What is ZMA?
ZMA is a supplement stack consisting of Zinc Monomethionine, Magnesium Aspartate, and often Vitamin B6, or Pyroxidine. It is claimed to increase strength and boost testosterone levels, and is used as a sleep aid.
Where does ZMA come from?
ZMA was formulated by Victor Conte, the founder of infamous supplement manufacturer BALCO, and now head of SNAC nutrition. While the ZMA formula is not patented, the name ZMA is a trade mark. Many supplement manufacturers purchase ZMA from SNAC and include it in their formulations, while other supplements, perfectly legally, include the same or similar ingredients and sell these under a different name to avoid breaching SNAC's trademark.
ZMA Health Benefits
The components in ZMA – Zinc, Magnesium, Aspartate and B6 – all have health benefits individually. Zinc is an essential trace element with a role in maintaining the health of the immune system, and it is also necessary for the functioning of over 100 different enzymes. Magnesium is also classified as an essential trace element, is required for healthy bones and teeth, and participates in a huge number of chemical reactions in the body. Aspartate is an amino acid which enhances the absorption of zinc and magnesium, and B6 is important in amino acid and glucose metabolism.
ZMA Benefits for Bodybuilding
ZMA is marketed as a testosterone booster, strength enhancer, and sleep aid.
Zinc deficiency, even at marginal levels, can cause hypogonadism, and a drop in testosterone levels. Zinc is excreted through the urine after exercise and deficiency is prevalent throughout the world. It has been shown that Zinc supplementation can reverse this, and correcting a deficiency can cause testosterone levels to rise (1). Zinc also has antioxidant properties that can protect the muscles from damage.
There is evidence that low magnesium levels are connected to insulin resistance, and supplementation may result in better utilisation of glucose by the body if these levels are low (2). Studies in athletes have shown an increase in strength with magnesium supplementation (3) and raised testosterone levels (4). It is known that B6 plays a role in the metabolism of dietary protein. Without sufficient B6, the body can be inefficient in utilising nitrogen and performing many reactions involving conversions of amino acids. B6 affects the conversion of tryptophan to serotonin and melatonin, which can promote healthy sleep. B6 also promotes absorption of the other two ingredients.
ZMA Side Effects, Safety and Negatives
While the benefits of the individual components of ZMA are established in the case of deficiency, the research around the ZMA stack is controversial. There has been one study undertaken in football players that showed ZMA increased strength, IGF-1 and testosterone levels, however this research has been criticised as it was co-authored by Conte, the owner of the ZMA patent, and funded by SNAC Nutrition, the manufacturer (5). Subsequent studies have not shown that ZMA has any effect on strength or testosterone in healthy males (6,7). The amount of research on ZMA is small, but many people report great results with this supplement in spite of conflicting scientific evidence.
ZMA is generally regarded as a safe supplement, but mild side effects like stomach irritation and diarrhoea have been reported in some people, particularly where higher doses of magnesium are included. It also has the potential to cause drowsiness, and some people report increased acne.
Zinc competes with copper for absorption in the body. Long term or high dose zinc supplementation can cause copper deficiencies, and many zinc supplements actually contain small amounts of copper to offset this potential issue.
Vitamin B6, particularly when taken before bed, has been reported to induce very vivid dreams, although some may see this as a positive.
ZMA recommended dosage and timing
Th best time to take ZMA is an hour before bed, as it is used to promote sleep and it can cause drowsiness. It is best to take it on an empty stomach. The dosages in SNAC's proprietary formula are 30mg zinc, 450mg magnesium aspartate, and 10.5mg of vitamin B6 per dose.
Because ZMA promotes sleep and testosterone production, it is other found stacked with similar ingredients. It is important not to stack ZMA with anything containing calcium, like whey or casein, as the calcium will impede the absorption of magnesium and zinc.
(1) Prasad AS, Mantzoros CS, Beck FW, Hess JW, Brewer GJ. Zinc status and serum testosterone levels of healthy adults. Nutrition.1996 May;12(5):344-8.
(2) G. Paolisso, A. Scheen, F. D'Onofrio, P. Lefèbvre (1990), 'Magnesium and glucose homeostasis', inDiabetologia, 33: 511-514
(3) Brilla LR, Haley TF. Effect of magnesium supplementation on strength training in humans. J Am Coll Nutr. 1992;11(3):326-329.
(4) Cinar V, Polat Y, Baltaci AK, et al. Effects of magnesium supplementation on testosterone levels of athletes and sedentary subjects at rest and after exhaustion. Biol Trace Elem Res. 2011;140:18–23.
(5) Brilla LR, Conte V. Effects of a novel zinc-magnesium formulation on hormones and strength. JEPOnline. 2000;3(4):26-36.
(6) Wilborn CD, Kerksick CM, Campbell BI, Taylor LW, Marcello BM, Rasmussen CJ, Greenwood MC, Almada A, Kreider RB. Effects of Zinc Magnesium Aspartate (ZMA) Supplementation on Training Adaptations and Markers of Anabolism and Catabolism. J Int Soc Sports Nutr. 2004 Dec 31;1(2):12-20.
(7) Koehler K, Parr MK, Geyer H, Mester J, Schänzer W. Serum testosterone and urinary excretion of steroid hormone metabolites after administration of a high-dose zinc supplement. Eur J Clin Nutr. 2009 Jan;63(1):65-70