This week’s supplement of the week is Zinc Magnesium Aspartate, better known as ZMA. Read any bottle of ZMA or any description from a maker of ZMA and there will be strong claims that it aids in increasing testosterone, muscle recovery and promoting more restful sleep. Obviously these would all be great for anyone looking to build muscle, but are the claims true?

ZMA is a specifically formulated ratio of 30 mg zinc, 450 mg magnesium and 10.5 mg vitamin B-6 which is supposed to help maximize the effectiveness of the minerals involved. The basis behind the effectiveness of ZMA is that strenuous training can result in a loss of the body’s zinc and magnesium levels and you need to replace them because of this.

Most of ZMA’s claims are based on a study done by Brilla and Conte (1999) which took off-season football players and had them train and supplement with ZMA and showed subjects had an increase in testosterone, IGF-1 and muscle strength. (1) There is also evidence that when subjects have a zinc deficiency supplementing with ZMA can help increase zinc levels. (2)

That all sounds great, but I think it lacks credibility. For one the study with the football players was financed by one of the researchers and holds the patent on the product being tested. Not that if something is financed by a researcher or a company it can’t be credible, but in my opinion it at least needs to be a peer-reviewed journal. Sometimes companies will fund a study to prove their product works, and getting peer-reviewed journals published is very difficult.

Further research on the subject of ZMA does not appear to coincide with Brilla and Conte. While a 2004 study by Wilborn et al. published in the Journal of the International Society of Sport Nutrition did show there was a non-significant 12-17% increase in serum zinc levels in subjects taking ZMA with training (magnesium was not affected) it did not in turn find it had any effect on anabolic hormones, strength or lean body mass. This study also found that zinc and magnesium levels were not negatively impacted by training. (3) In support of this Lukasi (1995) showed that while some research does suggest zinc and magnesium levels are diminished in athletes, most of them get adequate intake of both minerals through dietary intake making supplementation unnecessary. (4)

Now as for sleep, this one amazes me. With so many strong claims of ZMA helping support sleep patterns, I found absolutely no research whatsoever supporting this claim when using ZMA directly. Not only could I not find any research to support it, I couldn’t even find any research that even looked at it. The only things out there I could find that could support this at all was research by Hornyak et al. (1998) that showed subjects with insomnia significantly improved their symptoms with oral magnesium therapy. (5) The other being research by Tanabe at al. (1998) which showed chronic sleep deprivation causes magnesium deficiency as well as decreased exercise tolerance (big surprise there) and that the decreased exercise tolerance resulting from the sleep deprivation could be improved with oral magnesium administration. (6)

My take away from the sleep claims is that if you are deficient in magnesium or have chronic sleep deprivation ZMA might, and I stress the word might, be of some use, but I haven’t seen any research strong enough to convince me it definitely helps those who train frequently. As for claims of increasing testosterone and muscle anabolism, I’m definitely not convinced.

Much like glutamine ZMA is relatively inexpensive, but I personally believe you are once again better off spending your money elsewhere. It’s possible there are some benefits to sleep but there needs to be more research done on the supplement to get a better understanding.

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This article was researched and written by Colin DeWaay

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