Interaction fact sheet · Synergy
Magnesium and zinc
Compatible combination if the zinc dose stays reasonable.
At usual supplement doses, no notable interference. A very high zinc dose, 142 mg per day, reduced magnesium absorption in one trial.
When zinc interferes with magnesium
Spencer and colleagues measured magnesium absorption and balance in adult men hospitalized in a metabolic research unit, where everything they ate was controlled. They received 142 mg of zinc per day as zinc sulfate, with three levels of calcium intake. Across all groups, zinc significantly reduced magnesium absorption and balance. When groups were analyzed separately, the decrease was significant only at the intermediate calcium intake.
The tested dose is very high: more than five times the adult upper limit of 25 mg per day set in Europe. Common supplements most often provide between 10 and 25 mg of zinc. No study we have identified shows discomfort at these doses, which does not prove that there is none.
How ZMA measures up
ZMA combines zinc, magnesium, and vitamin B6 and is marketed for testosterone, recovery, and sleep. Wilborn and colleagues gave ZMA or a placebo to 42 resistance-trained men for 8 weeks, 30 to 60 minutes before bedtime. Blood zinc increased by 11 to 17%, but the increase was not significant. Anabolic and catabolic hormones, body composition, maximal strength, muscular endurance, and anaerobic capacity did not change compared with placebo.
Gallagher and colleagues tested ZMA in 16 trained men restricted to 4 hours of sleep on two consecutive nights. ZMA improved neither sleep quality nor power during resistance exercise the next morning, compared with placebo and no capsule.
Cautious approach
Add up the zinc from all your products (multivitamin, ZMA, zinc alone) and stay below 25 mg per day without medical advice. If you take high-dose zinc or take it for months, also read the fact sheet zinc and copper. To choose your forms, see why most zinc supplements are poorly absorbed , the comparison of magnesium forms and the magnesium score.
Limits
The Spencer study dates from 1994 and involves small groups of men, a single form of zinc and a very high dose. It says nothing about doses of 10 to 25 mg. The ZMA trials involve young, trained men over no more than 8 weeks: they do not tell us whether the product helps someone deficient in zinc or magnesium. In that case, the deficiency needs to be documented and corrected with a professional.
Main sources
- 01Spencer H et al. Inhibitory effects of zinc on magnesium balance and magnesium absorption in man. Journal of the American College of Nutrition, 1994. PubMed 7836627
- 02Wilborn CD et al. Effects of zinc magnesium aspartate (ZMA) supplementation on training adaptations and markers of anabolism and catabolism. Journal of the International Society of Sports Nutrition, 2004. PubMed 18500945
- 03Gallagher C 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. PubMed 38257144
Frequently Asked Questions (FAQ)
Can you take zinc and magnesium at the same time?
At usual doses, no interference is documented. The Spencer study shows reduced magnesium absorption with 142 mg of zinc per day, more than five times the upper limit set in Europe for adults (25 mg per day). At these doses, the issue is not timing but the zinc dose itself.
Does ZMA improve testosterone or sleep?
Not according to the available trials. In 42 trained men, 8 weeks of ZMA changed neither hormones, strength nor body composition. In 16 sleep-deprived men, two nights of ZMA improved neither sleep nor performance the following morning.