BODYDATA
Research
Study type: Randomized controlled trialConfidence: Low

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

Koehler KParr MKGeyer HMester JSchänzer W

Year2009
Sample sizen=42
JournalEuropean Journal of Clinical Nutrition
AuthorsKoehler KParr MKGeyer HMester JSchänzer W

Evidence is still limited and needs further study

Summary

Summary

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.

Source (read the original)

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DOI: 10.1038/ejcn.2008.64

Key Findings

Key findings

  • 1

    Blood zinc and magnesium levels increased, but no significant difference in testosterone

  • 2

    No significant changes in IGF-1 observed

  • 3

    No evidence that ZMA directly enhances strength or muscle hypertrophy

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Last checked: 2026-06-23