Taking carnitine with omega-3 fish oil is one of the simplest things you can do to lose weight and raise your energy levels. The cool thing about carnitine is that by elevating the amount of carnitine stored in your muscles, you will see improvements in your quality of life. Fat loss and more energy are two of these benefits, but taking carnitine is known to improve all of the following:
• High-intensity work capacity
• Increase athletic performance
• Speed your recovery from intense exercise
• Make your brain work better
• Prevent oxidative stress that leads to longer term health problems such as cardiovascular disease, diabetes, and chronic inflammation
A recent study in The Journal of Physiology provides groundbreaking evidence that carnitine supplementation can improve athletic performance, something that researchers have had trouble proving for years. Emerging research on the benefits of carnitine for health in conjunction with evidence that clarifies the best ways to take carnitine (insulin must be present in the body for carnitine to be delivered into the muscle), make it time to revisit this amino acid. Let’s look at the top ten health benefits of elevating your carnitine levels with a focus on achieving optimal body composition.
1) Take Carnitine to Burn Fat: The Basics
Carnitine is an amino acid composite that is made from lysine and methionine. There are a couple of different forms of carnitine, such as acetyl-L-carnitine and L-carnitine tartrate, and we’ll look at which forms you should be taking and when. In this article, unless otherwise stated, “carnitine” will be used to refer to L-carnitine tartrate.
Carnitine is a potent fat burner because it is responsible for the transport of fats into the cells to be used for energy in the body. By raising the level of muscle carnitine, you support the fat burning process, and because your body becomes more efficient at processing fuel, it will increase your energy levels. Elevating carnitine will also improve physical performance by burning more fat, sparing glycogen, clearing muscle lactate, and increasing anabolic hormone response.
2) Pair Carnitine and Omega-3 Fish Oils For Fat Loss
For carnitine to be effective, you need to ensure you have adequate levels of omega-3 fish oils in the body. In order for your body to actually “load” carnitine that you take in supplement form into the muscles where you want it, it has to be accompanied by insulin.
Omega-3 fatty acids come into the equation because they will improve the health of every cell in your body if you get enough of them. The cells are made up of two layers of lipids or fats, which will be composed of good fats or bad fats depending on the type you eat. If the cell lipid layers are made up of omega-3s, the cell will be generally healthier, and it will also make them more sensitive to insulin. Having your cells be more sensitive to insulin allows your body to get the most energy production out of supplemental carnitine.
I mention this relationship between omega-3s and carnitine because you won’t optimally benefit from taking carnitine unless you have already attended to your omega-3s. In working with obese clients, I’ve found that using high doses of fish oil with carnitine tartrate will allow the fat to start to come off.
Omega-3s increase metabolic rate by increasing cell activity and fat burning. Carnitine is the delivery system for long chain fatty acids such that the less carnitine you have in the body, the fewer fatty acids that get into the cell, meaning you don’t burn them for energy. Instead, the fatty acids go into a depository and are stored as fat. By elevating carnitine, fat burning increases and you give the cell the right genetic machinery to raise metabolism. You’ll have more energy, feel more motivated, and any excess fat begins to come off.
3) No Need For Carbs: Carnitine with Omega-3s for Fat Loss
The new study in The Journal of Physiology, which we will highlight below starting with #5, showed that taking carnitine with carbs is effective for elevating muscle carnitine levels and improving athletic performance. But carbs aren’t necessary as long as you get adequate omega-3s. A study in the Annals of Nutrition and Metabolism showed that combining carnitine, omega-3s, and polyphenols resulted in lower blood lipid levels and better cellular energy production, which has the implication of fat loss if the study had been of longer duration—it was only 12 weeks.
Researchers found that triglycerides were lowered by 24 percent and free fatty acids decreased by 29 percent compared to a placebo group that had no changes. These changes indicate healthier markers of cholesterol, better energy use, and fat burning that will lead to fat loss. Additionally, genes that increase fat burning in the body were “activated” indicating a better metabolic profile. Take note that the polyphenols were included to raise antioxidant levels and fight oxidative stress that leads to chronic inflammation and poor cardiovascular health, among other things. They are not necessary for the carnitine to work its magic.
4) Carnitine Fights Visceral Belly Fat
Visceral belly fat is one of the toughest fats to lose once you’ve got it, and it causes numerous health problems. Once you begin to gain visceral fat around the belly, it will lead to fat gain within the organs such as the liver, the heart, or even in muscle. Fat gain in the liver leads to non-alcoholic fatty liver disease, while epicardial fat is a type of visceral fat that is deposited around the heart and is considered a metabolically active organ, altering heart function.
Raising your carnitine levels will fight this visceral fat gain because it increases fat burning, which has the effect of taking triglycerides and low-density lipoproteins out of the system so that they don’t build up causing high cholesterol and atherosclerosis. A new research study in the journal Food and Chemical Toxicology illustrates this. Researchers gave a carnitine supplement to mice who were fed a high-fat diet in order to make them gain weight. In comparison to a group of mice fed a placebo, the carnitine group gained substantially less visceral and subcutaneous fat (fat that is right below the surface of the skin that you can pinch with your fingers). The placebo group exhibited the beginning stages of non-alcoholic fatty liver disease and atherosclerosis, neither of which were evident in the carnitine group.
