Not worth it for testosterone, strength and sleep.
The label shows how strong the evidence is, not how big the effect is. Tap a claim to see its papers.
Plausible but thinly tested: in 9 marginally zinc-deficient older men, 3-6 months of zinc raised testosterone from 8.3 to 16.0 nmol/L, and restricting zinc in 4 young men lowered it.[1]
The data come from one small uncontrolled study (no placebo) plus a cross-sectional link between cell zinc and testosterone. Evidence in a different population with no placebo group is Grade C.
Each plate is one paper. Taller = stronger study design, wider = more studies pooled. Tap one.
Cell zinc correlated with testosterone; zinc restriction cut testosterone in young men, and zinc supplements raised it in marginally deficient older men.
Possibly helps: magnesium's benefits appeared more pronounced in older adults and people with alcoholism, groups likely to be low in magnesium, but the pooled strength effects were not significant.[2]
The meta-analysis infers benefit in likely-deficient groups from subgroup patterns rather than a significant pooled effect, and did not test lifters. Evidence only in other populations is Grade C.
Each plate is one paper. Taller = stronger study design, wider = more studies pooled. Tap one.
Magnesium supplementation did not improve muscle strength, power or peak torque overall and showed no benefit in athletes; benefits appeared more pronounced in elderly people and alcoholics.
Not in healthy athletes: two nights of ZMA did not improve sleep in trained men, even when sleep-deprived. Magnesium alone cut time to fall asleep by 17.36 minutes in older adults with insomnia, on low-quality evidence.[3][4][5][6]
ZMA trials in athletes are null but short (two nights); magnesium trials in insomnia are few, at moderate-to-high risk of bias and inconsistent, and a 2026 review does not support it as routine insomnia treatment. Weak, mixed evidence is Grade C.
Each plate is one paper. Taller = stronger study design, wider = more studies pooled. Tap one.
In older adults with insomnia, magnesium shortened sleep-onset time versus placebo, but total sleep time did not change significantly and evidence quality was low to very low.
Across 12 RCTs, magnesium's effects on sleep were inconsistent and low to very low certainty; it is not supported as a routine insomnia treatment.
In recreationally trained men with adequate diets and normal sleep, two nights of ZMA did not change sleep, sprints or cognition; jump height beat placebo but not a no-pill control.
In trained men sleeping 4 hours for two nights, ZMA did not improve sleep quality, fatigue or next-morning lifting power and velocity versus placebo.
No: ZMA raised blood zinc but did not change total or free testosterone in trained or regularly exercising men eating enough zinc.[7][8][9]
An 8-week placebo-controlled trial in 42 trained men and a trial in 14 men with adequate zinc intake found no hormone change, and a systematic review of testosterone boosters found zinc/magnesium among the products that fail. Good null trials is Grade D.
Each plate is one paper. Taller = stronger study design, wider = more studies pooled. Tap one.
Most marketed testosterone boosters failed to increase total testosterone; zinc/magnesium (5 studies reviewed) was not among the exceptions.
In regularly exercising men already eating 11.9-23.2 mg/day of zinc, ZMA raised serum and urine zinc but not total or free testosterone or urinary steroid metabolites.
In resistance-trained men, a ZMA-containing supplement for 8 weeks of training did not change hormones, body composition, strength, muscular endurance or anaerobic capacity versus placebo.
No extra strength, muscular endurance, power or lean mass over 8 weeks of training in trained men; magnesium alone did not improve strength in athletes.[2][7]
A placebo-controlled ZMA training trial was null on every performance and body-composition measure, and a meta-analysis of magnesium trials found no benefit in athletes and active people. Grade D.
Each plate is one paper. Taller = stronger study design, wider = more studies pooled. Tap one.
Magnesium supplementation did not improve muscle strength, power or peak torque overall and showed no benefit in athletes; benefits appeared more pronounced in elderly people and alcoholics.
In resistance-trained men, a ZMA-containing supplement for 8 weeks of training did not change hormones, body composition, strength, muscular endurance or anaerobic capacity versus placebo.
ZMA is a branded blend of zinc (as monomethionine aspartate), magnesium (as aspartate) and vitamin B6. Zinc and magnesium are essential minerals; WHO's dietary reference for zinc is 6.7-15 mg/day. Trained men in one ZMA study already ate about 11.9 mg zinc, 395 mg magnesium and 2.7 mg B6 a day.
Zinc is needed for normal testosterone production: severe zinc deficiency causes hypogonadism, and cutting dietary zinc lowered testosterone in young men. Magnesium is involved in muscle function. The theory is that hard training causes losses that ZMA replaces; in men who already eat enough zinc, extra zinc raises blood zinc but not testosterone.[1][2][8]
Reviewed 03 Oct 2026 · every PubMed ID checked against PubMed
30 mg zinc (as monomethionine aspartate), 450 mg magnesium (as aspartate) and 10.5-11 mg vitamin B6 per daily serving in the ZMA studies
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