Vitamin C

Publication Date: 
Tue, 11/08/2011
By: Alere Staff

Vitamin C, also known as ascorbic acid, is a water-soluble vitamin found naturally in many fruits and vegetables. It represents the body's most powerful water soluble antioxidant.1 In addition to its antioxidant functions, vitamin C plays an important role in immune function1 and improves the absorption of nonheme iron.2

Vitamin C plays a key role in the body and is being studied in:

  • Cancer (including prevention and treatment)1
  • Cardiovascular disease1
  • Age-related macular degeneration (AMD) and cataracts3
  • Common cold4

Where is Vitamin C found?

Several foods provide vitamin C including citrus fruits, tomatoes and tomato juice, and potatoes are among the best sources. Dietary supplements are also a source of vitamin C, although most experts recommend getting vitamin C from a diet high in fruits and vegetables rather than taking supplements.5 

Interaction with Warfarin

Vitamin C may affect your INR levels, so keep your vitamin C intake consistent.6 The cold and flu season is often a time when people consume larger quantities of vitamin C. If you are a 'seasonal' vitamin C consumer, be aware that more frequent testing might be warranted. Mechanical heart valve patients, in particular, who begin taking large doses of vitamin C run the risk of going sub-therapeutic without notice.7

Communication to your doctor prior to starting or stopping vitamin supplements is a must. Many other factors need to be considered to determine the affect of starting or stopping vitamin C intake. As always, discuss all diet and supplement changes with your doctor.

  1. Jacob RA, Sotoudeh G. Vitamin C function and status in chronic disease. Nutr Clin Care 2002;5:66-74.
  2. Gershoff SN. Vitamin C (ascorbic acid): new roles, new requirements? Nutr Rev 1993;51:313-26.
  3. Carr AC, Frei B. Toward a new recommended dietary allowance for vitamin C based on antioxidant and health effects in humans. Am J Clin Nutr 1999;69:1086-107.
  4. Douglas RM, Hemilä H. Vitamin C for preventing and treating the common cold. PLoS Med 2005;2:e168.
  5. U.S. Department of Agriculture. USDA National Nutrient Database for Standard Reference Release 23. 2010.
  6. Smith EC, Skalski RJ, Johnson GC, Rossi GV. Interaction of ascorbic acid and warfarin. JAMA 1972;221:1166.
  7. Jellin F, et al. Natural Medicines Comprehensive Database. 2005. p.1268.