies, 150 to 1,000 mcg/day has decreased total and low-density-lipoprotein (LDL or "bad") cholesterol and triglyceride levels and increased concentrations of apolipoprotein A (a component of high-density-lipoprotein cholesterol known as HDL or "good" cholesterol) in subjects with atherosclerosis or elevated cholesterol or among those taking a beta-blocker drug [39-41]. These findings are consistent with the results of earlier studies [42-45].

However, chromium supplements have shown no favorable effects on blood lipids in other studies [46-51]. The mixed research findings may be due to difficulties in determining the chromium status of subjects at the start of the trials and the researchers' failure to control for dietary factors that influence blood lipid levels [9-10].

Body weight and composition
Chromium supplements are sometimes claimed to reduce body fat and increase lean (muscle) mass. Yet a recent review of 24 studies that examined the effects of 200 to 1,000 mcg/day of chromium (in the form of chromium picolinate) on body mass or composition found no significant benefits [11]. Another recent review of randomized, controlled clinical trials did find supplements of chromium picolinate to help with weight loss when compared wtth placebos, but the differences were small and of debatable clinical relevance [52]. In several studies, chromium's effects on body weight and composition may be called into question because the researchers failed to adequately control for the participants' food intakes. Furthermore, most studies included only a small number of subjects and were of short duration [36].
What are the health risks of too much chromium?

Few serious adverse effects have been linked to high intakes of chromium, so the Institute of Medicine has not established a Tolerable Upper Intake Level (UL) for this mineral [10,14]. A UL is the maximum daily intake of a nutrient that is unlikely to cause adverse health effects. It is one of the values (together with the RDA and AI) that comprise the Dietary Reference Intakes (DRIs) for each nutrient.
Chromium and medication interactions

Certain medications may interact with chromium, especially when taken on a regular basis (see Table 3). Before taking dietary supplements, check with your doctor or other qualified healthcare provider, especially if you take prescription or over-the-counter medications.
Table 3: Interactions between chromium and medications [14,53-55] Medications     Nature of interaction

    Antacids
    Corticosteroids
    H2 blockers (such as cimetidine, famotidine, nizatidine, and rantidine)
    Proton-pump inhibitors (such as omeprazole, lansoprazole, rabeprazole, pantoprazole, and esomeprazole)

    These medications alter stomach acidity and may impair chromium absorption or enhance excretion

    Beta-blockers (such as atenolol or propanolol)
    Corticosteroids
    Insulin
    Nicotinic acid
    Nonsteroidal anti-inflammatory drugs (NSAIDS)
    Prostaglandin inhibitors (such as ibuprofen, indomethacin, naproxen, piroxicam, and aspirin)

    These medications may have their effects enhanced if taken together with chromium or they may increase chromium absorption
Supplemental sources of chromium

Chromium is a widely used supplement. Estimated sales to consumers were $85 million in 2002, representing 5.6% of the total mineral-supplement market [56]. Chromium is sold as a single-ingredient supplement as well as in combination formulas, particularly those marketed for weight loss and performance enhancement. Supplement doses typically range from 50 to 200 mcg.

The safety and efficacy of chromium supplements need more investigation. Please consult with a doctor or other trained healthcare professional before taking any dietary supplements.

Chromium supplements are available as chromium chloride, chromium nicotinate, chromium picolinate, high-chromium yeast, and chromium citrate. Chromium chloride in particular appears to have poor bioavailability [36]. However, given the limited data on chromium absorption in humans, it is not clear which forms are best to take.
Chromium and Healthful Diets

The federal government's 2010 Dietary Guidelines for Americans notes that "nutrients should come primarily from foods. Foods in nutrient-dense, mostly intact forms contain not only the essential vitamins and minerals that are often contained in nutrient supplements, but also dietary fiber and other naturally occurring substances that may have positive health effects. ...Dietary supplements...may be advantageous in specific situations to increase intake of a specific vitamin or mineral."

For more information about building a healthful diet, refer to the Dietary Guidelines for Americansexternal link icon and the U.S. Department of Agriculture's food guidance system, MyPlateexternal link icon.

The Dietary Guidelines for Americans describes a healthy diet as one that:

    Emphasizes a variety of fruits, vegetables, whole grains, and fat-free or low-fat milk and milk products.

        Whole grain products and certain fruits and vegetables like broccoli, potatoes, grape juice, and oranges are sources of chromium. Ready-to-eat bran cereals can also be a relatively good source of chromium.

    Includes lean meats, poultry, fish, beans, eggs, and nuts.

        Lean beef, oysters, eggs, and turkey are sources of chromium.

    Is low in saturated fats, trans fats, cholesterol, salt (sodium), and added sugars.
    Stays within your daily calorie needs.

References

    Mertz W. Chromium occurrence and function in biological systems. Physiol Rev 1969;49:163-239.
    Mertz W. Chromium in human nutrition: a review. J Nutr 1993;123:626-33.
    Mertz W. Interaction of chromium with insulin: a progress report. Nutr Rev 1998;56:174-7.
    Porte Jr. D, Sherwin RS, Baron A (editors). Ellengerg & Rifkin's Diabetes Mellitus, 6th Edition. McGraw-Hill, New York, 2003.
    Schwarz K, Mertz W. Chromium(III) and the glucose tolerance factor. Arch Biochem Biophys 1959;85:292-5.

More than 371 million people worldwide suffer from diabetes, of whom 90% are affected by lifestyle-related diabetes mellitus type 2 (type 2 diabetes).

In new experiments, researchers from the University of Copenhagen working in collaboration with a research group at the University of Cincinnati, USA, have demonstrated that the amino acid arginine improves glucose metabolism significantly in both lean (insulin-sensitive) and obese (insulin-resistant) mice.

"In fact, the amino acid is just as effective as several well-established drugs for type 2 diabetics," says postdoc Christoffer Clemmensen. He has conducted the new experiments based at Faculty of Health and Medical Sciences, University of Copenhagen. He is currently conducting research at the Institute for Diabetes and Obesity at Helmholtz Zentrum M-nchen, the German Research Centre for Environmental Health in Munich.

