Inhibitory effects of zinc on magnesium balance and magnesium absorption in man.
Level 3 - non-randomized controlled study
Controlled metabolic balance trial in adult males without specified randomization
PubMed 7836627 · doi:10.1080/07315724.1994.10718438
What was done
Magnesium absorption and metabolic balances of magnesium and zinc were measured in three groups of adult males in a metabolic research unit during supplementation with 142 mg/day zinc (as zinc sulfate) across calcium intake levels of 230, 500, and 800 mg/day.
What was found
Zinc supplementation of 142 mg/day decreased magnesium balance and magnesium absorption only during the 500 mg/day calcium intake when groups were analyzed separately. When all three calcium intake groups were combined, high zinc intake resulted in a statistically significant decrease in both magnesium absorption and magnesium balance. The abstract reports no exact numerical values, effect sizes, or variance estimates.
Why it matters
This study shows that pharmacological doses of supplemental zinc can interfere with magnesium absorption and worsen magnesium balance in humans.
Limits
The abstract does not state the sample size, study duration, or exact numerical values. The zinc dose tested (142 mg/day) is far above standard dietary intake or typical supplemental levels, and the study included only adult males.
Cited by
- supports Supplemental zinc at doses higher than 142 mg per day limits the bioavailability and absorption of magnesium.