5) Take Carnitine To Improve Performance
The study in The Journal of Physiology is the first to show that muscle carnitine content can be increased in humans through diet . Once carnitine is elevated, metabolism in the body is dependent on the intensity of exercise, allowing for better energy use and performance.
Researchers gave a placebo or a supplement of carnitine tartrate and carbs (2 g carnitine with 80 g of carbs twice a day) to experienced athletes who were training for a triathlon three to five times a week. At various points throughout the study subjects performed the following exercise tests: two thirty-minute repeated bouts of exercise (the first at 50 percent of maximal oxygen uptake and the second at 80 percent), followed by an all-out 30-minute performance trial.
After 24 weeks of supplementation, the carnitine group increased performance from baseline by 11 percent in the exercise trials compared to no improvement in the placebo group. Participants who took carnitine also rated the trial and the exercise bout they performed at 80 percent of max to be easier than at baseline, while the placebo had no difference in rating of perceived exertion (RPE).
Two key points from this study are essential for making carnitine supplementation effective at elevating performance. First, it takes a long supplementation period to raise muscle carnitine levels and reap the benefits of improved energy production. In this study after three months there were no changes in performance or RPE from baseline, but after 6 months those improvements were pronounced and statistically significant. Somewhere between 3 and 6 months is the magic number, meaning taking carnitine is a lifestyle supplement just like omega-3s are.
Second, carnitine doesn’t accumulate or “load” in muscle unless accompanied by high insulin concentrations. This explains why many previous studies have NOT shown increases in muscle carnitine after taking it in multi-gram doses. In this study the carnitine was taken with carbs because the carbs triggered insulin release, which allowed the carnitine to load into the muscle. Take note that there is a big focus in the health world on minimizing insulin secretion from carbs for optimal body composition. This is critical, but be aware that insulin is actually a potent anabolic hormone if the cells are sensitive to it and if appropriate levels are present.
Pairing carnitine with carbs is one option, but as shown in #3, carnitine can also be paired with omega-3s, which may be more appropriate for individuals whose primary goal is to lose fat. In my experience, best fat loss results come from a 5 to 1 ratio of omega-3s to carnitine. If you’re taking 20 grams of omega-3s, you’d pair it with 4 grams of carnitine. But, if you’re more conservative with your omega-3 supplementation, you can start with 1 to 2 grams of carnitine and work up to 4 grams, which was the dose used in this study.
6) Increase Work Capacity With Carnitine
Another benefit of raising carnitine levels is that you’ll have a greater work capacity, but it will not feel as physically difficult. You’ll be able to lift more weight, complete more reps, or run faster and longer, but with more ease. This is because higher muscle carnitine levels help decreases pain, muscle damage, and markers of metabolic stress from high-intensity exercise by decreasing lactic acid production.
A higher level of carnitine increases energy production, but it also has the effect of accelerating muscle buffering by maintaining the pH of the muscle and minimizing the accumulation of hydrogen ions. Basically, carnitine helps eliminate the byproducts of intense exercise that cause pain and muscle damage (the burning you may feel when training hard), allowing you to work harder.
In the Journal of Physiology study, results show how higher muscle carnitine levels increase work capacity by reducing lactate accumulation in the muscles. Following the exercise bout at 80 percent of maximal, muscle lactate buildup was 44 percent lower in participants that supplemented with carnitine compared to the control group. Following the exercise bout at 50 percent of maximal, the carnitine group used 55 percent less muscle glycogen than the control group indicating that they burned more fat for fuel and had improved energy production. ??
The combination of less lactate buildup and greater fat burning in the two exercise bouts allowed the carnitine group to increase work output by 35 percent, while having a lower RPE. In simple terms, taking carnitine is a no-brainer if you want to improve body composition by burning more fat and be able to train at a higher level!
7) Enhance Recovery with Carnitine
Take carnitine to speed both short- and long-term recovery from intense training and you’ll have less pain, soreness, and feel more energized. Muscle lactate buildup is a limiting factor that inhibits performance and causes muscle pain, meaning that if you produce less of it and are able to clear it faster, you will have a faster recovery.
Taking carnitine will also support an anabolic response to exercise by up-regulating the androgen receptors, which will “help to mediate quicker recovery,” according to one research group. Two studies led by William J. Kraemer tested the hormonal response to taking carnitine tartrate. In one of these studies, supplementing with carnitine for 21 days produced an increase in the resting content of the androgen receptors that bind with testosterone, indicating a better anabolic environment. Following resistance exercise, participants also had increased androgen receptor content that indicated greater cellular uptake of testosterone and increased protein synthesis. Enhanced protein synthesis allows tissue that was damaged during training to regenerate faster and speed recovery.
The second study also had participants take carnitine or a placebo for 21 days and found that after intense resistance training, the carnitine group had reduced muscle tissue damage (assessed by MRI) and increased IGFBP-3 levels (a binding protein that promotes tissue synthesis). Researchers suggest carnitine supplementation helps promote recovery by producing “more undamaged tissue, (and a) greater number of intact receptors that would be available for hormonal interactions.”
