Zinc monomethionine aspartate and magnesium aspartate (commonly known as ZMA) is a supplement that affects the body's hormonal balance. It's generally composed of a large amount of magnesium aspartate, a relatively smaller amount of zinc monomethionine aspartate, and vitamin B6.
Because it's so effective in helping its users sleep better and more deeply, we've added it to our Top 10 Sleep Supplements list on our blog! (Link opens in a new tab)
What it's used for
ZMA is marketed to (and almost exclusively used by) bodybuilders and athletes as a recovery aid. It's believed to improve the quality of sleep and increase muscle gains when taken within an hour of going to bed.
The theory behind ZMA's enhancement of muscle gains is that it promotes the production of testosterone and IGF-1 (an insulin analogue that plays a role in tissue growth).
The core of ZMA's marketing claims is based on a 1998 study of NCAA football players that showed a very significant increase in muscle gains after 8 weeks of supplementation. It should be noted that this particular study was funded by the patent holders of ZMA, SNAC Systems. The co-author of the study, Victor Conte, was also a part owner of SNAC at the time.
The name may sound very familiar, as this is the same Victor Conte that was Barry Bonds' steroid supplier while he was also president of BALCO.
When you pair that information with several other studies that have since found no improvement in muscle gains or performance, and no actual increase in testosterone using ZMA supplementation,[2,3] it's very unlikely that the supplement actually improves workout performance or gains in any significant way. There are studies that have correlated higher zinc levels to elevated testosterone levels,[4,5] but these do not use the specific ZMA supplement, contain differing dosages of zinc, and also have incorporated other minerals (such as selenium).
Claims about ZMA's beneficial effects on sleep are also problematic. They can be roughly broken up into two assertions:
- ZMA helps you fall asleep and combats insomnia.
- During sleep, ZMA promotes growth hormones that aid in muscle recovery from anaerobic exercise.
The first claim seems to largely rely on indirect evidence based on the high magnesium content. Magnesium supplementation has been shown to help combat insomnia, specifically in patients suffering from restless legs syndrome and in the elderly. But it has not been studied in more general populations, and in existing studies, it consisted of magnesium supplementation alone, not the particular ZMA formula.
The second claim ties back into the problems with the claims about muscle gains — it's possible that zinc supplementation alone may elevate natural testosterone production, but there's no evidence whatsoever that ZMA actually increases either testosterone or the production of growth hormones.
ZMA is exclusively sold in tablet form, generally in a 30-day supply per bottle.
The daily ZMA formula it's normally sold at is not known to have any specific side effects. Both the standard dose of zinc (30mg) and magnesium (450mg) in ZMA are slightly in excess of daily nutritional needs for any age or gender, however. Both zinc and magnesium can have side effects in large doses. Nausea is a common side effect of zinc, and magnesium can cause upset stomach and diarrhea.
The main disadvantage of ZMA is simply that there's almost no evidence that it does any of the things it claims to! Both zinc and magnesium do have their valid uses as supplements, but there's nothing to indicate at this point that taking ZMA is any better than supplementing with each of them individually when necessary.
You can find zinc in a variety of foods, most abundantly in meat and seafood. But a good amount is also in a variety of foods like legumes. Magnesium is found in a tremendous range of foods.
Very good sources of zinc
ZMA promotes the production of testosterone and IGF-1, improves the quality of sleep, and increases muscle gains.
- Crab (Alaska king)
- Beef liver
- Beef tenderloin
- Lamb loin
Good sources of zinc
- Sesame and pumpkin seeds
- Green peas
- Crimini mushrooms
Very good sources of magnesium
- Peanuts and peanut butter
- Black beans
A very high intake of magnesium can cause a condition called hypermagnesemia. Symptoms include:
- General weakness
- Nausea and vomiting
- Breathing problems
- Irregular heartbeat
Where to buy
ZMA, as well as individual zinc and magnesium supplements can be found at steep discounts through PricePlow's price comparison engine.
- Brilla, LR, et. al; Journal of Exercise Physiology; "Effects of a Novel Zinc-Magnesium Formulation on Hormones and Strength;" October 2000
- Wilborn, Colin, et. al; Journal of the International Society of Sports Nutrition; "Effects of Zinc Magnesium Aspartate (ZMA) Supplementation on Training Adaptations and Markers of Anabolism and Catabolism;" 2004
- Koehler, K, et. al; European Journal of Clinical Nutrition; "Serum testosterone and urinary excretion of steroid hormone metabolites after administration of a high-dose zinc supplement;" 2009
- Chang, C, et. al; Biological Element Trace Research; "Correlation Between Serum Testosterone Level and Concentrations of Copper and Zinc in Hair Tissue;" June 2011
- Neek, L, et. al; Biological Trace Element Research; "Effect of Zinc and Selenium Supplementation on Serum Testosterone and Plasma Lactate in Cyclist After an Exhaustive Exercise Bout;" July 2011
- Hornyak, M, et. al; Sleep; "Magnesium therapy for periodic leg movements-related insomnia and restless legs syndrome: an open pilot study;" August 1998
- Abbasi, B, et. al; Journal of Research in Medical Sciences; "The effect of magnesium supplementation on primary insomnia in elderly: A double-blind placebo-controlled clinical trial;" December 2012
- Seaman, A; US News; "Zinc may shorten common cold, but side effects common;" 2012
- Medline Plus; "Magnesium Gluconate;" 2014
- Mazidi, P, et. al; The Internet Journal of Internal Medicine; "Hypermagnesemia in the Absence of Renal Failure;" 2008