ZMA (Zinc Magnesium Aspartate)
Summary
ZMA combines about 30 mg zinc, 450 mg magnesium and 10.5 mg vitamin B6. In trained men eating adequate diets, it did not raise testosterone or improve strength gains over 8 weeks, and three 2024 crossover trials found no sleep or next-morning performance benefit (grade C). Its magnesium dose exceeds the 350 mg/day upper limit for supplemental magnesium.
Key facts
- 30 mg zinc, 450 mg magnesium and 10.5 mg vitamin B6, taken 30–60 minutes before bed in trials[3][4][5]
- No difference from placebo in 1-RM bench or leg press, endurance, anaerobic power or body composition over 8 weeks of training[1]
- Two nights of ZMA did not improve sleep in three crossover trials; one found less total sleep time[3][4][5]
- 450 mg magnesium is above the 350 mg/day UL for supplemental magnesium; 30 mg zinc and 10.5 mg B6 are below their ULs (40 mg and 100 mg)[7][6][8]
- 5 graded human outcomes on this page
- October 13, 2026
How it works
ProposedZinc and magnesium are essential minerals involved in hormone production and nervous-system signalling, and low intakes have been linked to lower testosterone and poorer sleep. The proposed rationale for ZMA is correcting shortfalls in athletes; trials enrolled men whose diets already met their needs, and ZMA raised blood zinc without changing hormones.[1][2][4]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
At a glance: strongest evidence per outcome
| Outcome | Grade | Effect | Strongest evidence | Rows |
|---|---|---|---|---|
| Strength | Grade C | No effect | RCT · n = 42 · 2004 | 1 row |
| Sleep | Grade C | No effect | Crossover RCT · n = 19 · 2024 | 3 rows |
| Testosterone | Grade D | No effect | Open-label · n = 14 · 2009 | 1 row |
Every graded row
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Strength, power and anabolic hormones during resistance training | No effect | Grade C | RCT · n = 42 · 2004 Resistance-trained men (mean age 27) Form: Commercial ZMA product (zinc as monomethionine and aspartate, magnesium aspartate, B6) that also contained a Mucuna pruriens blend with 50 mg L-dopa · Dose: 30 mg zinc, 450 mg magnesium, 11 mg B6 daily before bed · Duration: 8 weeks Serum zinc rose 11–17% (not significant); there were no differences from placebo in anabolic or catabolic hormones, body composition, 1-RM bench and leg press, muscular endurance or anaerobic capacity. | 18500945 (opens PubMed)Source [1] |
| Sleep and next-morning jumps, sprints and Stroop test | No effect | Grade C | Crossover RCT · n = 19 · 2024 Recreationally trained men with adequate zinc, magnesium and B6 intakes Form: ZMA capsules · Dose: 30 mg zinc, 450 mg magnesium, 10.5 mg B6 before bed · Duration: 2 nights per condition No effect on actigraphy sleep, repeated sprints or Stroop performance; jump height was higher than placebo but not than the no-pill condition. | 39125347 (opens PubMed)Source [4] |
| Sleep quality and next-morning weightlifting after partial sleep deprivation | No effect | Grade C | Crossover RCT · n = 16 · 2024 Trained men after two nights of 4-hour sleep Form: ZMA capsules · Dose: 30 mg zinc, 450 mg magnesium, 10.5 mg B6 before bed · Duration: 2 nights per condition No effect on sleep, fatigue ratings or submaximal bench press and squat power versus placebo or no pill. | 38257144 (opens PubMed)Source [3] |
| Sleep duration and next-morning Stroop performance with 4 or 8 hours in bed | Worsened | Grade D | Crossover RCT · n = 69 · 2024 Men with adequate diets and no sleep problems (33 with 4-hour and 36 with 8-hour sleep opportunity) Form: ZMA capsules · Dose: 30 mg zinc, 450 mg magnesium, 10.5 mg B6 before bed · Duration: 2 nights per condition No effect on morning Stroop performance; ZMA reduced total sleep time by about 0.46 hours versus the other conditions (about 0.94 hours in the 8-hour group). | 39062445 (opens PubMed)Source [5] |
| Serum testosterone and testosterone metabolism | No effect | Grade D | Open-label trial · n = 14 · 2009 Healthy, regularly exercising men aged 22–33 with zinc intakes of 11.9–23.2 mg/day Form: ZMA · Dose: Not stated in the abstract · Duration: Not stated in the abstract Serum and urinary zinc rose, but serum total and free testosterone and urinary steroid metabolite patterns did not change. | 17882141 (opens PubMed)Source [2] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| ZMA (zinc monomethionine aspartate, magnesium aspartate, vitamin B6) | Varies[3][4][5] | Serum zinc rose after ZMA in two trials (significantly in one).[2][1] | No adverse events were reported in the short trials; urine pH and flow rose in one study.[2][3] | Testosterone, strength training and sleep |
Studied doses
Doses studied in human trials ranged from two nights to 8 weeks of a single formula: 30 mg zinc, 450 mg magnesium and 10.5–11 mg vitamin B6 daily, before bed.[1][3][4][5]
Intake reference: No intake reference exists for ZMA itself. Its ingredients have upper limits: 40 mg/day for zinc (food plus supplements), 100 mg/day for vitamin B6, and 350 mg/day for magnesium from supplements and medicines. The usual 450 mg ZMA magnesium dose exceeds the magnesium UL.[7][6][8] Magnesium UL; it covers supplements and medicines only, not magnesium in food. Zinc UL 40 mg and vitamin B6 UL 100 mg (ODS). NIH ODS fact sheet (updated January 6, 2026).