8) Improve Cognitive Performance with Acetyl-L-Carnitine and Increase Motivation
A form of carnitine called acetyl-l-carnitine will give you superior brain function and increase motivation, meaning it’s a great supplement for people who want to lose weight but feel unmotivated to exercise. Acetyl-l-carnitine helps DHA omega-3 fish oils work their magic on the brain—just like carnitine tartrate, this form needs to be taken with omega-3s in order to facilitate fat burning for energy in the brain.
Acetyl-l-carnitine is a powerful antioxidant and can detoxify the brain of heavy metals we suggest pairing it with Alpha Lipoic Acid along with DHA because all together they support dopamine levels, while increasing attention span and motivation. For depressed people or those who need to lose weight, it works wonders on motivation and self-initiative, both with training and work-related tasks. And by taking acetyl-l-carnitine, you’ll still benefit from improved energy, physical performance, work capacity, and a speedy recovery, all benefits to help you achieve a lean physique.
A number of research studies support the use of acetyl-l-carnitine for a better brain. For example, a new study in the Scandinavian Journal of Gastroenterology found that giving patients with liver dysfunction acetyl-l-carnitine significantly improved their physical function, general health, overall mood, and well-being. They also reported less depression and anxiety.
9) Prevent Type 2 Diabetes and Improve Insulin Health With Carnitine
Carnitine is emerging as a supplement that can prevent type 2 diabetes because of how it improves fat metabolism. It can counter the diseases of metabolic syndrome by preventing atherosclerosis, and supporting cardiovascular health, while inducing fat loss.
Plus, raising carnitine levels will fight related type 2 diabetes factors because it has antioxidant properties, meaning it abolishes free radicals and reduces oxidative stress. The key to improving your insulin health and losing fat with carnitine is to understand that the following interrelated factors must be present for this method to be effective:
A) Take carnitine with omega-3 fish oils. Remember, a 1 to 5 ratio is suggested.
B) Adopt this supplementation protocol as a lifestyle habit, not a one time thing. Research shows androgen receptors are up-regulated after three weeks, triglycerides are improved after three months, but muscle carnitine level isn’t elevated for close to six months.
C) A high-protein diet and exercise will make it much more effective
10) Carnitine Supplementation Counters Cachexia or Wasting Disease
Raising carnitine levels can counter cachexia or wasting syndrome that is associated with diseases including cancer, AIDS, heart disease, and lung disease. Although this is not a common problem among the Poliquin readership, it should be mentioned here because carnitine supplementation is able to restore metabolic parameters in individuals with cachexia and thereby help fight the progression of life-threatening diseases.
Cachexia is characterized by progressive weight loss, muscle loss, cognitive decline, poor insulin health, inflammation, and poor organ function, among other things. Emerging evidence shows that in patients with cancer cachexia, carnitine is depleted and metabolism is impaired. A new study in Nutrition Journal found that giving carnitine to men with pancreatic cancer who were suffering from cachexia improved their lean mass, increased energy metabolism, and improved their quality of life. Using carnitine produced a trend to increased survival over the course of the study and towards reduced hospital stays.
11) Take Carnitine to Improve Male Fertility
Having adequate carnitine levels has been shown to be necessary for male fertility. One study found that fertile males had higher levels of carnitine and this was associated with healthier sperm. The men who were classified as infertile had lower carnitine and compromised sperm health. This study suggests that ensuring you have get adequate carnitine in conjunction with healthy lifestyle practices can support fertility.
12) Use Carnitine for Better Skin
A topical carnitine cream can improve the health of your skin by decreasing the amount of oil released by the pores. A new study in the Journal of Cosmetic Dermatology found that a carnitine cream increased the amount of fat that entered the cell, which decreased the oil secreted by the skin. This led to less oily skin and a smoother overall appearance. It also indicates the value of using carnitine to improve the transport of carnitine across the cellular wall to be burned for fat because Beta fat oxidation, or burning, was enhanced.
Vitamin B12, also called cobalamin, is one of 8 B vitamins. All B vitamins help the body convert food (carbohydrates) into fuel (glucose), which is used to produce energy. These B vitamins, often referred to as B complex vitamins, also help the body use fats and protein. B complex vitamins are needed for healthy skin, hair, eyes, and liver. They also help the nervous system function properly.
All B vitamins are water soluble, meaning that the body does not store them.
Vitamin B12 is an especially important vitamin for maintaining healthy nerve cells, and it helps in the production of DNA and RNA, the body's genetic material. Vitamin B12 works closely with vitamin B9, also called folate or folic acid, to help make red blood cells and to help iron work better in the body. Folate and B12 work together to produce S-adenosylmethionine (SAMe), a compound involved in immune function and mood.
Vitamins B12, B6, and B9 work together to control blood levels of the amino acid homocysteine. High levels of homocysteine are associated with heart disease. However, researchers are not sure whether homocysteine is a cause of heart disease or just a marker that indicates someone may have heart disease.
