Vitamin C (Ascorbic acid)

Vitamin C is a water-soluble vitamin, meaning that your body doesn't store it. We get what we need, instead, from food. 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 essential for healing wounds, and for repairing and maintaining bones and teeth.

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, which occur naturally when our bodies transform food into energy. The build-up of free radicals over time may be largely responsible for the aging process and can contribute to the development of health conditions such as cancer, heart disease, and arthritis.

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 that it may help protect arteries against damage.

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.

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, the scientific evidence doesn't support the notion. 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 (evaluating groups of people over time) 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 is protecting 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. Moreover, 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 a 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, that said, 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.

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 pre-term 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 immune system function
• 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

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 U.S. recommended dietary allowances), are listed below.

Pediatric

• Birth - 6 months: 40 mg
• Infants 6 - 12 months: 50 mg
• 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
• Breastfeeding women: 120 mg

Because smoking depletes vitamin C, people who smoke generally need an additional 35 mg per day.

The doses recommended to prevent or treat many of the conditions mentioned in the Uses section is often 500 - 1,000 mg per day.