ZMA

Evidence ratingLow

A combination supplement of zinc, magnesium, and vitamin B6. Known for strong marketing claims about boosting testosterone and building muscle, but independent studies have not confirmed hormonal increases. Has some value in correcting zinc deficiency.

An ingredient with still-limited research

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Effects reported in research

Testosterone normalization in zinc-deficient individuals (deficiency correction)

Sleep and recovery support in magnesium-deficient individuals

Vitamin B6 support for protein metabolism

Dosage & timing

Manufacturer recommends 1–2 capsules 30 minutes before bed on an empty stomach.
Typically provides 10–30 mg elemental zinc.

Cautions

•Excessive zinc intake can impair copper absorption, suppress immune function, and cause nausea.
•Avoid continuous supplemental zinc intake above 40 mg/day.

Supporting research

Randomized controlled trial

Effect of zinc and magnesium supplementation on testosterone and insulin-like growth factor-1 in resistance-trained men

European Journal of Clinical Nutrition, 2009

An RCT in 42 resistance-trained men taking ZMA (zinc, magnesium, vitamin B6) for 8 weeks. Although blood zinc and magnesium rose, there were no significant changes in testosterone or IGF-1, and no evidence that ZMA directly enhances strength or hypertrophy. An independent study that contradicts the 'testosterone-boosting' marketing claim for ZMA.

View study details

Last checked: 2026-06-23