Does ZMA Work? What the Research Says

Summary: Does ZMA work? For most people who already eat a reasonable diet, probably not. Independent trials found that ZMA (zinc, magnesium and vitamin B6) didn’t raise testosterone, build muscle or strength, or improve sleep. The only positive study was small, funded by the company that sold it, and co-written by ZMA’s creator. It may help if you’re truly low in zinc or magnesium, but a food-first approach or a simple single-nutrient supplement does that job too.

ZMA has been a gym-bag staple for more than 25 years, sold as a natural way to boost testosterone, recover faster and sleep more deeply. So, does ZMA work? Below we look at what the studies actually found, who might benefit, and what to watch for on the safety side.

What is ZMA?

ZMA is a branded mineral combination of zinc monomethionine aspartate, magnesium aspartate and vitamin B6. The original nightly dose used in research was 30 mg of zinc, 450 mg of magnesium and 10.5 mg of vitamin B6, taken before bed [1]. Many other products now use the ZMA name with slightly different amounts.

The formula was developed by Victor Conte, whose company, SNAC System, held a pending patent on it. At the time of the first ZMA study, Conte was listed with BALCO Laboratories, the company later at the center of a major doping scandal in professional sport [1].

The “aspartate” part simply means the minerals are bound to aspartic acid, an amino acid. Small studies suggest magnesium in this form is absorbed a little better than some cheaper forms, such as magnesium oxide [2]. That doesn’t make it special, though: citrate and other forms do about as well [2].

Zinc, magnesium and vitamin B6 in food

All three nutrients are easy to find in everyday food:

• Zinc: oysters (by far the richest source), beef, pork, poultry, crab, cheese, lentils and fortified cereals. Adult men need about 11 mg a day and women about 8 mg [3]. Zinc from plant foods is less well absorbed, so vegetarians and vegans, people with gut conditions such as celiac or inflammatory bowel disease, and people who drink heavily are more likely to run low [3].
• Magnesium: pumpkin seeds, chia seeds, almonds, spinach, beans, cashews and whole grains. Adult men need about 400–420 mg a day and women 310–320 mg [2]. U.S. survey data suggest almost half of Americans get less than they need from food [2], so magnesium is the nutrient in ZMA you’re most likely to be short on.
• Vitamin B6: fish, chicken, liver, potatoes, chickpeas and bananas. Most adults need only 1.3–1.7 mg a day [4], so the 10.5 mg in ZMA is several times more than you need.

Does ZMA work for testosterone?

This is the big marketing claim, and it rests mainly on one study. In 2000, researchers gave ZMA or a placebo (a dummy pill) to college football players for about 7–8 weeks. Only 27 of the 57 players who started finished the study. The ZMA group’s free and total testosterone went up, while the placebo group’s went down, and the ZMA group gained more leg strength [1].

There are good reasons to be cautious about that result. The study was small, the authors called it “preliminary,” the placebo group started out stronger, and it was paid for by SNAC System, with Conte (who had a financial stake in the product) as a co-author [1].

Independent researchers haven’t been able to repeat it:

• In an 8-week trial of 42 resistance-trained men, a commercial ZMA product didn’t change free or total testosterone, body composition, strength, muscular endurance or anaerobic power compared with placebo. The men’s zinc and magnesium levels were normal to begin with, and the product also contained a few extra herbal ingredients [5].
• A German study of 14 healthy men who exercised regularly and already ate enough zinc found that ZMA raised blood zinc but didn’t change total or free testosterone, or how the body breaks down testosterone [6].

The International Society of Sports Nutrition (ISSN) places ZMA among supplements with “little to no evidence” for building muscle. Its review also points out that the football players in the original study had low zinc and magnesium at the start, so any rise in testosterone may simply reflect topping up a shortfall rather than a true boost [7].

That idea fits with older research on zinc. When healthy young men were put on a low-zinc diet for 20 weeks, their testosterone dropped sharply, and in older men who were marginally low in zinc, zinc supplements raised testosterone back up [8]. In other words, zinc deficiency can lower testosterone, but extra zinc doesn’t push it above normal when your levels are already fine.

Magnesium has a similar story. One small study from Turkey found that 4 weeks of magnesium sulfate raised testosterone in taekwondo athletes and inactive men [9], but it wasn’t blinded or placebo-controlled, used a different form of magnesium, and hasn’t been repeated in larger trials.

Does ZMA build muscle or strength?

