Vitamin C for Sports & Fitness

Also known as: Ascorbate, Ascorbic Acid

What is it?

Vitamin C is a water-soluble vitamin that has a number of biological functions.

Where is it found?

Broccoli, red peppers, currants, Brussel sprouts, parsley, potatoes, citrus fruit, and strawberries are good sources of vitamin C.

Why do athletes use it?*

Some athletes say that vitamin C

helps keep the immune system functioning optimally.
decreases recovery time between workouts.

What do the advocates say?*

Vitamin C is important for connective tissue repair. Although beneficial to athletes participating in a variety of sports, vitamin C is especially important to body builders whose training causes the most connective tissue damage.

Vitamin C is also important to athletes because, as an anti-oxidant, it may help to reverse some of the oxidative damage that may occur from exercise. This oxidative damage, caused by free radicals, may interfere with the cells’ ability to function normally and is believed to play a role in many different health conditions, including the aging process, cancer, and heart disease.

Vitamin C promotes a healthy immune system and may help to prevent the dip in immune function that may occur right after exercise.

How much is usually taken by athletes?

Placebo-controlled research, some of it double-blind, has shown that taking 400 to 3,000 mg of vitamin C per day for a few days before and after intense exercise may reduce pain and speed up muscle strength recovery.¹ ² ³ However, taking vitamin C only after such exercise was not effective in another double-blind study.⁴

In most well-controlled studies, exercise performance has not been shown to improve following supplementation with vitamin C, unless a deficiency exists, as might occur in athletes with unhealthy or irrational eating patterns.⁵ ⁶ Similarly, vitamin E has not benefited exercise performance, ⁷ ⁸ except possibly at high altitudes.⁹ ¹⁰

Are there any side effects or interactions?

Some people develop diarrhoea after as little as a few grams of vitamin C per day, while others are not bothered by ten times this amount. Strong scientific evidence to define and defend an upper tolerable limit for vitamin C is not available. A review of the available research concluded that high intakes (2–4 grams per day) are well-tolerated by healthy people.¹¹ However, intake of large amounts of vitamin C can deplete the body of copper¹² ¹³ —an essential nutrient. People should be sure to maintain adequate copper intake at higher intakes of vitamin C. Copper is found in many multivitamin-mineral supplements. Vitamin C increases the absorption of iron and should be avoided by people with iron overload diseases (e.g., haemochromatosis, haemosiderosis). Vitamin C helps recycle the anti-oxidant, vitamin E.

It is widely (and mistakenly) believed that mothers who consume large amounts of vitamin C during pregnancy are at risk of giving birth to an baby with a higher-than-normal requirement for the vitamin. The concern is that the baby could suffer “rebound scurvy,” a vitamin C deficiency caused by not having this increased need met. Even some medical textbooks have subscribed to this theory.¹⁴ In fact, however, the concept of “rebound scurvy” in babies is supported by extremely weak evidence.¹⁵ Since the publication in 1965 of the report upon which this mistaken notion is based, millions of women have consumed high amounts of vitamin C during pregnancy and not a single new case of rebound scurvy has been reported.¹⁶

A preliminary study found that people who took 500 mg per day of vitamin C supplements for one year had a greater increase in wall thickness of the carotid arteries (vessels in the neck that supply blood to the brain) than those who did not take vitamin C.¹⁷ Thickness of carotid artery walls is an indicator of progression of atherosclerosis. Currently, no evidence supports a cause-and-effect relationship for the outcome reported in this study. The vast preponderance of research suggests either a protective or therapeutic effect of vitamin C for heart disease, or no effect at all.

People with the following conditions should consult their doctor before supplementing with vitamin C: glucose-6-phosphate dehydrogenase deficiency, iron overload (hemosiderosis or haemochromatosis), history of kidney stones, or kidney failure.

It has been suggested that people who form calcium oxalate kidney stones should avoid vitamin C supplements, because vitamin C can be converted into oxalate and increase urinary oxalate.¹⁸ ¹⁹ Initially, these concerns were questioned because of potential errors in the laboratory measurement of oxalate.²⁰ ²¹ However, using newer methodology that rules out this problem, recent evidence shows that as little as 1 gram of vitamin C per day can increase the urinary oxalate levels in some people, even those without a history of kidney stones.²² ²³ In one case, 8 grams per day of vitamin C led to dramatic increases in urinary oxalate excretion and kidney stone crystal formation causing bloody urine.²⁴ People with a history of kidney stones should consult a doctor before taking large amounts (1 gram or more per day) of supplemental vitamin C.

Despite possible therapeutic effects of vitamin C in people with diabetes at lower intakes, one case of increased blood sugar levels was reported after taking 4.5 grams per day.²⁵

Are there any drug interactions?
Certain medicines may interact with vitamin C. Refer to drug interactions for a list of those medicines.

