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
Many people may take drinking water for granted, but keeping hydrated can have a huge impact on overall health. Despite how crucial it is that people drink enough water, a significant amount of people may be failing to drink recommended levels of fluids each day.
Woman drinking water.
The Institute of Medicine recommend that men achieve a daily fluid intake of around 3 liters and that women take in 2.2 liters.
Around of 70% of the body is comprised of water, and around of 71% of the planet's surface is covered by water. Perhaps it is the ubiquitous nature of water that means that drinking enough of it each day is not at the top of many people's lists of healthy priorities?
One part of the body that relies on adequate water intake is the kidneys. The kidneys are organs that might not get as much attention as the heart or lungs, but they are responsible for many functions that help keep the body as healthy as possible.
But what happens to the kidneys when we do not drink enough water? And what can be done to improve our levels of hydration? On World Kidney Day, we take a look at the role of drinking enough water for two of the most important organs in the body.
Why do we need to drink water?
Water is needed by all the cells and organs in the body in order for them to function properly. It is also used to lubricate the joints, protect the spinal cord and other sensitive tissues, regulate body temperature and assist the passage of food through the intestines.
Although some of the water required by the body is obtained through foods with a high water content - soups, tomatoes, oranges - the majority is gained through drinking water and other beverages.
During normal everyday functioning, water is lost by the body, and this needs to be replaced. It is noticeable that we lose water through activities such as sweating and urination, but water is even lost when breathing.
Drinking water, be it from the tap or a bottle, is the best source of fluid for the body. Beverages such as milk and juices are also decent sources of water, but beverages containing alcohol and caffeine, such as soft drinks, coffee and beer, are less than ideal due to having diuretic properties, meaning that they cause the body to release water.
How much water should you drink?
The recommended amount of water that should be drunk per day varies from person to person depending on factors such as how active they are and how much they sweat. There is no universally agreed upon threshold of water consumption that must be reached, but there is a general level of consensus as to what a healthy amount is.
According to the Institute of Medicine (IOM), an adequate intake for men is approximately 13 cups (3 liters) a day. For women, an adequate intake is around 9 cups (2.2 liters).
Many people may have heard the phrase, "Drink eight 8-ounce glasses of water a day," which works out at around 1.9 liters and is close to the IOM's recommendation for women. Drinking "8 by 8" is an easy-to-remember amount that can put people on the right track in terms of water consumption.
Water also helps dissolve minerals and nutrients so that they are more accessible to the body, as well as helping transport waste products out of the body. It is these two functions that make water so vital to the kidneys.
What do the kidneys do?
The kidneys are two small fist-sized organs that are shaped like beans. They are located in the middle of the back, on either side of the spine and situated just below the rib cage.
Despite their importance, the kidneys can sometimes receive less attention than other organs in the body. "The role of the kidneys is often underrated when we think about our health," state Kidney Health Australia.
Cross-section of the kidneys.
The role of the kidneys in keeping the body healthy may be underrated in relation to the heart and the lungs.
"In fact, the kidneys play an important role in the daily workings of our body. They are so important to health that nature gave us two kidneys to cover the possibility that one might be lost to an injury. They are so important that with no kidney function, death occurs within a few days."
A crucial function of the kidneys is to remove waste products and excess fluid from the body via urine. The kidneys also regulate the levels of salt, potassium and acid in the body and produce hormones that influence the performance of other organs.
When we eat and drink, nutrients and minerals enter the bloodstream in order to be transported around the body and used for energy, growth, maintenance or repair. The blood also passes through the kidneys where it is filtered, and any waste products and excess nutrients and water are removed and sent to the bladder for expulsion.
Every day, the kidneys filter around 200 quarts of fluid. Of these, approximately 2 quarts are removed from the body in the form of urine, and 198 are recovered by the bloodstream.
If the kidneys do not function properly through kidney disease, waste products and excess fluid can build up inside the body. Untreated, chronic kidney disease can lead to kidney failure, whereby the organs stop working, and either dialysis or kidney transplantation is required.
Water is important for the workings of the kidneys, not only for helping to initially dissolve the nutrients, but for ensuring that waste products, bacteria and proteins do not build up in the kidneys and the bladder. These can lead to dangerous infections and painful kidney stones.
How does not drinking enough affect the kidneys?
Urinary tract infections (UTIs) are the second most common type of infection in the body and account for around 8.1 million visits to health care providers in the US every year. If infections spread to the upper urinary tract, including the kidneys, permanent damage can be caused. Sudden kidney infections (acute) can be life-threatening, particularly if septicemia occurs.
Drinking plenty of water is one of the simplest ways to reduce the risk of developing a UTI and is also advised for people that have developed an infection.
The presence of kidney stones can complicate UTIs as they can compromise how the kidneys work. Complicated UTIs tend to require longer periods of antibiotics to treat them, typically lasting between 7 and 14 days.
