Zinc is an essential mineral found in some foods, available as a dietary supplement and added to cold remedies like lozenges because of its immune boosting effects. (Learn about more foods that boost the immune system.)
But what can zinc supplements do for athletes looking to improve their performance?
A 2011 study showed that zinc supplementation had a positive hormonal benefit following exercise. The researchers broke participants into four groups. Those who took a zinc supplement had higher serum testosterone levels following exercise than those who didn't. This is critical for muscle growth and recovery.
In a 2006 study conducted in Turkey, 10 wrestlers who took daily doses of 3 mg zinc sulfate per kilogram of body weight averaged a 40% increase in free testosterone levels in their blood after four weeks.
The benefits of zinc supplementation go beyond testosterone. Zinc has been linked to improved immune function, and as an antioxidant and anti-inflammatory, all of which can benefit hard-training athletes. A study published in Molecular Nutrition & Food Research correlates age-related zinc deficiency with immune system dysfunction and chronic inflammation during the aging process. The strain an athlete puts on his body practicing and competing on a daily basis can lead to this deficiency, regardless of his or her age, if the zinc shortfall is not made up through diet and/or supplementation.
Before you self diagnose and start supplementing at will, determine if you're deficient by getting a serum blood test of your zinc levels. The reference range is 10.7 - 22.9µmol/L (70-150 µg/dl). If you want to get a general sense of your levels at home, dilute a small amount of zinc sulphate in water, drink a tablespoon of it and hold it in your mouth for 10 seconds. You should experience an immediate "metallic" taste sensation. If the solution tastes like plain water, this can indicate a deficiency. For more accurate results, don't eat or drink for at least an hour before the test.
How Much to Take?
Excessive intake can result in zinc toxicity, so before you start popping zinc tablets at random, get a baseline test through one of the above methods and adhere to the U. S. Food & Drug Administration's daily recommended intake of 15 milligrams. A 2010 study showed zinc overload can lead to oxidative stress, copper imbalance and weakened immune function, so too much can do more harm than good.
Like anything else, think "moderation." Focus first on adding natural sources of zinc to your diet. Look to zinc supplements only if you find your dietary intake is insufficient.
Zinc Food Sources
- Oysters - According to Healthaliciousness.com, this seafood is the richest source of zinc, with as much as 182mg per 100g serving.
- Wheat Germ - In addition to its high amounts of selenium and magnesium, wheat germ also packs a nutritional punch of zinc (as much as 17mg per 100g serving). Sprinkle it on salads or yogurt, or add it to smoothies and reap the benefits.
- Beef - Roast or ground beef yields about 10mg of zinc per 100g serving.
- Dark Chocolate - Unsweetened baking chocolate provides 9.6mg of zinc per 100g serving (most bars are 50-100 grams).
- Peanuts - Dry roasted peanuts provide 3.3mg per 100 gram serving, or 4.8mg per cup. Learn about some of the best peanut butter snacks for athletes.
As you can see, unless you have a significant deficiency to begin with, meeting your recommended daily zinc intake through dietary sources is quite possible.
 Neek, L. et al. Effect of Zinc and Selenium Supplementation on Serum Testosterone and Plasma Lactate in Cyclist After an Exhaustive Exercise Bout. Biological Trace Element Research. 9 July 2011.
 Kilic, M. et all, The effect of exhaustion exercise on thyroid hormones and testosterone levels of elite athletes receiving oral zinc . Neuro Endocrinol Lett. 2006 Feb-Apr; 27(1-2):247-52.
 Wong, C., Ho, E. Zinc and its Role in Age-Related Inflammation and Immune Dysfunction . Molecular Nutrition and Food Research. 2012. 56, 77-87
 Plum, L., Lothar, R., and Haase, H. The Essential Toxin: Impact of Zinc on Human Health . Int J Environ Res Public Health. 2010 April; 7(4): 1342-1365