It is rare for young people to be deficient in vitamin B12, but it is not uncommon for older people to be mildly deficient. This may be because their diets are not as healthy, or because they have less stomach acid, which the body needs to absorb B12. Low levels of B12 can cause a range of symptoms including:
Fatigue
Shortness of breath
Diarrhea
Nervousness
Numbness
Tingling sensation in the fingers and toes
Severe deficiency of B12 causes nerve damage.
Others at risk for B12 deficiency include:
Vegans and vegetarians who do not eat dairy or eggs, since vitamin B12 is found only in animal products
People with problems absorbing nutrients due to Crohn disease, pancreatic disease, weight loss surgery, or medications
People who are infected with Helicobacter pylori, an organism in the intestines that can cause an ulcer. H. pylori damages stomach cells that make intrinsic factor, a substance the body needs to absorb B12
People with an eating disorder
People with HIV
People with diabetes
The elderly
Folic acid (vitamin B9), especially when taken in high doses, can mask the symptoms of a vitamin B12 deficiency. The danger is that without symptoms, someone with a vitamin B12 deficiency may not know it, and could run the risk of developing nerve damage. You should talk to your doctor first if you plan to take more than 800 mcg of folic acid, to make sure you do not have a B12 deficiency.
Vitamin B12 is used for:
Pernicious anemia
Pernicious anemia is a type of anemia that happens when stomach cells are not able to make intrinsic factor. Without intrinsic factor, your body cannot absorb vitamin B12. Symptoms include:
Weakness
Pale skin
Diarrhea
Weight loss
Fever
Numbness or tingling sensation in the hands and feet
Loss of balance
Confusion, memory loss, and moodiness
Vitamin B12 supplements in high doses, either given as injections or orally, are prescribed to treat pernicious anemia. Pernicious anemia can be a dangerous condition and should always be treated by a doctor.
Heart disease
Many studies suggest that people with high levels of the amino acid homocysteine are almost two times more likely to develop coronary artery disease and 2.5 times more likely to have a stroke than those with normal levels. B complex vitamins, especially vitamins B9, B6, and B12, help lower homocysteine levels. However, researchers do not know whether high homocysteine levels actually cause heart disease.
People who are concerned about heart disease should try to get enough B vitamins from healthy foods. However, in some cases doctors recommend taking B vitamins to lower homocysteine levels. If you are worried about heart disease, ask your doctor whether taking a B vitamin supplement would be right for you.
Age-related macular degeneration (AMD)
One large study found that women who took 1,000 mcg of vitamin B12, along with 2500 mcg of folic acid and 500 mg of vitamin B6 daily, reduced the risk of developing AMD, an eye disease that can cause loss of vision.
Fatigue
Fatigue is one of the symptoms of a vitamin B12 deficiency. One small study suggested that some people who were not deficient in B12 might gain more energy from B12 shots. However, more research is needed. One preliminary study indicated that people with chronic fatigue syndrome might benefit from B12 injections. More research is needed.
Breast cancer
Although there is no evidence that vitamin B12 alone reduces the risk of breast cancer, population studies have shown that women who get more folate in their diet have lower risk of breast cancer. Vitamin B12 works with folate in the body, so it may help reduce breast cancer risk. Another preliminary study suggested that postmenopausal women who had the lowest amounts of B12 in their diet had an increased risk for breast cancer.
Male infertility
Studies suggest that vitamin B12 supplements may improve sperm counts and sperm's ability to swim. More research is needed.
Dietary Sources
Vitamin B12 is found only in animal foods. Good dietary sources include:
Fish
Shellfish
Dairy products
Organ meats, particularly liver and kidney
Eggs
Beef
Pork
Available Forms
Vitamin B12 can be found in multivitamins (including children's chewable and liquid drops), B complex vitamins, and individual supplements. Vitamin B12 is available in intranasal forms (administered through the nose), as well as oral tablets, capsules, soft gels, and lozenges. Vitamin B12 is also sold under the names cobalamin and cyanocobalamin.
How to Take It
If your diet includes meat, fish or shellfish, milk, and other dairy products, you should be able to meet the recommended daily requirements without taking a vitamin B12 supplement. Vegetarians who do not eat any animal products should take a vitamin B12 supplement with water, preferably after eating. Elderly people may need larger amounts of vitamin B12 than younger people because the body's ability to absorb vitamin B12 from the diet declines with age.
If you are considering taking a B12 supplement, ask your health care provider to help you determine the right dose for you.
Daily recommendations for dietary vitamin B12 are listed below.
Pediatric
Newborns to 6 months: 0.4 mcg (adequate intake)
Infants 6 months to 1 year: 0.5 mcg (adequate intake)
Children 1 to 3 years: 0.9 mcg (RDA)
Children 4 to 8 years: 1.2 mcg (RDA)
Children 9 to 13 years: 1.8 mcg (RDA)
Teens 14 to 18 years: 2.4 mcg (RDA)
Adult
19 years and older: 2.4 mcg (RDA)*
Pregnant women: 2.6 mcg (RDA)
Breastfeeding women: 2.8 mcg (RDA)
*Because 10 to 30% of older people may not absorb B12 from food very well, people over 50 should meet their daily requirement through either foods fortified with vitamin B12 or a supplement containing B12.