The leading cause of kidney stones is a lack of water, and they are commonly reported in people that have been found not drinking the recommended daily amount of water. As well as complicating UTIs, research has suggested that kidney stones also increase the risk of chronic kidney disease developing.
In November 2014, the American College of Physicians issued new guidelines for people who have previously developed kidney stones, stating that increasing fluid intake to enable 2 liters of urination a day could decrease the risk of stone recurrence by at least half with no side effects.
Dehydration - using and losing more water than the body takes in - can also lead to an imbalance in the body's electrolytes. Electrolytes, such as potassium, phosphate and sodium, help carry electrical signals between cells. The levels of electrolytes in the body are kept stable by properly functioning kidneys.
When the kidneys are unable to maintain a balance in the levels of electrolytes, these electrical signals become mixed up, which can lead to seizures, involving involuntary muscle movements and loss of consciousness.
In severe cases, dehydration can also lead to kidney failure, a potentially life-threatening outcome. Possible complications of chronic kidney failure include anemia, damage to the central nervous system, heart failure and a compromised immune system.
There are a considerable number of health problems that can occur simply through not drinking enough water, and yet researchers have found that a significant number of Americans may be failing to obtain the recommended levels of fluid intake every day.
Does the US not drink enough water?
A study carried out by the Centers for Disease Control and Prevention (CDC) in 2013 analyzed data from the National Cancer Institute's 2007 Food Attitudes and Behaviors Survey, in order to assess the characteristics of people who have a low intake of drinking water.
People were more likely to drink less than 4 cups of drinking water daily if they consumed 1 cup or less of fruits or vegetables a day. The study indicates that among this sample, a large number of people may well have not been drinking the suggested 8 cups of fluid a day.
Although the study only measured the intake of drinking water and fluid can be gained from other beverages, water is the ideal source of fluid due to it being readily available, calorie-free, caffeine-free and alcohol-free.
The fact that 7% of respondents reported drinking no water at all daily, and that respondents who drank low volumes of water were associated with low levels of fruit and vegetable consumption, would suggest there is a certain number of people who are risking their health by not getting enough fluid.
Even if the respondents reporting low levels of water intake were obtaining enough fluid, it is likely that they would be obtaining it from sources that could potentially compromise their health in other ways.
"The biologic requirement for water may be met with plain water or via foods and other beverages," write the study authors. "Results from previous epidemiologic studies indicate that water intake may be inversely related to volume of calorically sweetened beverages and other fluid intake."
Vitamin E is a fat-soluble nutrient found in many 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 E to boost its immune system so that it can fight off invading bacteria and viruses. It helps to widen blood vessels and keep blood from clotting within them. In addition, cells use vitamin E to interact with each other and to carry out many important functions.
Table of Contents
What is vitamin E and what does it do?
How much vitamin E do I need?
What foods provide vitamin E?
What kinds of vitamin E dietary supplements are available?
Am I getting enough vitamin E?
What happens if I don't get enough vitamin E?
What are some effects of vitamin E on health?
Can vitamin E be harmful?
Are there any interactions with vitamin E that I should know about?
Vitamin E and healthful eating
Where can I find out more about vitamin E?
Disclaimer
How much vitamin E do I need?
The amount of vitamin E you need each day depends on your age. Average daily recommended intakes are listed below in milligrams (mg) and in International Units (IU). Package labels list the amount of vitamin E in foods and dietary supplements in IU.
Life Stage Recommended Amount
Birth to 6 months 4 mg (6 IU)
Infants 7–12 months 5 mg (7.5 IU)
Children 1–3 years 6 mg (9 IU)
Children 4–8 years 7 mg (10.4 IU)
Children 9–13 years 11 mg (16.4 IU)
Teens 14–18 years 15 mg (22.4 IU)
Adults 15 mg (22.4 IU)
Pregnant teens and women 15 mg (22.4 IU)
Breastfeeding teens and women 19 mg (28.4 IU)
What foods provide vitamin E?
Vitamin E is found naturally in foods and is added to some fortified foods. You can get recommended amounts of vitamin E by eating a variety of foods including the following:
Vegetable oils like wheat germ, sunflower, and safflower oils are among the best sources of vitamin E. Corn and soybean oils also provide some vitamin E.
Nuts (such as peanuts, hazelnuts, and, especially, almonds) and seeds (like sunflower seeds) are also among the best sources of vitamin E.
Green vegetables, such as spinach and broccoli, provide some vitamin E.
Food companies add vitamin E to some breakfast cereals, fruit juices, margarines and spreads, and other foods. To find out which ones have vitamin E, check the product labels.
What kinds of vitamin E dietary supplements are available?
Vitamin E supplements come in different amounts and forms. Two main things to consider when choosing a vitamin E supplement are:
The amount of vitamin E: Most once-daily multivitamin-mineral supplements provide about 30 IU of vitamin E, whereas vitamin E-only supplements usually contain 100 to 1,000 IU per pill. The doses in vitamin E-only supplements are much higher than the recommended amounts. Some people take large doses because they believe or hope that doing so will keep them healthy or lower their risk of certain diseases.