Resources

See a list of books, periodicals, and other resources for this and related topics.

*Athletes and fitness advocates may claim benefits for vitamin C based on their personal or professional experience. These are individual opinions and testimonials that may or may not be supported by controlled clinical studies or published scientific articles on vitamin C. For more complete and detailed information, including references and safety information, see Vitamin C as a nutritional supplement.

References

1. Jakeman P, Maxwell S. Effect of antioxidant vitamin supplementation on muscle function after eccentric exercise. Eur J Appl Physiol 1993;67:426–30.

2. Kaminski M, Boal R. An effect of ascorbic acid on delayed-onset muscle soreness. Pain 1992;50:317–21.

3. Thompson D, Williams C, McGregor SJ, et al. Prolonged vitamin C supplementation and recovery from demanding exercise. Int J Sport Nutr Exerc Metab 2001;11:466–81.

4. Thompson D, Williams C, Garcia-Roves P, et al. Post-exercise vitamin C supplementation and recovery from demanding exercise. Eur J Appl Physiol 2003;89:393–400.

5. Johnston CS, Swan PD, Corte C. Substrate utilization and work efficiency during submaximal exercise in vitamin C depleted-repleted adults. Int J Vitam Nutr Res 1999;69:41–4.

6. Gerster H. The role of vitamin C in athletic performance. J Am Coll Nutr 1989;8:636–43 [review].

7. Tiidus PM, Houston ME. Vitamin E status and response to exercise training. Sports Med 1995;20:12–23 [review].

8. Akova B, Surmen-Gur E, Gur H, et al. Exercise-induced oxidative stress and muscle performance in healthy women: role of vitamin E supplementation and endogenous oestradiol. Eur J Appl Physiol 2001;84:141–7.

9. Simon-Schnass I, Pabst H. Influence of vitamin E on physical performance. Int J Vitam Nutr Res 1988;58:49–54.

10. Shepard RJ. Vitamin E and athletic performance. J Sports Med 1983;23:461–70 [review].

11. Johnston CS. Biomarkers for establishing a tolerable upper intake level for vitamin C. Nutr Rev 1999;57:71–7.

12. Sandstead HH. Copper bioavailability and requirements. Am J Clin Nutr 1982;35:809–14 [review].

13. Finley EB, Cerklewski FL. Influence of ascorbic acid supplementation on copper status in young adult men. Am J Clin Nutr 1983;37:553–6.

14. Wilson JD. Vitamin deficiency and excess. In Fauci AS, Braunwald E, Isselbacher KJ, et al. (eds). Harrison’s Principles of Internal Medicine, 14th ed. New York, McGraw Hill, 1998, 487.

15. Cochrane WA. Overnutrition in prenatal and neonatal life: a problem? Can Med Assoc J 1965;93:893–9.

16. Gaby AR. The myth of rebound scurvy. Townsend Letter for Doctors 2000;June:122.

17. Dwyer J, Nicholson LM, Shircore A, et al. Vitamin C intake and progression of carotid atherosclerosis. The Los Angeles Atherosclerosis Study. American Heart Association Annual Meeting. March 2, 2000 [abstract].

18. Piesse JW. Nutritional factors in calcium containing kidney stones with particular emphasis on vitamin C. Int Clin Nutr Rev 1985;5:110–29 [review].

19. Ringsdorf WM, Cheraskin WM. Medical complications from ascorbic acid: a review and interpretation (part one). J Holistic Med 1984;6:49–63.

20. Hoffer A. Ascorbic acid and kidney stones. Can Med Assoc J 1985;32:320 [letter].

21. Wandzilak TR, D’Andre SD, Davis PA, Williams HE. Effect of high dose vitamin C on urinary oxalate levels. J Urol 1994;151:834–7.

22. Levine M. Vitamin C and optimal health. Presented at the February 25, 1999 60th Annual Biology Colloquium, Oregon State University, Corvallis, Oregon.

23. Levine M, Conry-Cantilena C, Wang Y, et al. Vitamin C pharmacokinetics in healthy volunteers: evidence for a recommended dietary allowance. Proc Natl Acad Sci 1996;93:3704–9.

24. Auer BL, Auer D, Rodgers AL. Relative hyperoxaluria, crystalluria and haematuria after megadose ingestion of vitamin C. Eur J Clin Invest 1998;28:695–700.

25. Branch DR. High-dose vitamin C supplementation increases plasma glucose. Diabetes Care1999;22:1218 [letter].

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Learn more about the authors of Healthnotes.

The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or chemist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires September 2008.

2007-09-01

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