To test the effect of the amino acid arginine, researchers subjected lean and obese animal models to a so-called glucose tolerance test, which measures the body's ability to remove glucose from the blood over time.

"We have demonstrated that both lean and fat laboratory mice benefit considerably from arginine supplements. In fact, we improved glucose metabolism by as much as 40% in both groups. We can also see that arginine increases the body's production of glucagon-like peptide-1 (GLP-1), an intestinal hormone which plays an important role in regulating appetite and glucose metabolism, and which is therefore used in numerous drugs for treating type 2 diabetes," says Christoffer Clemmensen, and continues:

"You cannot, of course, cure diabetes by eating unlimited quantities of arginine-rich almonds and hazelnuts. However, our findings indicate that diet-based interventions with arginine-containing foods can have a positive effect on how the body processes the food we eat."


The research findings were recently published in the American scientific journal Endocrinology under the heading Oral l-arginine Stimulates GLP-1 Secretion to Improve Glucose Tolerance in Male Mice.

Hormone plays key role

Researchers have known for many years that the amino acid arginine is important for the body's ability to secrete insulin. However, the latest findings show that it is an indirect process. The process is actually controlled by arginine's ability to secrete the intestinal hormone GLP-1, which subsequently affects insulin secretion.

"Mice without GLP-1 receptors are not affected to the same extent by arginine. There is no perceptible improvement in glucose metabolism or insulin secretion, confirming our hypothesis of a close biological connection between GLP-1 and arginine," says Christoffer Clemmensen, who conducted the biological experiments in the USA using a special animal model where the receptor for GLP-1 is genetically inactivated.

The new findings provide optimism for better and more targeted drugs for treating type 2 diabetes; the outlook is long-term, but promising.

"This exciting result has raised several new questions which we want to investigate. Can other amino acids do what arginine does? Which intestinal mechanisms 'measure' arginine and lead to the release of GLP-1? Finally, there is the more long-term perspective - the question of whether the findings can be transferred from mice to humans and be used to design drugs that will benefit diabetes patients," says Professor Hans Br-uner-Osborne, who is continuing work on the project in the research group at the Department of Drug Design and Pharmacology at the University of Copenhagen.
Source:

University of Copenhagen

What is vitamin D and what does it do?

Vitamin D is a nutrient found in some foods that is needed for health and to maintain strong bones. It does so by helping the body absorb calcium (one of bone's main building blocks) from food and supplements. People who get too little vitamin D may develop soft, thin, and brittle bones, a condition known as rickets in children and osteomalacia in adults.

Vitamin D is important to the body in many other ways as well. Muscles need it to move, for example, nerves need it to carry messages between the brain and every body part, and the immune system needs vitamin D to fight off invading bacteria and viruses. Together with calcium, vitamin D also helps protect older adults from osteoporosis. Vitamin D is found in cells throughout the body.
Table of Contents

    What is vitamin D and what does it do?
    How much vitamin D do I need?
    What foods provide vitamin D?
    Can I get vitamin D from the sun?
    What kinds of vitamin D dietary supplements are available?
    Am I getting enough vitamin D?
    What happens if I don't get enough vitamin D?
    What are some effects of vitamin D on health?
    Can vitamin D be harmful?
    Are there any interactions with vitamin D that I should know about?
    Vitamin D and healthful eating
    Where can I find out more about vitamin D?
    Disclaimer

How much vitamin D do I need?

The amount of vitamin D you need each day depends on your age. Average daily recommended amounts from the Food and Nutrition Board (a national group of experts) for different ages are listed below in International Units (IU):
Life Stage     Recommended Amount
Birth to 12 months    400 IU
Children 1–13 years    600 IU
Teens 14–18 years    600 IU
Adults 19–70 years    600 IU
Adults 71 years and older    800 IU
Pregnant and breastfeeding women    600 IU
What foods provide vitamin D?

Very few foods naturally have vitamin D. Fortified foods provide most of the vitamin D in American diets.

    Fatty fish such as salmon, tuna, and mackerel are among the best sources.
    Beef liver, cheese, and egg yolks provide small amounts.
    Mushrooms provide some vitamin D. In some mushrooms that are newly available in stores, the vitamin D content is being boosted by exposing these mushrooms to ultraviolet light.
    Almost all of the U.S. milk supply is fortified with 400 IU of vitamin D per quart. But foods made from milk, like cheese and ice cream, are usually not fortified.
    Vitamin D is added to many breakfast cereals and to some brands of orange juice, yogurt, margarine, and soy beverages; check the labels.

Can I get vitamin D from the sun?

The body makes vitamin D when skin is directly exposed to the sun, and most people meet at least some of their vitamin D needs this way. Skin exposed to sunshine indoors through a window will not produce vitamin D. Cloudy days, shade, and having dark-colored skin also cut down on the amount of vitamin D the skin makes.

However, despite the importance of the sun to vitamin D synthesis, it is prudent to limit exposure of skin to sunlight in order to lower the risk for skin cancer. When out in the sun for more than a few minutes, wear protective clothing and apply sunscreen with an SPF (sun protection factor) of 8 or more. Tanning beds also cause the skin to make vitamin D, but pose similar risks for skin cancer.

People who avoid the sun or who cover their bodies with sunscreen or clothing should include good sources of vitamin D in their diets or take a supplement. Recommended intakes of vitamin D are set on the assumption of little sun exposure.
What kinds of vitamin D dietary supplements are available?

Vitamin D is found in supplements (and fortified foods) in two different forms: D2 (ergocalciferol) and D3 (cholecalciferol). Both increase vitamin D in the blood.
Am I getting enough vitamin D?

Because vitamin D can come from sun, food, and supplements, the best measure of one's vitamin D status is blood levels of a form known as 25-hydroxyvitamin D. Levels are described in either nanomoles per liter (nmol/L) or nanograms per milliliter (ng/mL), where 1 nmol/L = 0.4 ng/mL.

In general, levels below 30 nmol/L (12 ng/mL) are too low for bone or overall health, and levels above 125 nmol/L (50 ng/mL) are probably too high. Levels of 50 nmol/L or above (20 ng/mL or above) are sufficient for most people.