Precautions
Because of the potential for side effects and interactions with medications, you should take dietary supplements only under the supervision of a knowledgeable health care provider.
Vitamin B12 is considered safe and nontoxic, however taking any one of the B vitamins for a long period of time can result in an imbalance of other important B vitamins. For this reason, you may want to take a B complex vitamin that includes all B vitamins. Taking folic acid at high doses can hide a vitamin B12 deficiency. So these vitamins are often taken together. Talk to your doctor before taking more than 800 mcg of folic acid.
People with abnormal levels of red blood cells, or abnormalities in their red blood cells, should work with a doctor to determine whether B12 is appropriate for them. In some instances, B12 can be beneficial. But it can be harmful with other health conditions. For instance, B12 supplements can cause serious damage to the optic nerve in people with Leber's disease (a disease of the eye). Again, be sure to work with your doctor.
Possible Interactions
If you are currently being treated with any of the following medications, you should not use vitamin B12 supplements without first talking to your health care provider.
Medications that reduce levels of B12 in the body include:
Anti-seizure medications -- including phenytoin (Dilantin), phenobarbital, primidone (Mysoline)
Chemotherapy medications -- particularly methotrexate
Colchicine -- used to treat gout
Bile acid sequestrants -- used to lower cholesterol; include colestipol (Colestid), cholestyramine (Questran), and colsevelam (Welchol)
H2 blockers -- used to reduce stomach acid; include cimetidine (Tagamet), famotidine (Pepcid AC), ranitidine (Zantac)
Metformin (Glucophage) -- medication taken for diabetes
Proton pump inhibitors -- used to reduce stomach acid; include esomeprazole (Nexium), lansprazole (Prevacid), omeprazole (Prilosec), rabeprazole (Aciphex)
Antibiotics, Tetracycline: Vitamin B12 should not be taken at the same time as
Turmeric is a perennial plant of the ginger family, native to southwest India. Turmeric is commonly consumed in powder form and used as a spice.
To make turmeric powder, the leaves of the plant are boiled for 30-45 minutes, dried in ovens and then ground into a deep orange-yellow powder. Turmeric powder is a common spice used in Indian and Pakistani cuisine. It is a major component of curry and can also be used for dyeing cloth.
There are three naturally occurring phytochemicals in turmeric: curcumin, demethoxycurcumin and bisdemothoxycurcumin, together referred to as curcuminoids.
This MNT Knowledge Center feature is part of a collection of articles on the health benefits of popular foods. It provides a nutritional breakdown of turmeric and an in-depth look at its possible health benefits, how to incorporate more turmeric into your diet and any potential health risks of consuming turmeric.
Contents of this article:
Nutritional breakdown of turmeric, possible health benefits
Further health benefits, how to incorporate more turmeric into your diet, possible risks
Nutritional breakdown of turmericTurmeric root and powder.
According to the USDA National Nutrient Database, one tablespoon of turmeric powder contains 29 calories, 0.9 grams of protein, 0.3 grams of fat and 6.3 grams of carbohydrates (including 2 grams of fiber and 0.3 grams of sugar).1
That same 1 tablespoon serving provides 26% of your daily manganese needs, 16% of iron, 5% of potassium and 3% of vitamin C.
Turmeric has traditionally been used in Ayurvedic and Chinese medicine to treat inflammatory conditions, skin diseases, wounds, digestive ailments and liver conditions.
Possible benefits of consuming turmeric
Curcumin is the active substance in turmeric believed to be the source of its many health benefits. Curcumin is also responsible for turmeric's distinctly earthy, slightly bitter and peppery flavor.
Digestion
Curcumin may help improve digestion by stimulating the gallbladder to produce bile. A double-blind, placebo-controlled study showed that turmeric reduced bloating and gas in people suffering from indigestion. The German Commission E, a group that determines which herbs can safely be prescribed in Germany, has approved the use of turmeric for digestive problems.2
Are you getting enough vitamin B12? Many people don’t, and that deficiency can cause problems.
Vitamin B12 does a lot of things for your body. It helps make your DNA and your red blood cells, for examples.
You can get vitamin B12 from your diet, or from supplements. Exactly how much you need depends on your age.
assorted vitamins
Causes of Vitamin B12 Deficiency
Vitamin B12 deficiency can happen if you have certain conditions, such as:
Atrophic gastritis, in which your stomach lining has thinned
Pernicious anemia, which makes it hard for your body to absorb vitamin B12
Surgery that removed part of your stomach or small intestine, including weight loss surgery
Conditions affecting the small intestine, such as Crohn's disease, celiac disease, bacterial growth, or a parasite
Heavy drinking
Immune system disorders, such as Graves' disease or lupus
Long-term use of acid-reducing drugs
Does vitamin A do anything to help eyes and vision? Can a vitamin A deficiency cause blindness? Is it dangerous to consume too much vitamin A?
Read on for answers to these questions and other useful facts about this important antioxidant vitamin, including information about eye benefits of vitamin A and beta carotene, top vitamin A foods, and possible benefits of vitamin A eye drops.
What Is Vitamin A?