The form of vitamin E: Although vitamin E sounds like a single substance, it is actually the name of eight related compounds in food, including alpha-tocopherol. Each form has a different potency, or level of activity in the body.
Vitamin E from natural (food) sources is listed as "d-alpha-tocopherol" on food packaging and supplement labels. Synthetic (laboratory-made) vitamin E is listed as "dl-alpha-tocopherol." The natural form is more potent. For example, 100 IU of natural vitamin E is equal to about 150 IU of the synthetic form.
Some vitamin E supplements provide other forms of the vitamin, such as gamma-tocopherol, tocotrienols, and mixed tocopherols. Scientists do not know if any of these forms are superior to alpha-tocopherol in supplements.
Am I getting enough vitamin E?
The diets of most Americans provide less than the recommended amounts of vitamin E. Nevertheless, healthy people rarely show any clear signs that they are not getting enough vitamin E (see next question for information on the signs of vitamin E deficiency).
What happens if I don't get enough vitamin E?
Vitamin E deficiency is very rare in healthy people. It is almost always linked to certain diseases where fat is not properly digested or absorbed. Examples include Crohn's disease, cystic fibrosis, and certain rare genetic diseases such as abetalipoproteinemia and ataxia with vitamin E deficiency (AVED). Vitamin E needs some fat for the digestive system to absorb it.
Vitamin E deficiency can cause nerve and muscle damage that results in loss of feeling in the arms and legs, loss of body movement control, muscle weakness, and vision problems. Another sign of deficiency is a weakened immune system.
What are some effects of vitamin E on health?
Scientists are studying vitamin E to understand how it affects health. Here are several examples of what this research has shown.
Heart disease
Some studies link higher intakes of vitamin E from supplements to lower chances of developing heart disease. But the best research finds no benefit. People in these studies are randomly assigned to take vitamin E or a placebo (dummy pill with no vitamin E or active ingredients) and they don't know which they are taking. Vitamin E supplements do not seem to prevent heart disease, reduce its severity, or affect the risk of death from this disease. Scientists do not know whether high intakes of vitamin E might protect the heart in younger, healthier people who do not have a high risk of heart disease.
Cancer
Most research indicates that vitamin E does not help prevent cancer and may be harmful in some cases. Large doses of vitamin E have not consistently reduced the risk of colon and breast cancer in studies, for example. A large study found that taking vitamin E supplements (400 IU/day) for several years increased the risk of developing prostate cancer in men. Two studies that followed middle-aged men and women for 7 or more years found that extra vitamin E (300–400 IU/day, on average) did not protect them from any form of cancer. However, one study found a link between the use of vitamin E supplements for 10 years or more and a lower risk of death from bladder cancer.
Vitamin E dietary supplements and other antioxidants might interact with chemotherapy and radiation therapy. People undergoing these treatments should talk with their doctor or oncologist before taking vitamin E or other antioxidant supplements, especially in high doses.
Eye disorders
Age-related macular degeneration (AMD), or the loss of central vision in older people, and cataracts are among the most common causes of vision loss in older people. The results of research on whether vitamin E can help prevent these conditions are inconsistent. Among people with early-stage AMD, a supplement containing large doses of vitamin E combined with other antioxidants, zinc, and copper showed promise for slowing down the rate of vision loss.
Mental function
Several studies have investigated whether vitamin E supplements might help older adults remain mentally alert and active as well as prevent or slow the decline of mental function and Alzheimer's disease. So far, the research provides little evidence that taking vitamin E supplements can help healthy people or people with mild mental functioning problems to maintain brain health.
Can vitamin E be harmful?
Eating vitamin E in foods is not risky or harmful. In supplement form, high doses of vitamin E might increase the risk of bleeding (by reducing the blood's ability to form clots after a cut or injury) and of serious bleeding in the brain (known as hemorrhagic stroke). The highest safe level of intake from supplements for adults is 1,500 IU/day for natural forms of vitamin E and 1,100 IU/day for the synthetic form. The highest safe levels for children are lower than for adults. Some recent research suggests that intakes of vitamin E below these upper safe levels could increase the risk of prostate cancer in men. Vitamin E might also increase the risk of death in some adults with chronic health conditions, but this does not seem to be the case in healthy people.
Are there any interactions with vitamin E that I should know about?
Vitamin E dietary supplements can interact or interfere with certain medicines that you take. Here are some examples:
Vitamin E can increase the risk of bleeding in people taking anticoagulant or antiplatelet medicines, such as warfarin (Coumadin®).
In one study, vitamin E plus other antioxidants (such as vitamin C, selenium, and beta-carotene) reduced the heart-protective effects of two drugs taken in combination (a statin and niacin) to affect blood-cholesterol levels.
Taking antioxidant supplements while undergoing chemotherapy or radiation therapy for cancer could alter the effectiveness of these treatments.
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 E 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.