By these measures, some Americans are vitamin D deficient and almost no one has levels that are too high. In general, young people have higher blood levels of 25-hydroxyvitamin D than older people and males have higher levels than females. By race, non-Hispanic blacks tend to have the lowest levels and non-Hispanic whites the highest. The majority of Americans have blood levels lower than 75 nmol/L (30 ng/mL).

Certain other groups may not get enough vitamin D:

    Breastfed infants, since human milk is a poor source of the nutrient. Breastfed infants should be given a supplement of 400 IU of vitamin D each day.
    Older adults, since their skin doesn't make vitamin D when exposed to sunlight as efficiently as when they were young, and their kidneys are less able to convert vitamin D to its active form.
    People with dark skin, because their skin has less ability to produce vitamin D from the sun.
    People with disorders such as Crohn's disease or celiac disease who don't handle fat properly, because vitamin D needs fat to be absorbed.
    Obese people, because their body fat binds to some vitamin D and prevents it from getting into the blood.

What happens if I don't get enough vitamin D?

People can become deficient in vitamin D because they don't consume enough or absorb enough from food, their exposure to sunlight is limited, or their kidneys cannot convert vitamin D to its active form in the body. In children, vitamin D deficiency causes rickets, where the bones become soft and bend. It's a rare disease but still occurs, especially among African American infants and children. In adults, vitamin D deficiency leads to osteomalacia, causing bone pain and muscle weakness.
What are some effects of vitamin D on health?

Vitamin D is being studied for its possible connections to several diseases and medical problems, including diabetes, hypertension, and autoimmune conditions such as multiple sclerosis. Two of them discussed below are bone disorders and some types of cancer.

Bone disorders
As they get older, millions of people (mostly women, but men too) develop, or are at risk of, osteoporosis, where bones become fragile and may fracture if one falls. It is one consequence of not getting enough calcium and vitamin D over the long term. Supplements of both vitamin D3 (at 700–800 IU/day) and calcium (500–1,200 mg/day) have been shown to reduce the risk of bone loss and fractures in elderly people aged 62–85 years. Men and women should talk with their health care providers about their needs for vitamin D (and calcium) as part of an overall plan to prevent or treat osteoporosis.

Cancer
Some studies suggest that vitamin D may protect against colon cancer and perhaps even cancers of the prostate and breast. But higher levels of vitamin D in the blood have also been linked to higher rates of pancreatic cancer. At this time, it's too early to say whether low vitamin D status increases cancer risk and whether higher levels protect or even increase risk in some people.
Can vitamin D be harmful?

Yes, when amounts in the blood become too high. Signs of toxicity include nausea, vomiting, poor appetite, constipation, weakness, and weight loss. And by raising blood levels of calcium, too much vitamin D can cause confusion, disorientation, and problems with heart rhythm. Excess vitamin D can also damage the kidneys.

The safe upper limit for vitamin D is 1,000 to 1,500 IU/day for infants, 2,500 to 3,000 IU/day for children 1-8 years, and 4,000 IU/day for children 9 years and older, adults, and pregnant and lactating teens and women. Vitamin D toxicity almost always occurs from overuse of supplements. Excessive sun exposure doesn't cause vitamin D poisoning because the body limits the amount of this vitamin it produces.
Are there any interactions with vitamin D that I should know about?

Like most dietary supplements, vitamin D may interact or interfere with other medicines or supplements you might be taking. Here are several examples:

    Prednisone and other corticosteroid medicines to reduce inflammation impair how the body handles vitamin D, which leads to lower calcium absorption and loss of bone over time.
    Both the weight-loss drug orlistat (brand names Xenical® and Alli®) and the cholesterol-lowering drug cholestyramine (brand names Questran®, LoCholest®, and Prevalite®) can reduce the absorption of vitamin D and other fat-soluble vitamins (A, E, and K).
    Both phenobarbital and phenytoin (brand name Dilantin®), used to prevent and control epileptic seizures, increase the breakdown of vitamin D and reduce calcium absorption.

Tell your doctor, pharmacist, and other health care providers about any dietary supplements and medicines you take. They can tell you if those dietary supplements might interact or interfere with your prescription or over-the-counter medicines, or if the medicines might interfere with how your body absorbs, uses, or breaks down nutrients.
Vitamin D and healthful eating

People should get most of their nutrients from food, advises the federal government's Dietary Guidelines for Americans. Foods contain vitamins, minerals, dietary fiber and other substances that benefit health. Dietary supplements might help in some situations to increase the intake of a specific vitamin or mineral. For more information on building a healthy diet, refer to the Dietary Guidelines for Americansexternal link icon and the U.S. Department of Agriculture's food guidance system, ChooseMyPlateexternal link icon.

L-carnitine significantly improves cardiac health in patients after a heart attack, say a multicenter team of investigators in a study published today in Mayo Clinic Proceedings. Their findings, based on analysis of key controlled trials, associate L-carnitine with significant reduction in death from all causes and a highly significant reduction in ventricular arrhythmias and anginal attacks following a heart attack, compared with placebo or control.

Heart disease is the leading cause of death in the United States. Although many of the therapies developed in recent decades have markedly improved life expectancy, adverse cardiovascular events such as ventricular arrhythmias and angina attacks still occur frequently after an acute myocardial infarction (heart attack).

It is known that during ischemic events L-carnitine levels are depleted. Investigators sought to determine the effects of targeting cardiac metabolic pathways using L-carnitine to improve free fatty acid levels and glucose oxidation in these patients. By performing a systematic review and meta-analysis of the available studies published over several decades, they looked at the role of L-carnitine compared with placebo or control in patients experiencing an acute myocardial infarction.

L-carnitine is a trimethylamine which occurs in high amounts in red meat and is found in certain other foods, and is also widely available as an over-the-counter nutritional supplement which is claimed to improve energy, weight loss, and athletic performance. Its potential role in treating heart disease was first reported in the late 1970s.

