Zinc (Zn) is a metal and is called an essential trace element because zinc is necessary for human health in very small amounts. Over 300 enzymes require zinc for their activation and nearly 2000 transcription factors require zinc for gene expression . Zinc, as a supplement, is available in tablet or capsule form and is used to prevent or treat zinc deficiency. It is also used for boosting the immune system, treating the common cold and recurrent ear infections, and preventing lower respiratory infections.
Effects of Zinc Status on Testosterone Levels and Other Growth Related Hormones
Severe and moderate deficiency of zinc is associated with hypogonadism in men . Statistically significant positive correlation was observed between serum zinc and serum testosterone in men  but not women, suggesting that slight zinc deficiency act on testicular level rather than pituitary gonadotropins .
Zinc deficiency reduces circulating luteinizing hormone and testosterone concentrations, alters hepatic steroid metabolism, and modifies sex steroid hormone receptor levels, thereby causing male reproductive dysfunction . Koehler, K., et al.  investigated weather supplementation with zinc-containing ZMA, which is often marketed as testosterone booster, can increase serum testosterone levels. Study was conducted on fourteen healthy, regularly exercising men. No significant changes in serum total and serum free testosterone were observed in response to ZMA use. Except for one highly biased study  all other reported that supplementation of zinc only increases testosterone in pathological conditions linked to a low zinc status [10,11] and elderly men [7,12]. Kilic and colleagues  reported that supplementation of zinc reversed reduced serum testosterone levels caused by exhaustion exercise.
Zinc has also shown as 5-alpha reductase inhibitor , which converts testosterone into dihydrotestosterone (DHT). In animal study , where rats were fed Zinc deficient food, weight gain was reduced by 83% compared with control group. Insulin-like growth factor-1 was reduced by 69%, while insulin was reduced by 66%. Overall, zinc deficient food caused apparent growth inhibition.
Zinc deficiency appears to inhibit some growth related hormones but its excessive use does not increase them above normal levels when sufficient zinc is provided by the regular diet.
Zinc Deficiency: How Likely are You Zinc Deficient?
It is estimated that as much as 25% of the world’s population is at risk of being zinc deficient. Nutritional deficiency of zinc may affect nearly 2 billion subjects in the developing world . However, most physically active individuals consume diets that provide amounts of zinc sufficient to meet population standards. Inadequate intakes of zinc have been reported for participants in activities requiring restriction of body weight .
Experimental evidence indicates that acute physical activity increases loss of minerals but that these losses are lasting only for a short time . No alteration in mineral status as evidenced by plasma or serum concentrations are evident in population whose dietary intake of the mineral elements is consistent with population guidelines .
Other Zinc Benefits
It is believed that Zinc possesses antioxidant properties, which may slow down aging of the skin and muscles of the body. However, studies differ as to its effectiveness . Zinc also helps speed up the healing process after an injury . It is also beneficial to the body’s immune system and its deficiency may have effects on all parts of the human immune system .
Zinc Side Effects and Toxicity
Besides its needed effects, it may also cause some unwanted effects especially when taken in large doses. Side effects with large doses include: chills, continuing ulcers or sores in mouth or throat, fever, heartburn, indigestion, nausea, sore throat, unusual tiredness or weakness . Symptoms of overdose include: chest pain, dizziness, fainting, shortness of breath, vomiting, yellow eyes or skin .
Taking 450 mg or more of zinc daily can cause problems with blood iron. Single doses of 10-30 grams of zinc can be fatal.
(Other common names: Zinc Acetate, Zinc Acexamate, Zinc Aspartate, Zinc Chloride, Zinc Citrate, Zinc Difumarate Hydrate, Zinc Gluconate, Zinc Methionine, Zinc Monomethionine, Zinc Murakab, Zinc Orotate, Zinc Oxide, Zinc Picolinate, Zinc Pyrithione, Zinc Sulfate, Zinc Sulphate, Zincum Aceticum, Zincum Gluconicum, Zincum Metallicum, Zincum Valerianicum, Zn, Atomic Number 30)
(Commonly used brand names: Prostavan, Galzin, M2 Zinc 50, Orazinc 110, Orazinc 220, Zinc-220, Zinc Chelated, Zn Plus Protein)
- Milbury, Paul E.; Richer, Alice C. (2008). Understanding the Antioxidant Controversy: Scrutinizing the “fountain of Youth”. Greenwood Publishing Group. p. 99.
- Keen, Carl L., and M. Eric Gershwin. “Zinc deficiency and immune function.” Annual review of nutrition 10.1 (1990): 415-431.
- Om AS, Chung KW. Dietary zinc deficiency alters 5 alpha-reduction and aromatization of testosterone and androgen and estrogen receptors in rat liver. J Nutr. (1996)
- Stamatiadis, D., Marie‐Claire Bulteau‐Portois, and Irene Mowszowicz. “Inhibition of 5α‐reductase activity in human skin by zinc and azelaic acid.” British Journal of Dermatology 119.5 (1988): 627-632.
Dørup, Inge, et al. “Role of insulin-like growth factor-1 and growth hormone in growth inhibition induced by magnesium and zinc deficiencies.” British Journal of Nutrition 66.03 (1991): 505-521.
- Koehler, K., et al. “Serum testosterone and urinary excretion of steroid hormone metabolites after administration of a high-dose zinc supplement.” European journal of clinical nutrition 63.1 (2007): 65-70.
Prasad, Ananda S., et al. “Zinc status and serum testosterone levels of healthy adults.” Nutrition 12.5 (1996): 344-348.
Hartoma, R. “Serum testosterone compared with serum zinc in man.” Acta Physiologica Scandinavica 101.3 (1977): 336-341.
Brilla, L. R., and Victor Conte. “Effects of a novel zinc-magnesium formulation on hormones and strength.” J Exerc Physiol Online 3.4 (2000): 26-36.
Netter, A., K. Nahoul, and R. Hartoma. “Effect of zinc administration on plasma testosterone, dihydrotestosterone, and sperm count.” Systems Biology in Reproductive Medicine 7.1 (1981): 69-73.
Favier, Alain Emile. “The role of zinc in reproduction.” Biological trace element research 32.1-3 (1992): 363-382.
Haboubi, N. Y., et al. “Zinc supplementation and erythropoiesis in the elderly.” Journal of clinical pathology 41.6 (1988): 706.
Kilic, Mehmet, et al. “The effect of exhaustion exercise on thyroid hormones and testosterone levels of elite athletes receiving oral zinc.” Neuro endocrinology letters 27.1-2 (2005): 247-252.
Ali, Hasan, et al. “Relationship of serum and seminal plasma zinc levels and serum testosterone in oligospermic and azoospermic infertile men.” Journal of the College of Physicians and Surgeons–Pakistan: JCPSP 15.11 (2005): 671-673.
Prasad, Ananda S. “Discovery of human zinc deficiency: 50 years later.” Journal of Trace Elements in Medicine and Biology 26.2 (2012): 66-69.
Lukaski, Henry C. “Magnesium, zinc, and chromium nutriture and physical activity.” The American journal of clinical nutrition 72.2 (2000): 585s-593s.
Zinc supplement (Oral route, Parenteral route) – Drugs.com Retrieved 28.7.2015