Vitamin C, also known as ascorbic acid and L-ascorbic acid, is a vitamin found in food and used as a dietary supplement. The disease scurvy is prevented and treated with vitamin C containing foods or dietary supplements. Evidence does not support use in the general population for the prevention of the common cold. There is, however, some evidence that regular use may shorten the length of colds. It is unclear if supplementation affects the risk of cancer, heart disease, or dementia. It may be taken by mouth or by injection.

Vitamin C is generally well tolerated. Large doses may cause gastrointestinal discomfort, headache, trouble sleeping, and flushing of the skin. Normal doses are safe during pregnancy. The United States Institute of Medicine recommends against taking large doses.

Ball-and-stick model of L-ascorbic acid
Ball-and-stick model of L-ascorbic acid

Vitamin C is an essential nutrient involved in the repair of tissue and the making of certain neurotransmitters. It is required for the functioning of several enzymes and is important for immune system function. It is within the class of chemicals known as antioxidants. Foods containing vitamin C include citrus fruits, broccoli, Brussels sprouts, raw bell peppers, and strawberries. Prolonged storage or cooking may reduce vitamin C content in foods.

Vitamin C was discovered in 1912, isolated in 1928 and first made in 1933, making it the first vitamin to be manufactured. It is on the World Health Organization’s List of Essential Medicines, the most effective and safe medicines needed in a health system. Vitamin C is available as a generic medication and over the counter. In 2015, the wholesale cost in the developing world was less than US$0.01 per tablet. Partly for its discovery, Albert Szent-Györgyi and Walter Norman Haworth were awarded the 1937 Nobel Prize.

Natta projection of structural formula for L-ascorbic acid
Natta projection of structural formula for L-ascorbic acid

Uses of Vitamin C

Vitamin C has a definitive role in treating scurvy, which is a disease caused by vitamin C deficiency. Beyond that, a role for vitamin C as prevention or treatment for various diseases is disputed, with reviews reporting conflicting results. A 2012 Cochrane review reported no effect of vitamin C supplementation on overall mortality. It is on the World Health Organization’s List of Essential Medicines as one of the most effective and safe medicines needed in a health system.

Side effects of Vitamin C

More than two to three grams may cause indigestion, particularly when taken on an empty stomach. However, taking vitamin C in the form of sodium ascorbate and calcium ascorbate may minimize this effect. Other symptoms reported for large dose include nausea, abdominal cramps and diarrhea. These effects are attributed to the osmotic effect of unabsorbed vitamin C passing through the intestine. In theory, high vitamin C intake may cause excessive absorption of iron. A summary of reviews of supplementation in healthy subjects did not report this problem, but left as untested the possibility that individuals with hereditary hemochromatosis might by adversely affected. There is a longstanding belief among the mainstream medical community that vitamin C increases risk of kidney stones. “Reports of kidney stone formation associated with excess ascorbic acid intake are limited to individuals with renal disease”. Reviews state that “data from epidemiological studies do not support an association between excess ascorbic acid intake and kidney stone formation in apparently healthy individuals”, although one large, multi-year trial did report a nearly two-fold increase in kidney stones in men who regularly consumed a vitamin C supplement. Vitamin C is a water-soluble vitamin, with dietary excesses not absorbed, and excesses in the blood rapidly excreted in the urine, so it exhibits remarkably low acute toxicity.

Recommended levels of Vitamin C

    Recommendations for vitamin C intake by adults have been set by various national agencies:

  • 40 milligrams per day: India National Institute of Nutrition, Hyderabad
  • 45 milligrams per day or 300 milligrams per week: the World Health Organization
  • 80 milligrams per day: the European Commission Council on nutrition labeling
  • 90 mg/day (males) and 75 mg/day (females): Health Canada 2007
  • 90 mg/day (males) and 75 mg/day (females): United States National Academy of Sciences.
  • 100 milligrams per day: Japan National Institute of Health and Nutrition.
  • 110 mg/day (males) and 95 mg/day (females): European Food Safety Authority


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