A comprehensive literature search yielded 153 studies, 13, published from 1989-2007, were deemed eligible. All the trials were comparison trials of L-carnitine compared with placebo or control in the setting of acute myocardial infarction.

This systematic review of the 13 controlled trials in 3,629 patients, involving 250 deaths, 220 cases of new heart failure, and 38 recurrent heart attacks, found that L-carnitine was associated with:

    

There were numerically fewer myocardial reinfarctions and heart failure cases associated with L-carnitine, but this did not reach statistical significance.

First author James J. DiNicolantonio, PharmD, Wegmans Pharmacy, Ithaca, NY, observes, "Although therapies for acute coronary syndrome (ACS), including percutaneous coronary intervention, dual antiplatelet therapy, b-blockers (BBs), statins, angiotensin-converting enzyme inhibitors (ACEIs), omega-3 fatty acids, and cardiac rehabilitation, have markedly improved clinical outcomes, adverse cardiovascular (CV) events still occur too frequently after ACS. One promising therapy for improving cardiac health involves using L-carnitine to improve free fatty acid levels and glucose oxidation."


"The potential mechanisms responsible for the observed beneficial impact of L-carnitine in acute myocardial infarction are likely multifactorial and may, in part, be conferred through the ability of L-carnitine to improve mitochondrial energy metabolism in the heart by facilitating the transport of long-chain fatty acids from the cytosol to the mitochondrial matrix, where b-oxidation occurs, removing toxic fatty acid intermediates, reducing ischemia induced by long-chain fatty acid concentrations, and replenishing depleted carnitine concentrations seen in ischemic, infarcted, and failing myocardium," says DiNicolantonio.

L-carnitine is proven to be safe and is readily available over the counter. The investigators agree that the overall results of this meta-analysis support the potential use of L-carnitine in acute myocardial infarction and possibly in secondary coronary prevention and treatment, including angina. They advocate for a larger randomized, multicenter trial to be performed to confirm these results in the modern era of routine revascularization and other intensive medical therapies following acute myocardial infarction. But, says DiNicolantonio, "L-carnitine therapy can already be considered in selected patients with high-risk or persistent angina after acute myocardial infarction who cannot tolerate treatment with ACE inhibitors or beta blockers, considering its low cost and excellent safety profile."

These findings may seem to contradict those reported in a study published earlier this month in Nature Medicine by Robert A. Koeth and others (Koeth, R. A. et al. Nature Med. http://dx.doi.org/10.1038/nm.3145), which demonstrated that metabolism by intestinal microbiota of dietary L-carnitine produced trimethylamine N-oxide (TMAO) and accelerated atherosclerosis in mice. They also noted that omnivorous human subjects produced more TMAO than did vegans or vegetarians following ingestion of L-carnitine, and suggested a possible direct link between L-carnitine, gut bacteria, TMAO, and atherosclerosis and risk of ischemic heart disease.

"The Nature Medicine paper is of interest," agrees senior investigator Carl J. Lavie, M.D.,FACC,FACP,FCCP, Medical Director of the Cardiac Rehabilitation and Prevention Center at the John Ochsner Heart and Vascular Institute at the University of Queensland School of Medicine in New Orleans, "but the main study reported there was in animals, and unlike our study, lacks hard outcomes." He also notes that "there are various forms of 'carnitine' and our relatively large meta-analysis specifically tested L-carnitine on hard outcomes in humans who had already experienced acute myocardial infarction."
Source:

Elsevier Health Sciences

کارنیتین Carnitine یا ال-کارنیتین (L-carnitine) از اسیدهای آمینه لیزین و متیونین ساخته شده و موجب آزاد سازی انرژی از یاخته‌های چربی می‌شود. این ماده موجب انتقال اسیدهای چرب به داخل میتوکندری می‌شود. به گزارش خبرنگار سایت پزشکان بدون مرز، کارنیتین در بافت عضلات و کبد ساخته می‌شود و در برخی مواد غذایی مانند گوشت، گوشت طیور، ماهی، و برخی از فراورده‌های لبنی وجود دارد.کارنیتین نوعی مکمل غذایی است. وظیفه اصلی کارنیتین در بدن کمک به سوخت و ساز وتبدیل غذا به انرژی می باشد. کارنیتین این عمل را از طریق انتقال اسیدهای چرب بلند زنجیره به داخل میتوکندری ها جهت بتااکسیداسیون آن‌ها انجام می دهد. از طرف دیگر مصرف چربی‌ها به عنوان منبع انرژی موجب صرفه جویی در مصرف گلیگوژن عضلات گردیده و با حفظ ذخایر گلیکوژن به تأخیر در بروز خستگی ورزش کار می انجامد. میتوکندری را می‌توان موتورخانه یاخته‌های بدن دانست. در واقع انرژی مورد نیاز بدن در این بخش از یاخته‌ها تولید می‌شود. کارنیتین یک ترکیب چهار تایی آمونیوم است که از اسیدهای آمینه لیزین و متیونین ساخته شده است. در سلولهای زنده نقش آن فرستادن اسیدهای چرب از سیتوسل به میتوکندری در طی فرایند تفکیک چربی (یا چربی های مورد نیاز) برای سوختن است که انرژی آزاد کنند. در بدن، در کبد و کلیه ها تولید شده و در عضلات اسکلتی ، قلب ، مغز و اسپرم ذخیره شده است. معمولا ، بدن همه کارنیتینی که به آن نیاز دارد را می تواند بسازد. با این حال ، برخی از افراد ممکن است دچار کمبود کارنیتین شوند زیرا بدن آنها نمی تواند به اندازه کافی کارنیتین بسازد و یا آن را به بافت ها برای استفاده انتقال بدهد. برخی از شرایط دیگر مانند آنژین ، همچنین مصرف برخی از داروها می تواند باعث کمبود کارنیتین در بدن شود. برخی از شواهد نشان می‌دهد که میزان نیاز به ال-کارنیتین در دوران کودکی و همچنین در زمان‌های خاصی مانند بارداری و شیردهی که میزان نیاز بدن به انرژی افزایش می‌یابد کمی بالا می‌رود که این افزایش نیاز موجب به افزایش تولید این ماده غذایی از سوی بدن می‌شود. همچنین به‌نظر می‌رسد که وجود ال-کارنیتین برای بهبود کارکرد قلب نیاز است. برای نمونه یک پژوهش نشان داده است میزان کارکرد نابهنجار و تپش غیرعادی قلب بعد از ۴۵ هفته مصرف ۴ گرم ال-کارنیتین در روز در بیماران دیابتی که علاوه بر فشار خون بالا از ناراحتی‌های قلبی و رگی رنج می‌بردند به میزان زیادی کاهش یافته و بهبود پیدا نموده است. همچنین پژوهش دیگر نشان داده است که مصرف روزانه ال-کارنیتین در ورزشکاران می‌تواند حتی تا ۲۵٪ میزان توانایی و ظرفیت فعالیت بدنی را بالا ببرد. افرادی که از مکمل‌های ال-کارنیتین استفاده می‌نمایند بعد از انجام فعالیت‌های بدنی به میزان کمتری دچار خستگی و کوفتگی می‌شوند. این بررسی همچنان نشان داد که مصرف ال-کارنیتین دو ساعت پیش و پس از دویدن به مسافت ۲۰ کیلومتر موجب بروز خستگی کمتر و بازیابی سریعتر قوای بدنی گردد. همچنین بررسی‌ها نشان داده است که مصرف ۱۰۰ میلی گرم ال-کارنیتین به ازای هر کیلو وزن افراد و کودکان تالاسمی ماژور به مدت ۳ ماه موجب کاهش نیاز بدن این افراد به پالایش خون شود. ● منابع تامین ال کارنیتین در بدن از ترکیب دو اسیدآمینه لیزین و متیونین ساخته می شود. سلول‌های بدن برای سنتز کارنیتین به ویتامین‌های C، B۶ و B۳ (نیاسین) نیاز دارند. اما می توان آن را از منابع غذایی حیوانی مانند گوشت قرمز، لبنیات و آواکادو نیز دریافت کرد. غذاهای گیاهی منبع خوبی برای این ماده نمی‌باشند.L – کارنیتین یک دارو هم می‌باشد و برای درمان بیمارانی به‌کارمی‌رود که بدن آنها به اندازه کافی کارنیتین تولید نمی‌کند. اینک کاربرد آن را به‌عنوان راهی برای پیشگیری از صدماتی بررسی می‌کنند که در اثر کاربرد شیمی‌درمانی به بافت‌ها وارد می‌شود. ● موارد مصرف دارویی کمبود کارنیتین در برنامه‌های بدنسازی (تقویت عضلانی ) جلوگیری از کرامپ عضلانی در همودیالیز و کمک به بهبود عملکرد قلب. ● میزان مصرف: برای فرد ۵۰ کیلویی ۱ تا ۳ گرم همراه غذا به صورت قرص و شربت هم وجود دارد. مصرف ایزومر D کارنیتین بسیار محدود و فقط تحت نظز پزشک است. کارنیتین را طبق دستور پزشک و یا دستور زیر مصرف کنید: کمبود کارنیتین در افراد بالغ: ۹۹۰ میلی‌گرم، دو یا سه بار در روز درمان اثرات مصرف والپروئیک اسید: ۵۰ تا ۱۰۰ میلی‌گرن در روز در سه یا چهار وعده ● نازایی مردان: ۲ گرم ال کارنیتین به همراه ۱ گرم ال – استیل- کارنیتین در روز ● اثرات جانبی مصرف کارنیتین مصرف زیاد آن موجب شادی و سرخوشی نسبتاً کمی می شود که می تواند گهگاهی برای پیشرفت وضعیت ذهن و فکر ما مفید باشد. از دیگر اثرات جانبی کارنیتین باید گفت، اگر این ماده بیش از ۳۰۰۰ میلی گرم در روز مصرف شود، ممکن است بدن فرد، بوی ماهی بگیرد. حالت تهوع، اسهال، استفراغ و سردرد نیز در برخی افراد دیده شده است. ● مقدار مصرف: ال کارنیتین را معمولا به مقدار ۵٠٠تا ١٠٠٠میلیگرم ٣ بار در روز همراه هر وعده غذایی مصرف می کنند و به سه شکل قرص،کپسول و پودر موجود است. ● مزایای مصرف ال – کارنیتین: ال کارنیتین دو نوع تاثیر مهم در بدن دارد که یکی اثر چربی سوزی آن است و دیگری اثرات فیزیولوژیکی آن می باشد . - اثر چربی سوزی - تا ثیرات بر روی توده استخوان - اثرات آنتی اکسیدانی - بهبود بیماری های قلبی:( حملات قلبی، نا رسایی های قلبی، آنژین ها، بیماری عروق محیطی ، لنگی متناوب) - کمک به بیماران دیابتی - بهبود عملکرد ورزشکاران استقامتی - کاهش وزن - بهبود آلزایمر و بیماری اختلال حافظه - بیماری های کلیوی و دیالیز - ناباروری مردان - بهبود سندروم خستگی مزمن - بهبود بیماری جنون - کاهش استرس اکسیداتیو عوارض جانبی ال- کارنیتین : مصرف سطوح طبیعی کارنیتین برای شما عوارض جانبی ناخوشایندی به همراه نخواهد داشت . با این وجود ، شما ممکن است زمانی که آن را مصرف می کنید انرژی بیش از حد داشته باشید ، و اگر شما آن را بعد از ساعت ۴ عصر مصرف کنید ممکن است به اختلال درخواب شب دچار شوید. این اثرات جانبی واقعا دلایل مهمی برای نگرانی در افراد نیستند ، چون آنها اغلب خفیف تا متوسط ، و آسان برای مقابله می باشند. برخی از عوارض جانبی ال- کارنیتین که تا کنون گزارش شده شامل: استفراغ ، حالت تهوع ، سردرد ، اسهال ، آبریزش بینی ، بی قراری و مشکل خواب می باشند . برخی از عوارض جانبی جدی ممکن است بالا رفتن میزان سرعت ضربان قلب ، افزایش فشار خون و تب باشند. ● موارد منع مصرف : اگر فرد دچار کم کاری تیروئید است نباید ال کارنیتین مصرف کند چرا که با کار هورمونهای تیروئید تداخل می کند. همچنین در افرادی که دیالیز می شوند این ماده منع مصرف دارد. در افرادی که ال کارنیتین را برای کاهش وزن مصرف می کنند خطر بروز بی اشتهایی عصبی (anorexia nervosa) وجود دارد زیرا ال کارنیتین اشتها را کم می کند و حساسیت فرد به لاغر شدن میتواند نهایتا منجر به بی اشتهایی عصبی شده و سوء تغذیه شدید را به دنبال داشته باشد. ● مواد غذایی که کارنیتین در آنها وجود دارد: بالاترین غلظت کارنیتین در گوشت قرمز و محصولات لبنی یافت می شوند. سایر منابع طبیعی که کارنیتین در آنها وجود دارد ، شامل: آجیل و دانه ها (به عنوان مثال:، کدو، آفتابگردان، کنجد)، حبوبات (لوبیا ، نخود فرنگی ، عدس، بادام زمینی)، سبزیجات(مارچوبه، چغندر، سیب زمینی، کلم بروکلی، جوانه بروکسل ، سیر، خردل سبز، بامیه، جعفری، کلم پیچ) میوه (موز)، غلات (گندم سیاه، ذرت، ارزن، بلغور جو دوسر، سبوس برنج، گندم، سبوس گندم، جوانه گندم) و گرده عسل .