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
Medicines
- Tetracycline and quinolone antibioticsNIH fact sheetMagnesium forms insoluble complexes with these antibiotics; ODS advises taking them at least 2 hours before or 4–6 hours after a magnesium-containing supplement.[7]
- Oral bisphosphonatesNIH fact sheetMagnesium-rich supplements can reduce bisphosphonate absorption; ODS advises separating them by at least 2 hours.[7]
Medicines that can lower levels
- CopperNIH fact sheetThe zinc UL of 40 mg/day is set to protect copper status; ZMA supplies 30 mg zinc before any zinc from food or multivitamins.[6]
Who should be careful
- Sensitivity to magnesium
- High doses of supplemental magnesium often cause diarrhoea, nausea and abdominal cramping, and ZMA's 450 mg exceeds the 350 mg/day upper limit for magnesium from supplements.[7]
- Stacking with other zinc
- Adding a multivitamin or zinc lozenges on top of ZMA can push total zinc past the 40 mg/day upper limit.[6]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
How to read the label
- Check the magnesium lineStandard ZMA servings list 450 mg magnesium, above the 350 mg/day supplemental UL.[3][7]
- Check for extra ingredientsThe 8-week training trial used a product that also contained a Mucuna pruriens blend with 50 mg of L-dopa, so blends differ.[1]
- Label dose vs studied doseAll trials cited here used the same 30 mg zinc, 450 mg magnesium, 10.5–11 mg B6 formula; none tested lower doses.[1][3][4][5]
Cost per studied dose, without the sales pitch
Compare any product you already have by the amount it delivers, not by capsule count or front-of-pack weight.
Cost per studied dose
Enter the price, servings and the amount per serving from your label.
Frequently asked questions
Does ZMA raise testosterone?
Not in men with adequate zinc intake: two studies found no change in total or free testosterone despite higher blood zinc.[2][1]
Does ZMA improve strength?
In 42 resistance-trained men, 8 weeks of ZMA produced no difference from placebo in strength, power, endurance or body composition.[1]
Does ZMA help you sleep?
Three 2024 placebo-controlled crossover trials found no sleep benefit from two nights of ZMA; one found about half an hour less sleep.[3][4][5]
What is in ZMA?
The trials used 30 mg zinc, 450 mg magnesium (as aspartates) and 10.5–11 mg vitamin B6 per day, taken before bed.[3][1]
Sources
- [1]Effects of Zinc Magnesium Aspartate (ZMA) Supplementation on Training Adaptations and Markers of Anabolism and Catabolism.. J Int Soc Sports Nutr, 2004. RCT
- [2]Serum testosterone and urinary excretion of steroid hormone metabolites after administration of a high-dose zinc supplement.. Eur J Clin Nutr, 2009. open-label
- [3]Effects of Supplementing Zinc Magnesium Aspartate on Sleep Quality and Submaximal Weightlifting Performance, following Two Consecutive Nights of Partial Sleep Deprivation.. Nutrients, 2024. crossover-RCT
- [4]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. crossover-RCT
- [5]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. crossover-RCT
- [6]Zinc: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements, 2026. fact-sheet
- [7]Magnesium: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements, 2026. fact-sheet
- [8]Vitamin B6: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements, 2023. fact-sheet
What changed
- Independent review: added magnesium interactions with tetracycline/quinolone antibiotics and oral bisphosphonates from the ODS magnesium fact sheet. All PMIDs re-checked.
- Strict second-pass self-review (no separate reviewer could be dispatched for this batch): all 5 PMIDs re-verified by NCBI esummary (titles and years match the record) and efetch checked for retraction, expression-of-concern and erratum flags (none flagged); every evidence row, key fact, form, dose, label line, FAQ and insight re-read against its abstract, and against PMC full text where the dose or count lives. Fixes: magnesium side-effect wording aligned with the ODS fact sheet. Page set indexable.
- First draft. Every PMID checked against NCBI E-utilities esummary (title and year from the record) and abstracts read for each cited row. Product compositions and doses from PMC full texts (PMC2129161, PMC10820214, PMC11313716, PMC11274203). Upper limits from the NIH ODS zinc, magnesium and vitamin B6 fact sheets, matching the values on this site's zinc, magnesium and vitamin B6 pages.