Vitamin A

How You May Benefit:

Boost immune functioning
Stimulate the immune system and fight infection
Fight free radicals
Fight free-radical/oxidative damage
Improve sensory abilities
Support healthy vision, especially effective against night blindness

Overview

This fat-soluble vitamin plays a vital role in the maintenance of optimal vision and a strong immune system, especially in fighting viral attacks. It has antioxidant abilities, has been used to treat skin conditions, and has shown anti-carcinogenic characteristics.

Usage

Amount: Supplement levels from 5,000 to 7,000 IU's is the range generally recognized to satisfy health-maintenance needs for healthy adults. Optimal antioxidant benefits require an increased amount—from 20,000 to 30,000 IU will generally turn the switch. At this level, beta-carotene is the better form to use.

The need for Vitamin A may be increased by stressful conditions such as an illness, infection, emotional trauma, long-term anxiety, chronic alcohol use, or smoking. Requirements depend on bodyweight, so consider adjusting according to what your scale reads.

Daily levels of 10,000 IU are generally well tolerated, but in the absence of deficiencies, amounts above 50,000 IU can be toxic when taken for extended periods of time.

Timing: As Vitamin A is stored in fat, it is not essential to take it every day, but when you do supplement, do so with food—it helps absorption.

This essential nutrient is important for an athlete's overall health—of particular concern is its effects on a healthy immune system, vital to athletes under stress. And of course, its impact on vision can't be overlooked.

Vitamin A supplementation may become a higher priority for athletes on a low- to moderate-fat diet, commonly used to reduce bodyfat levels—because the richest sources of this vitamin are in high-fat foods.

Safety Information

Safety:
Pregnant women should consume less than 10,000 IU's per day to avoid the risk of birth defects.

Toxicity:
Toxicity is often described when 50,000 to 100,000 IU's are supplemented over an extended amount of time. If toxic levels are reached, swelling of the brain causing headache, nausea, vomiting, irritability, dizziness, abdominal pain, hair loss, weight loss, menstrual problems, and stunted growth may be experienced.

Bans and Restrictions:
None reported.

References

Bendich, A., and Langseth, L., "Safety of Vitamin A," Am J Clin Nutr 49.2 (1989) : 358-71.

Haas, E.M., Staying Healthy with Nutrition (Celestial Arts, Berkeley, CA, 1992) : 84, 94-8.

Mastroiacovo, P., et al., "High Vitamin A Intake in Early Pregnancy and Major Malformations: A Multicenter Prospective Controlled Study," Teratology 59.1 (1999) : 7-11.

Murray, M.T., Encyclopedia of Nutritional Supplements (Prima Health, Rocklin, CA, 1996) : 19-38.

Ross, A.C., and Ternus, M.E., "Vitamin A as a Hormone: Recent Advances in Understanding the Actions of Retinol, Retinoic Acid, and Beta Carotene," J Am Diet Assoc 93.11 (1993) : 1285-90.

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