مطالعات نشان می دهد که ویتامین D حدود 3 درصد ژنوم انسان را تنظیم می کند . یک محقق ایرانی دراین زمینه می گوید: تحقیقات نشان داده است که رفع کمبود این ویتامین ، مرگ و میر را 11 درصد کاهش می دهد.
راحت ترین راه برای دریافت ویتامین D برای مردم این است که به اندازه کافی در معرض آفتاب قرار بگیرید. درواقع گیرنده های این ویتامین روی دی ان ای انسان است و این ویتامین بیان ژن ها را در بدن تنظیم می کند.

کمبود ویتامین D معمولا مشکلاتی مثل رماتیسم و پوکی استخوان را تداعی می کند و مانع از جذب کلسیم می شود.

در سال های اخیر شواهدی از امکان ارتباط کمبود آن با بیماری خطرناک ام اس مشاهده شده است . سال گذشته مطالعه ای حاکی از دامن زدن کمبود این ویتامین به افزایش ناتوانی جسمی در سنین بیشتر منتشر شد.

دو مطالعه تازه در نشریه بریتیش مدیکال ژورنال چاپ شده است که این کمبود را به دامنه وسیعتری از مشکلات جسمی گره می زند.

این مطالعات از جمله نشان می دهد که احتمال مرگ بر اثر سرطان و بیماری قلبی و ابتلا به سایر بیماری ها در افرادی که کمبود ویتامین D دارند بیشتر است.

دکتر امیر هادی مغزی از دانشگاه ایالتی کالیفرنیا در سانفرانسیسکو هر دو مطالعه را مهم می داند.

او می گوید: ˈبه نظرم هر دو مطالعه نشان می دهد که ویتامین D، به جز اثراتش در استخوان در بافت های دیگر هم اثر می گذارد. مطالعه اول در مورد مرگ و میر خیلی مطالعه جالبی است چون نشان می دهد که اگر کمبود ویتامین در جامعه حل شود، می توان از حدود 11 درصد از مرگ و میر جلوگیری کرد.ˈ

مطالعه اول را دکتر اسکار فرانکو استاد طب پیشگیری در مرکز پزشکی اراسموس در هلند هدایت کرده است.

فرانکو می گوید در سراسر بدن گیرنده های سلولی برای جذب ویتامین D هست که نشان دهنده اهمیت آن برای عملکرد فیزیولوژیکی بدن است.

به گفته او، نظریه هایی وجود دارد مبنی بر اینکه ویتامین D از ژن ها گرفته تا تورم در بدن را کنترل می کند.

مغزی در این بار می گوید: ˈمساله جالب در مورد ویتامین D این است که حدود سه درصد ژنوم انسان توسط این ویتامین تنظیم می شود. یعنی گیرنده های این ویتامین روی دی ان ای انسان هست و این ویتامین بیان ژن ها را تنظیم می کند.ˈ

هر دو مطالعه بر تحلیل داده های بیش از یک میلیون نفر استوار است.

فرانکو و همکارانش از دانشگاه های هاروارد، آکسفورد و سایر دانشگاه ها دریافتند که شواهد قانع کننده ای هست که ویتامین D در برابر بیماری های عمده از بدن محافظت می کند.

مغزی معتقد است: ˈاین دو مطالعه تمام تحقیقات قبلی چاپ شده تا امروز را بررسی کردند و اثرات خیلی مهمی که پیدا کردند در بیماری های قلبی عروقی، یک نوع سرطان یعنی در روده بزرگ، بیماری های مرتبط با روانپزشکی مثل افسردگی، بیماری های متابولیک مثل بیماری دیابت نوع دوم و حتی شواهدی مثل بیماری های اطفال پیدا کردند. چون این حجم نمونه بسیار زیادی است این مطالعات بسیار ارزش دارند اما چون محدودیت های خاص خود را دارند باید با احتیاط آنها را بررسی کرد.ˈ

براساس مطالعه اول، خطر مرگ در اثر بیماری قلبی در کسانی که کمبود این ویتامین داشتند 35 درصد بیشتر بود، خطر مرگ در اثر سرطان 14 درصد بیشتر و در مجموع خطر مرگ در افراد با کمبود این ویتامین بیشتر بود.

این مطالعات نشان داد مصرف قرص های ویتامین D از نوع 2 فایده ای ندارد اما ویتامین D 3 نوعی که در مواد غذایی و در اثر خورشید تولید می شود - برای میانسالان و سالخوردگان موثر بود.

در آمریکا و اروپا تخمین زده می شود که دو سوم جمعیت کمبود ویتامین D داشته باشند.