Not in independent studies. Besides the 8-week trial above, where ZMA did nothing for strength or muscle mass [5], two newer UK studies tested short-term use:

• In 16 trained men who slept only 4 hours a night for two nights, ZMA didn’t improve sleep or next-morning bench press and squat performance [10].
• In 19 recreationally active men, two nights of ZMA didn’t improve sprint or mental performance. Jump height was better than with placebo, but not better than taking no pill at all, so it’s unlikely to be a real effect [11].

The Australian Institute of Sport, which advises elite athletes on supplements, lists zinc only as a “medical supplement” for treating a diagnosed deficiency, and puts magnesium in its Group C: supplements with no evidence of benefit for athletes or too little research to judge [12].

Does ZMA help you sleep?

Better sleep and recovery is the other big selling point, and for years there were no studies of ZMA and sleep at all. Now there are three, all from the same research group at Liverpool John Moores University, and none found a benefit:

• Two nights of ZMA had no effect on sleep, measured with a wrist activity monitor (actimetry), in healthy active men [11].
• ZMA didn’t improve sleep in trained men who were partly sleep-deprived [10].
• In the largest of the three (69 men), ZMA actually reduced total sleep time by about half an hour compared with placebo or no pill [13].

These were short studies in young men who already slept well and ate enough of all three nutrients, so they don’t rule out a benefit in people who are deficient or have insomnia. For magnesium alone, a review of three small trials in older adults with insomnia found people fell asleep about 17 minutes faster, but the evidence was rated low to very low quality [14]. A trial in Italian nursing-home residents found better sleep with a mix of melatonin, magnesium and zinc [15], but because it included melatonin (a sleep hormone), it tells us little about ZMA.

What about ZMA and tribulus?

ZMA is often sold in a “testosterone stack” with Tribulus terrestris, a plant extract that hasn’t been shown to raise testosterone or improve performance in young men. We couldn’t find any controlled human studies of the combination. Stacking two supplements that each fail on their own isn’t likely to produce a result together. If testosterone support is what you’re after, our reviews of zinc and testosterone and ashwagandha cover the evidence in more detail.

ZMA side effects and safety

In the 8-week trial above, no one reported significant side effects at the usual dose [5]. Still, the standard dose sits close to, or above, some official upper limits, so it’s worth checking your label and any other supplements you take:

• Magnesium: the U.S. upper limit for magnesium from supplements is 350 mg a day for adults [2]. The ZMA product tested in the 8-week trial provided 450 mg of magnesium a day [5], which is above that limit, so check your own label. Too much supplemental magnesium commonly causes diarrhea, nausea and stomach cramps, and people with kidney problems are at higher risk of magnesium building up in the blood [2].
• Zinc: the adult upper limit is 40 mg a day from all sources [3]. ZMA’s 30 mg plus the zinc in your food can take you past it. Taking 50 mg or more a day for weeks can block copper absorption, weaken immune function and lower HDL (“good”) cholesterol [3]. Very high zinc doses (around 142 mg a day) can also interfere with magnesium absorption [2]. In a large U.S. study, men who took more than 100 mg of supplemental zinc a day, or took zinc for 10 years or more, had a higher risk of advanced prostate cancer, although this type of study can’t prove cause and effect [16].
• Vitamin B6: long-term high doses can damage the nerves in the hands and feet (peripheral neuropathy), causing tingling, burning or numbness. The U.S. upper limit is 100 mg a day, but some reports describe nerve problems at lower doses, and the European Food Safety Authority set a much lower adult limit of 12 mg a day in 2023 [4]. Australia’s Therapeutic Goods Administration (TGA) is tightening rules on vitamin B6 products and advises anyone with these symptoms to stop the product and see a doctor [17]. B6 turns up in many supplements and energy drinks, so add up everything you take.
• Medicines: zinc can reduce the absorption of quinolone and tetracycline antibiotics and penicillamine, and thiazide diuretics (water pills) increase zinc loss in urine [3]. Check with your pharmacist if you take any regular medication.

So, does ZMA work?

For most people, the honest answer to “does ZMA work?” is no. Independent studies found no increase in testosterone, muscle, strength or sleep in men who already get enough zinc and magnesium from their diet [5,6,10,11,13]. The one positive trial was small and funded by the product’s maker [1].

If you think you might be low in zinc or magnesium, for example because you eat a mostly plant-based diet, sweat a lot, or have a gut condition, it’s worth talking to your doctor about a blood test. If you are short, more zinc- and magnesium-rich foods or a plain, lower-dose supplement will do the same job as ZMA, often for less money and with less risk of going over the upper limits.

