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ZMA: The Supplement Everyone Is Sleeping On?

Kevin Kuhn: Classified Nutrition

It was way back in 2011 that I first heard about “this amazing sleep-recovery” supplement called ZMA.  A quick dig into some “Google” research explained that ZMA is a proprietary blend of two minerals (Zinc and Magnesium) and vitamin B6.  The basic claim I originally heard associated with ZMA supplementation is that ingesting it before bed would make you have weird dreams and then you would wake up feeling really well rested and recovered.  Before I bought a bottle, I wanted to read the research myself, so I did some more thorough reading.  When it comes to research on a specific supplement ingredient, there is usually a pretty obvious trend in the research with regards to “does it work, or not” when you read a handful of studies or a review of literature.  This is generally the case, but not quite so with ZMA.  

I still have yet to see so few studies published on a product that has such a big following.  If that were not strange enough, the studies did not give me a general answer to my question, and in fact, seemed to all contradict each other.  Let me show you what I mean.

The “original” ZMA study, conducted at Western Washington University, and published in 2000, was assisted by Victor Conte and BALCO Labs.  Yes, the same Victor Conte and BALCO Labs that was part of the giant doping scandal less than two years later.  I don’t say this to muddy the water or to make any claims, but to give you some context around this study.  

That being said, this study looked at the effects of nightly ZMA supplementation on anabolic and hormonal responses during spring training for collegiate football athletes.  Over the course of this 8-week, randomized and double-blind, placebo-controlled study, those taking ZMA showed a 30+ percent increase in testosterone levels while the placebo group showed a 10 percent decrease in testosterone.  The ZMA group also experienced a 5 percent increase in IGF-1 while the placebo group dropped by 20 percent.  Those numbers sound amazing, right?  I mean, just take a special combination of zinc, magnesium, and B6 and your hormones do some pretty awesome things.  Important to note is that zinc is a very important mineral related to testosterone production and androgen receptors, which are specific sites that hormones, like testosterone, have to bind to before they can exert their effects.  So, if you have low testosterone levels, you may be zinc deficient.  Back to the data.

ZMA: The Supplement Everyone is Sleeping On?

“If you have low testosterone levels, you may be zinc deficient”

Let’s contrast that study with one conducted and published 4 years later.  The methods used in this study were very closely matched to the previous study.  This also lasted 8 weeks, though instead of collegiate football players during the spring (off-season), this study used resistance trained males and a standardized resistance-training program.  The authors tested body composition using a DEXA-Scan, 1-RM Bench Press and Leg Press, Wingate Anaerobic Power, and blood analysis to measure specific anabolic and catabolic hormone levels.  At the end of the 8 weeks, the results indicated that even though there was a slight, though not significant, increase in serum zinc levels, there were no significant changes in any of the body composition measures, 1-RM tests, upper or lower body endurance, anaerobic power, or markers of anabolic or catabolic hormones.  That is quite the contrast compared to the first study.  So, what other information do we have to draw from?        

Since ZMA contains zinc, and zinc plays a role in testosterone production, a study looking at the direct effects of ZMA on the claims that it increases testosterone was conducted and published in 2009.  It is extremely important to note that all 14 participants in this study were recreationally active and not zinc deficient, and, based on dietary review, consumed at least the recommended daily allowance of zinc.  Each participant consumed the recommended ZMA dose, or placebo, between dinner and bedtime for 8 weeks.  The authors found that even though the ZMA group experienced significant increases in serum zinc levels as well as increases is zinc concentration in urine in comparison to the placebo group, there were no significant changes between groups on total or free testosterone.  A major change was noted that urinary pH and urine flow were both elevated in the ZMA group, and because of this, the authors concluded that ZMA may actually negatively affect hydration levels as well as acid-base homeostasis.  

So based on the data, “does it work, or not?”  It seems we can only speculate as to why ZMA had such amazing effects according to one study, and then no performance or recovery effects, at all, in other studies.  It appears to be certain that if you eat a diet rich in oysters, crab, beef shanks, and pork shoulder, then you probably are not deficient in zinc, and ZMA supplementation will probably confer no recovery benefit.  If you do not each these foods very often, then getting some blood work done to see if you have vitamin and mineral deficiencies can be a game-changer with regards to how you can perform and recover.  Remember, however, that with regard to most vitamin and mineral supplements, they seem to only be beneficial and effective if your diet leaves you nutritionally deficient.  

For many individuals, supplementing with ZMA may provide huge benefits because it provides necessary zinc and magnesium they may not be getting otherwise.  For most people, though, do not expect a 30 percent increase in your testosterone levels.  So always check the label, and compare the claims to published data.  Never forget, “if it sounds too good to be true, it probably is.”                      




Wilborn CD, Kerksick CM, Campbell BI, et al. Effects of Zinc Magnesium Aspartate (ZMA) Supplementation on Training Adaptations and Markers of Anabolism and Catabolism. J Int Soc Sports Nutr. 2004;1(2):12-20.

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;63(1):65-70.

About Kevin Kuhn

Kevin KuhnKevin Kuhn, M.S.Ed., CSCS, MFS is a Kinesiologist and Sport Nutrition Coach in Dallas, Texas, as well as the Vice President of Research and Development for Classified Nutrition (ClassifiedNutrition.com).  Before moving to Dallas in 2012, Kevin was the head strength & conditioning coach for the Indiana Invaders professional running club in Indianapolis, Indiana.  Kevin specializes in athletic performance with great interest and experience in running-specific strength & conditioning, corrective exercise, and exercise and sport nutrition.  Kevin has been certified by the National Strength & Conditioning Association as a Certified Strength and Conditioning Specialist (CSCS) and as a Master Fitness Specialist by the Cooper Institute.

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