Vitamin A actually is a group of antioxidant compounds that play an important role in vision, bone growth and health of the immune system. Vitamin A also helps the surface of the eye, mucous membranes and skin be effective barriers to bacteria and viruses, reducing the risk of eye infections, respiratory problems and other infectious diseases.
In general, there are two types of vitamin A, depending on the type of food source it comes from:
Sweet potatoes and carrots are excellent sources or provitamin A carotenoids that are good for your eyes.
Vitamin A from animal-derived foods is called retinol. This "pre-formed" vitamin A can be used directly by the body. Good food sources of retinol vitamin A include beef and chicken liver, whole milk and cheese.
Vitamin A obtained from colorful fruits and vegetables is in the form of "provitamin A" carotenoids, which are converted to retinol by the body after the food is ingested. Good food sources of provitamin A carotenoids include carrots, sweet potatoes, spinach, kale and cantaloupes.
Beta carotene is one of the most prevalent and effective provitamin A carotenoids.
Eye Benefits of Vitamin A and Beta Carotene
Because vitamin A helps protect the surface of the eye (cornea), it is essential for good vision.
Studies show vitamin A eye drops are effective for the treatment of dry eyes. In fact, one study found that over-the-counter lubricating eye drops containing vitamin A were as effective for the treatment of dry eye syndrome as more expensive prescription eye drops formulated for dry eye relief.
Vitamin A eye drops also have been shown effective for the treatment of a specific type of eye inflammation called superior limbic keratoconjunctivitis.
Vitamin A, at least when in combination with other antioxidant vitamins, also appears to play a role in decreasing the risk of macular degeneration (AMD). In the landmark Age-Related Eye Disease Study (AREDS) sponsored by the National Eye Institute, people at high risk for the disease who took a daily multiple vitamin that included vitamin A (as beta carotene), vitamin C, vitamin E, zinc and copper had a 25 percent reduced risk of advanced AMD during a six-year period.
It also appears that a combination of vitamin A and lutein may prolong vision in people suffering from retinitis pigmentosa (RP). A recent four-year study conducted by researchers from Harvard Medical School and other prominent universities found that individuals with retinitis pigmentosa who took daily supplements of vitamin A (15,000 IU) and lutein (12 mg) had a slower loss of peripheral vision than those who did not take the combined supplements.
Because beta carotene is converted into vitamin A in the body, it's likely beta carotene (provitamin A) offers similar eye benefits as the pre-formed retinol type of vitamin A, though more research is needed to confirm this.
In early 2011, researchers at Columbia University Medical Center (New York) found that a synthetic, altered form of vitamin A might be able to slow the progression of Stargardt's disease, an inherited eye disease that causes severe vision loss in young people.
When given to mice with the same genetic defect as humans with Stargardt's disease (also called juvenile macular degeneration), the modified vitamin A inhibited the growth of clump-like deposits in the retina called "vitamin A dimers" that are associated with degenerative changes and vision loss.
The National Eye Institute has awarded the researchers a $1.25 million grant to further investigate the link between vitamin A dimers and various retinal degenerations, which could lead to new approaches to treat these diseases.
Also, Alkeus Pharmaceuticals (Cambridge, Mass.) has licensed certain patents from Columbia University related to the research and is planning to launch clinical trials for the treatment of Stargardt's disease and macular degeneration with modified vitamin A in the near future.
Vitamin A Deficiency
Vitamin A deficiency is rare in the United States, but it is common among the poor in developing countries. It's estimated that approximately 250,000 to 500,000 malnourished children worldwide become blind each year due to vitamin A deficiency that could have been prevented with a proper diet.
One of the first signs of vitamin A deficiency is night blindness. In ancient Egypt, it was discovered that night blindness could be cured by eating liver, which later was found to be a rich source of vitamin A.
A lack of vitamin A causes the cornea to become very dry, leading to clouding of the front of the eye, corneal ulcers and vision loss. Vitamin A deficiency also causes damage to the retina, which also contributes to blindness.
Because vitamin A also is important for resistance to infection and a healthy immune system, vitamin A deficiency can lead to death from respiratory and other infections.
Vitamin C is a water-soluble vitamin, meaning that your body doesn't store it. You have to get what you need from food, including citrus fruits, broccoli, and tomatoes.
You need vitamin C for the growth and repair of tissues in all parts of your body. It helps the body make collagen, an important protein used to make skin, cartilage, tendons, ligaments, and blood vessels. Vitamin C is needed for healing wounds, and for repairing and maintaining bones and teeth. It also helps the body absorb iron from nonheme sources.
Vitamin C is an antioxidant, along with vitamin E, beta-carotene, and many other plant-based nutrients. Antioxidants block some of the damage caused by free radicals, substances that damage DNA. The build up of free radicals over time may contribute to the aging process and the development of health conditions such as cancer, heart disease, and arthritis.
It’s rare to be seriously deficient in vitamin C, although evidence suggests that many people may have low levels of vitamin C. Smoking cigarettes lowers the amount of vitamin C in the body, so smokers are at a higher risk of deficiency.
