Health Matters
Ask Dr. Lo
Vitamin C and the Possible Benefits For You
Vitamin C, also known as ascorbic acid, is a water-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 can also be exposed to free radicals in the environment from cigarette smoke, air pollution, car exhaust, etc.
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.
What Foods Provide Vitamin C?
Fruits and vegetables are the best sources of vitamin C. You can get the recommended amounts of vitamin C by eating a variety of foods, including citrus fruits (such as oranges and grapefruits), as well as red and green peppers and kiwifruit, which have a lot of vitamin C.
Other fruits and vegetables, such as broccoli, strawberries, cantaloupe, baked potatoes, Brussel sprouts, and tomatoes also have vitamin C.
The vitamin C content of food can be reduced by prolonged storage and by cooking. Steaming or microwaving may lessen cooking losses. Many of the best food sources of vitamin C, such as fruits and vegetables, can be 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.
Am I Getting Enough Vitamin C?
Most people in the United States get enough vitamin C from the foods they eat. However, certain groups of people are more likely 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.
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 limited variety of foods may also need additional Vitamin C added to their diet.
People with certain medical conditions such as severe malabsorption, some types of cancer, and kidney disease, requiring hemodialysis, also need additional Vitamin C.
What Happens If I Don’t Get Enough Vitamin C?
Vitamin C deficiency is rare in the United States. People who get little or no vitamin C 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 of the Effects of Vitamin C On Health?
Scientists are studying vitamin C to understand how it affects health. Here are examples of what 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, vitamin C supplements have not been proven to protect people from 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 cannot raise blood levels of vitamin C nearly as high as intravenous doses. A few studies in animals and test tubes indicate that very high blood levels of vitamin C might shrink tumors. However, more research is needed to determine whether high-dose intravenous vitamin C helps treat cancer in people.
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.
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 slow AMD progression.
In a large study among older people with AMD who were at high risk of developing advanced AMD, those 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 six years had a lower chance of developing advanced AMD. They also had less vision loss than those who did not take the dietary supplement.
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.
The common cold. It seems that people who take vitamin C supplements regularly might have slightly shorter colds or somewhat milder symptoms when they do have a cold.
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 daily upper limits for vitamin C include intakes from all sources—food and supplements—and are: 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.
Does Vitamin C Interact With Medications or Other Dietary Supplements?
Vitamin C dietary supplements can interact or interfere with medicines that you take. 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 and healthy beverages. Foods contain vitamins, minerals, dietary fiber, and other components that benefit health. In some cases, fortified foods and dietary supplements are useful when it is not possible to meet needs for one or more nutrients (for example, during specific life stages such as pregnancy).
*Source: Office of Dietary Suplements (ODS).
