The mineral zinc plays a strong role in male reproductive health. Even a mild zinc deficiency has been associated with decreased testosterone levels in men, low sperm concentrations in semen and a reduction in lean body mass. Research on male subjects has also shown that increasing zinc intake can reverse these negative effects.
Zinc's Role in Reproductive Health
Zinc plays many roles in the human body, including a role in reproduction. This is largely because zinc aids in testosterone synthesis. In men, the testes require zinc to function properly. Severe zinc deficiency compromises a male's ability to produce sperm, and this, in turn, could compromise overall fertility. A 2011 mouse study published in the "Journal of Nutrition" found a reduced zinc diet was associated with fertility problems independent of circulating zinc or testosterone levels.
Low Zinc, Low Testosterone
For decades, scientists have been establishing a correlation between low testosterone and zinc deficiency. A 1992 study involving 11 volunteers found that even short-term zinc depletion could lower testosterone levels in young men. More recent research -- a 2011 study published in the journal "Biological Trace Element Research" -- found men with normal testosterone levels had significantly higher zinc levels than did men with low testosterone. And men with lower levels of zinc are more likely to have lower testosterone levels, according to a 2012 study of 25- to 55-year-old men that was published in the "African Journal of Medicine and Medical Sciences."
Zinc Supplements and Testosterone
A study published in the "Nigerian Journal of Physiological Science" in 2013 found that rats given zinc supplements for six weeks showed significantly increased testosterone levels compared to rats who didn't get zinc supplements. Animals who took the zinc also had improved sperm quality. In a human study, researchers from Wayne State University looked at the relationship between zinc levels and testosterone in healthy men ages 20 to 80. After 20 weeks of zinc restriction, young men showed a significant decrease in testosterone concentration, while older men who took zinc supplements during this time boosted their testosterone levels. The research was published in the journal "Nutrition."
The U.S. National Research Council recommends 15 milligrams of zinc daily for adult men and women. Zinc deficiency can lead to immune system problems, decreased lean body mass and lower testosterone levels. Stunted growth and cognitive impairment could also result from zinc deficiency. Severe zinc deficiency could lead to alopecia (hair loss), diarrhea, emotional disorders, weight loss, infections, hypogonadism in males and problems with ulcer healing.