What is ZMA?
ZMA (Zinc l-monomethionine aspartate, or Zinc Magnesium Aspartate) is a popular supplement amongst athletes (endurance and strength athletes) and bodybuilders. ZMA is promoted as a supplement that may increase levels of zinc and magnesium, natural anabolic hormones (IGF-1 and free testosterone), strength adaptations to training and may guard against depletion of zinc and magnesium during intense training. It consists of a special blend of ingredients that are required for vital biochemical processes: Zinc 30mg (as l-monmethionine and aspartate), Magnesium 450mg (as magnesium aspartate), and Vitamin B6 11mg (as pyridoxine HCL).
Zinc and Magnesium are essential elements that play vital roles in a range of important biochemical processes. Zinc is important for the activity of a large number of enzymes affecting a range of biochemical processes including cell replication, exercise metabolism and antioxidant activity. Magnesium also plays an important role in many biological processes including metabolism and is required for the normal functioning of nerves, muscles, the immune system, and hormones.
Since both magnesium and zinc play key roles in a range of biochemical processes, and prolonged or intense training may lead to deficiencies and negatively affect exercise performance (Córdova and Navas 1998), researchers looked at whether supplementation may help to preserve zinc and magnesium levels and possibly have an ergogenic effect.
Researchers have reported that zinc supplementation may be beneficial for increasing serum testosterone levels in mildly zinc deficient men (Prasad et al., 1996) and magnesium may be of benefit for strength training (Brilla and Hayley 1992). The potential ergogenic effects of zinc and magnesium led to the formulation of ZMA which combined zinc, magnesium and the vitamin B6. Initial research was promising with researchers reporting that ZMA supplementation significantly increased levels of free and total testosterone levels, the levels of IGF-1 (insulin growth factor), and strength gains in a group of resistance training off-season footballers (Brilla and Conte 2000). This research led to the mass promotion of ZMA within the sports supplement industry.
Unfortunately a later study failed to replicate these results and found that despite the ZMA supplement increasing serum zinc levels by a small but non-significant amount (12-17%) it had no significant effect on levels of total or free testosterone, growth hormones, IGF-1, or cortisol (Wilborn et al., 2004). The researchers also failed to observe any increases in 1-repetition maximum strength, anaerobic sprint capacity or muscle endurance. There was also no change in bodymass although they noted favourable trends in fat free mass and body fat. The researchers concluded that ZMA did significantly increase zinc or magnesium status or positively affect the training adaptations of experienced strength trained men with a normal zinc status.
Therefore based on the current research there is insufficient evidence to support the use of ZMA as a sports supplement.
ZMA supplementation may lead to small non-significant increases in serum zinc levels and may have favourable effects on fat free mass. However zma did not appear to be of benefit for increased muscle strength, endurance, anaerobic power, or anabolic hormone levels.
ZMA side effects
ZMA appears to be safe and free of side effects. However, if you are already taking a multivitamin containing zinc you should be aware that excessive zinc consumption may increase levels of LDL-cholesterol – the bad cholesterol implicated in the build-up of cholesterol on artery walls – and can lead to a copper deficiency. Excessive zinc consumption can interfere with the absorption of copper which plays an important role in immune function, white blood cell function, red blood cell production, collagen synthesis, bone health and a healthy nervous system.
How to take ZMA?
The general recommendation is to take ZMA approximately 30-60minutes before bedtime on an empty stomach.
Brilla LR, and Conte V (2000) Effects of a novel zinc-magnesium formulation on hormones and strength. J Exerc Physiol Online 2000, 3:26-36.
Brilla LR, and Haley TF (1992) Effect of magnesium supplementation on strength training in humans.J Am Coll Nutr 1992, 11:326-329.
Córdova A, and Navas FJ. (1998) Effect of training on zinc metabolism: changes in serum and sweat zinc concentrations in sportsmen. Ann Nutr Metab. 1998;42(5):274-82.
Prasad AS, Mantzoros CS, Beck FW, Hess JW, and Brewer GJ (1996) Zinc status and serum testosterone levels of healthy adults. Nutr 1996, 12:344-8.
Wilborn CD, Kerksick CM, Campbell BI, Taylor LW, Marcello BM, Rasmussen CJ, Greenwood MC, Almada A, Kreider RB. (2004) 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. doi: 10.1186/1550-2783-1-2-12.