This article is for general information only and isn’t medical advice. Talk to your doctor or another qualified health professional before starting a new supplement. See our medical disclaimer.

References

1. Brilla LR, Conte V. Effects of a novel zinc-magnesium formulation on hormones and strength. J Exerc Physiol Online. 2000;3(4):26–36. https://www.asep.org/asep/asep/BrillaV2.PDF
2. Office of Dietary Supplements, National Institutes of Health. Magnesium: Fact Sheet for Health Professionals. Updated January 6, 2026. https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/
3. Office of Dietary Supplements, National Institutes of Health. Zinc: Fact Sheet for Health Professionals. Updated January 6, 2026. https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/
4. Office of Dietary Supplements, National Institutes of Health. Vitamin B6: Fact Sheet for Health Professionals. Updated June 16, 2023. https://ods.od.nih.gov/factsheets/VitaminB6-HealthProfessional/
5. 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. https://doi.org/10.1186/1550-2783-1-2-12
6. 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. https://doi.org/10.1038/sj.ejcn.1602899
7. Kerksick CM, Wilborn CD, Roberts MD, et al. ISSN exercise & sports nutrition review update: research & recommendations. J Int Soc Sports Nutr. 2018;15(1):38. https://doi.org/10.1186/s12970-018-0242-y
8. Prasad AS, Mantzoros CS, Beck FW, Hess JW, Brewer GJ. Zinc status and serum testosterone levels of healthy adults. Nutrition. 1996;12(5):344–348. https://doi.org/10.1016/s0899-9007(96)80058-x
9. Cinar V, Polat Y, Baltaci AK, Mogulkoc R. Effects of magnesium supplementation on testosterone levels of athletes and sedentary subjects at rest and after exhaustion. Biol Trace Elem Res. 2011;140(1):18–23. https://doi.org/10.1007/s12011-010-8676-3
10. Gallagher C, Austin V, Dunlop KA, et al. Effects of supplementing zinc magnesium aspartate on sleep quality and submaximal weightlifting performance, following two consecutive nights of partial sleep deprivation. Nutrients. 2024;16(2):251. https://doi.org/10.3390/nu16020251
11. Edwards BJ, Adam RL, Drummond D, et al. Effects of an acute dose of zinc monomethionine asparate and magnesium asparate (ZMA) on subsequent sleep and next-day morning performance (countermovement jumps, repeated sprints and Stroop test). Nutrients. 2024;16(15):2466. https://doi.org/10.3390/nu16152466
12. Australian Institute of Sport. AIS Sports Supplement Framework: ABCD classification system. Australian Sports Commission. https://www.ais.gov.au/__data/assets/pdf_file/0006/1082517/AIS-Supplement-Framework-ABCD-System_v5.pdf
13. Edwards BJ, Adam RL, Gallagher C, et al. In males with adequate dietary needs who present no sleep disturbances, is an acute intake of zinc magnesium aspartate, following either two consecutive nights of 8 or 4 h of sleep deprivation, beneficial for sleep and morning Stroop interference performance? Behav Sci (Basel). 2024;14(7):622. https://doi.org/10.3390/bs14070622
14. Mah J, Pitre T. Oral magnesium supplementation for insomnia in older adults: a systematic review & meta-analysis. BMC Complement Med Ther. 2021;21(1):125. https://doi.org/10.1186/s12906-021-03297-z
15. Rondanelli M, Opizzi A, Monteferrario F, Antoniello N, Manni R, Klersy C. The effect of melatonin, magnesium, and zinc on primary insomnia in long-term care facility residents in Italy: a double-blind, placebo-controlled clinical trial. J Am Geriatr Soc. 2011;59(1):82–90. https://doi.org/10.1111/j.1532-5415.2010.03232.x
16. Leitzmann MF, Stampfer MJ, Wu K, Colditz GA, Willett WC, Giovannucci EL. Zinc supplement use and risk of prostate cancer. J Natl Cancer Inst. 2003;95(13):1004–1007. https://doi.org/10.1093/jnci/95.13.1004
17. Therapeutic Goods Administration (Australia). Stronger safety controls to be introduced for products containing vitamin B6. Media release. https://www.tga.gov.au/news/media-releases/stronger-safety-controls-be-introduced-products-containing-vitamin-b6