فرانکو و همکارانش حساب کرده اند که حدود 13 درصد کل مرگ ها در آمریکا و نه درصد آنها در اروپا را می تواند به کمبود ویتامین ِD نسبت داد.

نشریه بریتیش مدیکال جورنال در سرمقاله ای نوشته است که هنوز نباید مصرف مرتب قرص های ویتامین ِD را توصیه کرد مگر آنکه فواید و عوارض جانبی بالقوه آنها در آینده مشخص شود.

بنابراین، فعلا راحت ترین راه این است که به اندازه کافی آفتاب بگیرید.

پیشنهاد این پزشک این است که آفتاب گرفتن باید دو بار در هفته، هر بار نیم ساعت باشد. البته نگرانی هایی در مورد خطرات آن برای پوست وجود دارد بنابراین نباید در آفتاب گرفتن زیاده روی کرد.

هنوز معلوم نیست که کمبود ویتامین D مستقیما عامل بیماری است یا نشانگر رفتارهایی است که به ضعف سلامتی دامن می زند مثلا زیاد نشستن، سیگار کشیدن یا رژیم غذایی ناسالم.

Calcium is a mineral found in many foods. The body needs calcium to maintain strong bones and to carry out many important functions. Almost all calcium is stored in bones and teeth, where it supports their structure and hardness.

The body also needs calcium for muscles to move and for nerves to carry messages between the brain and every body part. In addition, calcium is used to help blood vessels move blood throughout the body and to help release hormones and enzymes that affect almost every function in the human body.
Table of Contents

    What is calcium and what does it do?
    How much calcium do I need?
    What foods provide calcium?
    What kinds of calcium dietary supplements are available?
    Am I getting enough calcium?
    What happens if I don't get enough calcium?
    What are some effects of calcium on health?
    Can calcium be harmful?
    Are there any interactions with calcium that I should know about?
    Calcium and healthful eating
    Where can I find out more about calcium?
    Disclaimer

How much calcium do I need?

The amount of calcium you need each day depends on your age. Average daily recommended amounts are listed below in milligrams (mg):
Life Stage     Recommended Amount
Birth to 6 months    200 mg
Infants 7–12 months    260 mg
Children 1–3 years    700 mg
Children 4–8 years    1,000 mg
Children 9–13 years    1,300 mg
Teens 14–18 years    1,300 mg
Adults 19–50 years    1,000 mg
Adult men 51–70 years    1,000 mg
Adult women 51–70 years    1,200 mg
Adults 71 years and older    1,200 mg
Pregnant and breastfeeding teens    1,300 mg
Pregnant and breastfeeding adults    1,000 mg
What foods provide calcium?

Calcium is found in many foods. You can get recommended amounts of calcium by eating a variety of foods, including the following:

    Milk, yogurt, and cheese are the main food sources of calcium for the majority of people in the United States.
    Kale, broccoli, and Chinese cabbage are fine vegetable sources of calcium.
    Fish with soft bones that you eat, such as canned sardines and salmon, are fine animal sources of calcium.
    Most grains (such as breads, pastas, and unfortified cereals), while not rich in calcium, add significant amounts of calcium to the diet because people eat them often or in large amounts.
    Calcium is added to some breakfast cereals, fruit juices, soy and rice beverages, and tofu. To find out whether these foods have calcium, check the product labels.

What kinds of calcium dietary supplements are available?

Calcium is found in many multivitamin-mineral supplements, though the amount varies by product. Dietary supplements that contain only calcium or calcium with other nutrients such as vitamin D are also available. Check the Supplement Facts label to determine the amount of calcium provided.

The two main forms of calcium dietary supplements are carbonate and citrate. Calcium carbonate is inexpensive, but is absorbed best when taken with food. Some over-the-counter antacid products, such as Tums® and Rolaids®, contain calcium carbonate. Each pill or chew provides 200–400 mg of calcium. Calcium citrate, a more expensive form of the supplement, is absorbed well on an empty or a full stomach. In addition, people with low levels of stomach acid (a condition more common in people older than 50) absorb calcium citrate more easily than calcium carbonate. Other forms of calcium in supplements and fortified foods include gluconate, lactate, and phosphate.

Calcium absorption is best when a person consumes no more than 500 mg at one time. So a person who takes 1,000 mg/day of calcium from supplements, for example, should split the dose rather than take it all at once.

Calcium supplements may cause gas, bloating, and constipation in some people. If any of these symptoms occur, try spreading out the calcium dose throughout the day, taking the supplement with meals, or changing the supplement brand or calcium form you take.
Am I getting enough calcium?

Many people don't get recommended amounts of calcium from the foods they eat, including:

    Boys aged 9 to 13 years,
    Girls aged 9 to 18 years,
    Women older than 50 years,
    Men older than 70 years.

When total intakes from both food and supplements are considered, many people—particularly adolescent girls—still fall short of getting enough calcium, while some older women likely get more than the safe upper limit. See our Health Professional Fact Sheet on Calcium for more details.

Certain groups of people are more likely than others to have trouble getting enough calcium:

    Postmenopausal women because they experience greater bone loss and do not absorb calcium as well. Sufficient calcium intake from food, and supplements if needed, can slow the rate of bone loss.
    Women of childbearing age whose menstrual periods stop (amenorrhea) because they exercise heavily, eat too little, or both. They need sufficient calcium to cope with the resulting decreased calcium absorption, increased calcium losses in the urine, and slowdown in the formation of new bone.
    People with lactose intolerance cannot digest this natural sugar found in milk and experience symptoms like bloating, gas, and diarrhea when they drink more than small amounts at a time. They usually can eat other calcium-rich dairy products that are low in lactose, such as yogurt and many cheeses, and drink lactose-reduced or lactose-free milk.
    Vegans (vegetarians who eat no animal products) and ovo-vegetarians (vegetarians who eat eggs but no dairy products), because they avoid the dairy products that are a major source of calcium in other people's diets.