Signs of vitamin deficiency include dry and splitting hair; gingivitis (inflammation of the gums) and bleeding gums; rough, dry, scaly skin; decreased wound-healing rate, easy bruising; nosebleeds; and a decreased ability to ward off infection. A severe form of vitamin C deficiency is known as scurvy.
Low levels of vitamin C have been associated with a number of conditions, including high blood pressure, gallbladder disease, stroke, some cancers, and atherosclerosis, the build up of plaque in blood vessels that can lead to heart attack and stroke. Getting enough vitamin C from your diet -- by eating lots of fruit and vegetables -- may help reduce the risk of developing some of these conditions. There is no conclusive evidence that taking vitamin C supplements will help or prevent any of these conditions.
Vitamin C plays a role in protecting against the following:
Heart Disease
Results of scientific studies on whether vitamin C is helpful for preventing heart attack or stroke are mixed. Vitamin C doesn't lower cholesterol levels or reduce the overall risk of heart attack, but evidence suggests it may help protect arteries against damage.
Some studies -- though not all -- suggest that vitamin C can slow down the progression of atherosclerosis (hardening of the arteries). It helps prevent damage to LDL ("bad") cholesterol, which then builds up as plaque in the arteries and can cause heart attack or stroke. Other studies suggest that vitamin C may help keep arteries flexible.
In addition, people who have low levels of vitamin C may be more likely to have a heart attack, stroke, or peripheral artery disease, all potential results of having atherosclerosis. Peripheral artery disease is the term used to describe atherosclerosis of the blood vessels to the legs. This can lead to pain when walking, known as intermittent claudication. But there is no evidence that taking vitamin C supplements will help.
The best thing to do is get enough vitamin C through your diet. That way, you also get the benefit of other antioxidants and nutrients contained in food. If you have low levels of vitamin C and have trouble getting enough through the foods you eat, ask your doctor about taking a supplement.
High Blood Pressure
Population-based studies (which involve observing large groups of people over time) suggest that people who eat foods rich in antioxidants, including vitamin C, have a lower risk of high blood pressure than people who have poorer diets. Eating foods rich in vitamin C is important for your overall health, especially if you are at risk for high blood pressure. The diet physicians most frequently recommend for treatment and prevention of high blood pressure, known as the DASH (Dietary Approaches to Stop Hypertension) diet, includes lots of fruits and vegetables, which are loaded with antioxidants.
Common Cold
Despite the popular belief that vitamin C can cure the common cold, scientific evidence doesn't support that theory. Taking vitamin C supplements regularly (not just at the beginning of a cold) produces only a small reduction in the duration of a cold (about 1 day). The only other piece of evidence supporting vitamin C for preventing colds comes from studies examining people exercising in extreme environments (athletes, such as skiers and marathon runners, and soldiers in the Arctic). In these studies, vitamin C did seem to reduce the risk of getting a cold.
Cancer
Results of many population-based studies suggest that eating foods rich in vitamin C may be associated with lower rates of cancer, including skin cancer, cervical dysplasia (changes to the cervix which may be cancerous or precancerous, picked up by pap smear), and, possibly, breast cancer. But these foods also contain many beneficial nutrients and antioxidants, not only vitamin C, so it's impossible to say for certain that vitamin C protects against cancer. Taking vitamin C supplements, on the other hand, has not been shown to have any helpful effect.
In addition, there is no evidence that taking large doses of vitamin C once diagnosed with cancer will help your treatment. In fact, some doctors are concerned that large doses of antioxidants from supplements could interfere with chemotherapy medications. More research is needed. If you are undergoing chemotherapy, talk to your doctor before taking vitamin C or any supplement.
Osteoarthritis
Vitamin C is essential for the body to make collagen, which is part of normal cartilage. Cartilage is destroyed in osteoarthritis (OA), putting pressure on bones and joints. In addition, some researchers think free radicals -- molecules produced by the body that can damage cells and DNA -- may also be involved in the destruction of cartilage. Antioxidants such as vitamin C appear to limit the damage caused by free radicals. However, no evidence suggests that taking vitamin C supplements will help treat or prevent OA. What the evidence does show is that people who eat diets rich in vitamin C are less likely to be diagnosed with arthritis.
Taking nonsteroidal anti-inflammatory drugs can lower your levels of vitamin C. If you take these drugs regularly for OA, you might want to take a vitamin C supplement.
Age-related Macular Degeneration
Vitamin C (500 mg) appears to work with other antioxidants, including zinc (80 mg), beta-carotene (15 mg), and vitamin E (400 IU) to protect the eyes against developing macular degeneration (AMD), the leading cause of legal blindness in people over 55 in the United States. The people who seem to benefit are those with advanced AMD. It isn't known whether this combination of nutrients helps prevent AMD or is beneficial for people with less advanced AMD. This combination includes a high dose of zinc, which you should only take under a doctor’s supervision.
Pre-eclampsia
Some studies suggest that taking vitamin C along with vitamin E may help prevent pre-eclampsia in women who are at high risk. Pre-eclampsia, characterized by high blood pressure and too much protein in the urine, is a common cause of premature births. Not all studies agree, however.
