ZMA (Zinc monomethionine aspartate and Magnesium Aspartate) is a supplement used by bodybuilders and athletes. It was developed by Victor Conte (founder of BALCO Laboratories in Burlingame, California) and is a combination of zinc, magnesium and vitamin B6. The formula is “patent pending” and the name “ZMA” trademarked by SNAC System Inc, also founded by Victor Conte. ZMA is claimed to raise strength levels, but studies don’t show consistent results.

ZMA is a combination of two minerals, zinc and magnesium, and Vitamin B-6 or pyridoxine. All three of these compounds are important in biological processes, and while studies have shown that most Americans get enough zinc and Vitamin B6,[1] more than 50% don’t meet the U.S. government’s recommendation for magnesium.[2]

An increase in exercise can lead to the loss of vitamins and minerals making it particularly important for bodybuilding due to the blood sugar level rises and urination increases, increasing the loss of magnesium, zinc, B12, B6, folic acid, and many other nutrients. Although drinking water re-hydrates an athlete, fruit juice, sports drinks or foods high in water such as vegetables are needed to replenish water-soluble nutrients.

The proportion of ingredients generally used in products is 20-30 mg zinc, 400-500 mg magnesium and ~10mg B6. According to the label directions, ZMA should be taken before bed on an empty stomach (2 hours after eating your last meal and at least 30 minutes prior to any other supplements). The product should not be taken with calcium (cheese,milk,etc.), the reason being that calcium blocks the absorption of zinc.

Scientific studies

A 1999 study was undertaken on NCAA Football players during an 8 week spring training program. The control group was told to cease taking any nutritional supplements. Those who took the ZMA tablets showed greater increases in muscle strength. This study was funded by SNAC Systems Inc. (the patent holders) and one of the study’s authors (Victor Conte) has equity in this company.

In 2004, a study funded by a research grant from Cytodyne (another supplement producing company) with 42 resistance trained males showed that ZMA supplementation had no significant effects on total and free testosterone, IGF-1, growth hormone, cortisol, the ratio of cortisol to testosterone, or muscle and liver enzymes in response to training. No significant effects were observed in changes in strength, upper or lower body muscle endurance, or anaerobic sprint capacity [3].

In another study done in 2006, a team of German scientists conducted a study on the effect of ZMA and testosterone levels in the body[4]. The result showed an increase in zinc secretions in urine, but no effect on the level of testosterone in the body.