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.
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 antioxidant, 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 several 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 diarrhea 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., hemochromatosis, hemosiderosis). Vitamin
C helps recycle the antioxidant, 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 infant with a higher-than-normal requirement for the vitamin. The concern is that the
infant 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 infants
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 hemochromatosis), 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.
*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].