Asthma
Studies are mixed when it comes to the effect of vitamin C on asthma. Some show that low levels of vitamin C are more common in people with asthma, leading some researchers to think that low levels of vitamin C might increase the risk for this condition. Other studies seem to show that vitamin C may help reduce symptoms of exercise-induced asthma.
Other
Although the information is limited, studies suggest that vitamin C may also be helpful for:
- Boosting immunity
- Maintaining healthy gums
- Improving vision for those with uveitis (an inflammation of the middle part of the eye)
- Treating allergy-related conditions, such as asthma, eczema, and hay fever (called allergic rhinitis)
- Reducing effects of sun exposure, such as sunburn or redness (called erythema)
- Alleviating dry mouth, particularly from antidepressant medications (a common side effect from these drugs)
- Healing burns and wounds
- Decreasing blood sugar in people with diabetes
- Some viral conditions, including mononucleosis -- Although scientific evidence is lacking, some doctors may suggest high-dose vitamin C to treat some viruses
Dietary Sources
Excellent sources of vitamin C include oranges, green peppers, watermelon, papaya, grapefruit, cantaloupe, strawberries, kiwi, mango, broccoli, tomatoes, Brussels sprouts, cauliflower, cabbage, and citrus juices or juices fortified with vitamin C. Raw and cooked leafy greens (turnip greens, spinach), red and green peppers, canned and fresh tomatoes, potatoes, winter squash, raspberries, blueberries, cranberries, and pineapple are also rich sources of vitamin C. Vitamin C is sensitive to light, air, and heat, so you'll get the most vitamin C if you eat fruits and vegetables raw or lightly cooked.
Available Forms
You can purchase either natural or synthetic vitamin C, also called ascorbic acid, in a variety of forms. Tablets, capsules, and chewables are probably the most popular forms, but vitamin C also comes in powdered crystalline, effervescent, and liquid forms. Vitamin C comes in doses ranging from 25 - 1,000 mg.
"Buffered" vitamin C is also available if you find that regular ascorbic acid upsets your stomach. An esterified form of vitamin C is also available, which may be easier on the stomach for those who are prone to heartburn.
How to Take It
The best way to take vitamin C supplements is 2 - 3 times per day, with meals, depending on the dosage. Some studies suggest that adults should take 250 - 500 mg twice a day for any benefit. Talk to your doctor before taking more than 1,000 mg of vitamin C on a daily basis and before giving vitamin C to a child.
Daily intake of dietary vitamin C (according to the National Academy of Sciences) is listed below.
Pediatric
- Birth - 6 months: 40 mg (Adequate intake)
- Infants 6 - 12 months: 50 mg (Adequate intake)
- Children 1 - 3 years: 15 mg
- Children 4 - 8 years: 25 mg
- Children 9 - 13 years: 45 mg
- Adolescent girls 14 - 18 years: 65 mg
- Adolescent boys 14 - 18 years: 75 mg
Adult
- Men over 18 years: 90 mg
- Women over 18 years: 75 mg
- Pregnant women 14 - 18 years: 80 mg
- Pregnant women over 18 years: 85 mg
- Breastfeeding women 14 - 18 years: 115 mg
- Breastfeeding women over 18 years: 120 mg
Because smoking depletes vitamin C, people who smoke may need an additional 35 mg per day.
The dose recommended to prevent or treat many of the conditions mentioned in the Uses section is often 500 - 1,000 mg per day.
Precautions
Because of the potential for side effects and interactions with medications, you should take dietary supplements only under the supervision of a knowledgeable health care provider.
Vitamin C supplements have a diuretic effect, meaning the help the body get rid of excess fluid. Be sure to drink plenty of fluids when taking them.
Most commercial vitamin C is made from corn. People sensitive to corn should look for alternative sources, such as sago palm.
Vitamin C increases the amount of iron absorbed from foods. People with hemochromatosis, an inherited condition where too much iron builds up in the body, should not take vitamin C supplements.
Vitamin C is generally considered safe because your body gets rid of what it does not use. But at high doses (more than 2,000 mg daily) it can cause diarrhea, gas, or stomach upset. If you experience these side effects, lower the dose of vitamin C.
People with kidney problems should talk to their doctor before taking vitamin C.
People who smoke or use nicotine patches may need more vitamin C because nicotine makes vitamin C less effective in the body.
Infants born to mothers taking 6,000 mg or more of vitamin C may develop rebound scurvy because their intake of vitamin C drops after birth. If you are pregnant, talk to your doctor before taking more than 1,000 mg of vitamin C.
People with sickle cell anemia, as well as people with a metabolic disorder called G6PD, can potentially have serious side-effects from taking high levels of vitamin C.
Thalassemia and Hemochromatosis patients could be negatively affected by increased iron absorption, which may occur from vitamin C supplementation.
Vitamin C may raise blood sugar levels in people with diabetes. In older women with diabetes, doses of vitamin C above 300 mg per day were associated with an increased risk of death from heart disease.
Taking vitamin C right before or after angioplasty may interfere with healing.
If you are being treated for cancer, talk to your oncologist before taking vitamin C. Vitamin C may potentially interact with some chemotherapy drugs