ZMA (Zinc monomethionine and aspartate and Magnesium Aspartate) is a supplement used primarily by athletes, gymnasts, and bodybuilders. It is most often used as a recovery aid; most notably, studies show that ZMA helps the body achieve deeper levels of REM sleep. It was developed by Victor Conte (founder of BALCO Laboratories in Burlingame, California) and is a combination of zinc, magnesium and vitamin B6. ZMA claims to raise strength levels and may enhance hormonal profiles. The study most often used to support the hormone effects of ZMA is one done at Western Washington University. Dr. Lorrie Brilla (and a ZMA supplement manufacturer) studied 12 NCAA division II football players who took ZMA nightly during an eight-week spring training program and a separate group assigned a placebo pill. The athletes taking the ZMA had 2.5 times greater muscle strength gains than the placebo group; the ZMA group increased by 11.6 percent compared to only 4.6 percent in the placebo group. The ZMA group also had 30 percent increases in testosterone levels (compared to 10 percent in the placebo group)
The original ZMA formula is composed of zinc monomethionine and aspartate (30 mg), magnesium aspartate (450 mg), and vitamin B6 as pyridoxine hydrochloride (10.5 mg). According to the label directions, ZMA should be taken 30 - 60 minutes prior to bedtime and on an empty stomach to help synchronise absorption with sleep. Also, the product should not be taken with foods or supplements containing calcium because calcium blocks the absorption of zinc.
Since ZMA is a registered trademark of SNAC Nutrition (SNAC Systems Inc.) but not a patented formula, other manufacturers using the abbreviation for their products may introduce various formulae with different chelated or other compounds (such as citrate, gluconate, and oxide) of basic components (i.e. zinc, magnesium, and vitamin B6), additional ingredients (such as copper, melatonin, fenugreek, Tribulus terrestris, Suma root, and Mucuna pruriens) with properties that are supposedly synergistic with the basic components. Nevertheless, some manufacturers market products of a similar basic formula but do not use the trademark ZMA abbreviation. Furthermore, SNAC Nutrition itself has ZMA-5 (ZMA formula with 5-Hydroxytryptophan) marketed as a sleep enhancer and ZMA Nightcap (ZMA-based proprietary blend with 5-hydroxytryptophan) marketed as an anabolic mineral support.
All three basic components in ZMA formulae are important in biological processes, and while studies have shown that most Americans get enough zinc and vitamin B6, more than 50% don't meet the U.S. government's recommendation for magnesium.
A 1998 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 claimed greater increases in muscle strength. This study was funded by SNAC Systems Inc, the intellectual property right holder, and one of the study's authors, Victor Conte, has ownership 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.
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. The result showed an increase in zinc secretions in urine making it much darker like blood, but no effect on the level of testosterone in the body.
- "Ohio State University Extension Fact Sheet". Retrieved 2006-08-11.
- "More than half of Americans don’t get nearly enough magnesium" (PDF). Retrieved 2006-08-11.
- Wilborn, Colin D; Kerksick, Chad M; Campbell, Bill I; Taylor, Lem W; Marcello, Brandon M; Rasmussen, Christopher J; Greenwood, Mike C; Almada, Anthony; Kreider, Richard B (2004). "Effects of Zinc Magnesium Aspartate (ZMA) Supplementation on Training Adaptations and Markers of Anabolism and Catabolism". Journal of the International Society of Sports Nutrition 1 (2): 12–20. doi:10.1186/1550-2783-1-2-12. PMC 2129161. PMID 18500945.
- Koehler, K; Parr, M K; Geyer, H; Mester, J; Schänzer, W (2007). "Serum testosterone and urinary excretion of steroid hormone metabolites after administration of a high-dose zinc supplement". European Journal of Clinical Nutrition 63 (1): 65–70. doi:10.1038/sj.ejcn.1602899. PMID 17882141.