Many factors can affect the amount of calcium absorbed from the digestive tract, including:

    Age. Efficiency of calcium absorption decreases as people age. Recommended calcium intakes are higher for people over age 70.
    Vitamin D intake. This vitamin, present in some foods and produced in the body when skin is exposed to sunlight, increases calcium absorption.
    Other components in food. Both oxalic acid (in some vegetables and beans) and phytic acid (in whole grains) can reduce calcium absorption. People who eat a variety of foods don't have to consider these factors. They are accounted for in the calcium recommended intakes, which take absorption into account.

Many factors can also affect how much calcium the body eliminates in urine, feces, and sweat. These include consumption of alcohol- and caffeine-containing beverages as well as intake of other nutrients (protein, sodium, potassium, and phosphorus). In most people, these factors have little effect on calcium status.
What happens if I don't get enough calcium?

Insufficient intakes of calcium do not produce obvious symptoms in the short term because the body maintains calcium levels in the blood by taking it from bone. Over the long term, intakes of calcium below recommended levels have health consequences, such as causing low bone mass (osteopenia) and increasing the risks of osteoporosis and bone fractures.

Symptoms of serious calcium deficiency include numbness and tingling in the fingers, convulsions, and abnormal heart rhythms that can lead to death if not corrected. These symptoms occur almost always in people with serious health problems or who are undergoing certain medical treatments.
What are some effects of calcium on health?

Scientists are studying calcium to understand how it affects health. Here are several examples of what this research has shown:

Bone health and osteoporosis
Bones need plenty of calcium and vitamin D throughout childhood and adolescence to reach their peak strength and calcium content by about age 30. After that, bones slowly lose calcium, but people can help reduce these losses by getting recommended amounts of calcium throughout adulthood and by having a healthy, active lifestyle that includes weight-bearing physical activity (such as walking and running).

Osteoporosis is a disease of the bones in older adults (especially women) in which the bones become porous, fragile, and more prone to fracture. Osteoporosis is a serious public health problem for more than 10 million adults over the age of 50 in the United States. Adequate calcium and vitamin D intakes as well as regular exercise are essential to keep bones healthy throughout life.

Cardiovascular Disease
Whether calcium affects the risk of cardiovascular disease is not clear. Some studies show that getting enough calcium might protect people from heart disease and stroke. But other studies show that some people who consume high amounts of calcium, particularly from supplements, might have an increased risk of heart disease. More research is needed in this area.

High blood pressure
Some studies have found that getting recommended intakes of calcium can reduce the risk of developing high blood pressure (hypertension). One large study in particular found that eating a diet high in fat-free and low-fat dairy products, vegetables, and fruits lowered blood pressure.

Cancer
Studies have examined whether calcium supplements or diets high in calcium might lower the risks of developing cancer of the colon or rectum or increase the risk of prostate cancer. The research to date provides no clear answers. Given that cancer develops over many years, longer term studies are needed.

Kidney stones
Most kidney stones are rich in calcium oxalate. Some studies have found that higher intakes of calcium from dietary supplements are linked to a greater risk of kidney stones, especially among older adults. But calcium from foods does not appear to cause kidney stones. For most people, other factors (such as not drinking enough fluids) probably have a larger effect on the risk of kidney stones than calcium intake.

Weight loss
Although several studies have shown that getting more calcium helps lower body weight or reduce weight gain over time, most studies have found that calcium—from foods or dietary supplements—has little if any effect on body weight and amount of body fat.
Can calcium be harmful?

Getting too much calcium can cause constipation. It might also interfere with the body's ability to absorb iron and zinc, but this effect is not well established. In adults, too much calcium (from dietary supplements but not food) might increase the risk of kidney stones. Some studies show that people who consume high amounts of calcium might have increased risks of prostate cancer and heart disease, but more research is needed to understand these possible links.

The safe upper limits for calcium are listed below. Most people do not get amounts above the upper limits from food alone; excess intakes usually come from the use of calcium supplements. Surveys show that some older women in the United States probably get amounts somewhat above the upper limit since the use of calcium supplements is common among these women.
Life Stage     Upper Safe Limit
Birth to 6 months    1,000 mg
Infants 7–12 months    1,500 mg
Children 1–8 years    2,500 mg
Children 9–18 years    3,000 mg
Adults 19–50 years    2,500 mg
Adults 51 years and older    2,000 mg
Pregnant and breastfeeding teens    3,000 mg
Pregnant and breastfeeding adults    2,500 mg
Are there any interactions with calcium that I should know about?

Calcium dietary supplements can interact or interfere with certain medicines that you take, and some medicines can lower or raise calcium levels in the body. Here are some examples:

    Calcium can reduce the absorption of these drugs when taken together:
        Bisphosphonates (to treat osteoporosis)
        Antibiotics of the fluoroquinolone and tetracycline families
        Levothyroxine (to treat low thyroid activity)
        Phenytoin (an anticonvulsant)
        Tiludronate disodium (to treat Paget's disease).
    Diuretics differ in their effects. Thiazide-type diuretics (such as Diuril® and Lozol®) reduce calcium excretion by the kidneys which in turn can raise blood calcium levels too high. But loop diuretics (such as Lasix® and Bumex®) increase calcium excretion and thereby lower blood calcium levels.
    Antacids containing aluminum or magnesium increase calcium loss in the urine.
    Mineral oil and stimulant laxatives reduce calcium absorption.
    Glucocorticoids (such as prednisone) can cause calcium depletion and eventually osteoporosis when people use them for months at a time.

Tell your doctor, pharmacist, and other health care providers about any dietary supplements and medicines you take. They can tell you if those dietary supplements might interact or interfere with your prescription or over-the-counter medicines or if the medicines might interfere with how your body absorbs, uses, or breaks down nutrients.
Calcium and healthful eating

People should get most of their nutrients from food, advises the federal government's Dietary Guidelines for Americans. Foods contain vitamins, minerals, dietary fiber and other substances that benefit health. Dietary supplements might help in some situations to increase the intake of a specific vitamin or mineral. For more information on building a healthy diet, refer to the Dietary Guidelines for Americansexternal link icon and the U.S. Department of Agriculture's food guidance system, ChooseMyPlateexternal link icon.