ZMA is a scientifically designed anabolic vitamin and mineral formula. It specifically contains Zinc Monomethionine Aspartate, Magnesium Aspartate, and vitamin B-6. It is an all-natural product that has been theorized to significantly increase anabolic hormone levels and muscular strength in trained athletes. In fact, ZMA is thought to be one of the only natural and completely safe methods of supplementation to significantly increase testosterone and growth hormones. ZMA has also been known to increase muscle mass, strength, power, and even enhances sleep quality. However, there have been relatively few studies performed on ZMA since its inception into the supplement industry.
The most talked about and significant study on ZMA is the following by Brilla et al (23) at Washington University. This study reported that ZMA significantly increased free testosterone levels and muscle strength in NCAA football players. Specifically, Brilla reported that a group of competitive NCAA football players who took ZMA nightly during an eight-week spring training program had 2.5 times greater muscle strength gains than a placebo group. In practical terms, this means that if the placebo group improved by only 20 pounds, the ZMA group would improve by 50 pounds. Overall, the strength of the ZMA group increased by 11.6% compared to only a 4.6% increase in the placebo group.
Brilla (23) went on to further say, "The muscle strength increases may have been mediated by the anabolic hormone increases in the ZMA group. The ZMA group had 30% increases in free and total testosterone levels compared to 10 percent decreases in the placebo group. The ZMA group also had a slight increase in insulin-like growth factor-1 (IGF-1) levels compared to a 20 percent decrease in the placebo group. This study shows that anabolic hormone and muscle strength increases can be induced in already strength-trained athletes by using a novel zinc-magnesium preparation." Although it has been debated as to how certain hormonal changes take place such as IGF-1, it appears there are specific mechanisms in ZMA that may trigger physiological changes associated with elevating hormonal responses.
Another benefit commonly associated with ZMA is better sleep (24). Typically, ZMA should be taken 30 - 60 minutes before bed. Although not clinically proven, it has been noted that most people supplementing with ZMA noticed better sleep patterns and a deeper sleep which may directly and indirectly affect athletic performance.
While zinc and magnesium deficiencies are common in the general population, deficiencies of these minerals are even more prevalent in athletes. Research shows that intense exercise and stress related physical activity results in relatively high levels of bodily losses of zinc and magnesium. Furthermore, in 1998, BALCO Laboratories tested the mineral status of over 250 NFL players, including the entire Denver Broncos Super Bowl championship team, as well as the entire Miami Dolphins team. The results showed that over 70% of the football players were either depleted or deficient in both zinc and magnesium (25).
The dosage and proportion is very important. A common multi-vitamin will not produce these results. Most successful ZMA products have: Vitamin B6: 11mg, Magnesium: 450mg, Zinc: 30mg. This product is all-natural and there are no known side effects. It is safe for men and women. Because of the limited studies done on this supplement, much more research is needed to clarify all based conclusions in regards to ZMA.
Summary and Recommendation
There is currently very little research and evidence found for ZMA supplementation. Although the supplement receives critical acclaim from the bodybuilding industry and many athletes, there lacks sufficient scientific studies to fully condone ZMA supplementation. The few studies that have been performed on ZMA, such as those previously described, have favorable conclusions and results that support ZMA. It appears ZMA increases strength, growth hormone levels, testosterone, muscle mass, IGF-1 levels, and enhanced sleep patterns.
Dosage recommendations for ZMA seem to be very inconclusive. In fact, consumerlab.com does not have any recommendations in regards to ZMA. However, most successful ZMA products have: Vitamin B6: 11mg, Magnesium: 450mg Zinc: 30mg. It appears that the ratio of the three substances found in ZMA is very critical for its maximum potency. It is typically recommended that ZMA is taken before sleep on an empty stomach in the same dosage recommendations as stated above. However, certain companies encourage double to triple that dosage as long as the ratio is kept constant. Whether this is an advertising ploy by the companies to sell more of the product or simply a positive performance enhancement, formula has yet to be determined by proper scientific studies. It is currently believed that there is no toxicity associated with ZMA, however, very little research in this specific area is available.
According to consumerlab.com and other valid sources, some of the best ZMA products are manufactured by the following companies: Beverly, Optimum Nutrition, PrimaForce, Dymatize, ISS, Prolab, Ultimate Nutrition, Twinlab, and Universal.
23. Brilla, L. Effects of zinc-magnesium (ZMA) supplementation on muscle attributes of football players. ACSM journal, Medicine and Science in Sports and Exercise, Vol.31, No. 5, May 1999.
24. Bodybuilding.com. ZMA Info and Products. 2006.
25. Conte, V. The Natural Alternative to Prohormones. Fitness Matters- maxmuscle.com. 2006.