OtherHumann = 40 (cross-sectional), 4 (deficiency), 9 (supplementation)1996
Zinc status and serum testosterone levels of healthy adults.
Plain-language summary
This study looked at whether zinc levels affect testosterone in healthy men. It compared zinc levels and testosterone in 40 men aged 20 to 80, induced zinc deficiency in 4 young men, and gave zinc supplements to 9 marginally deficient older men. Lower zinc levels were linked to lower testosterone, and restoring zinc raised testosterone in older men. The study suggests zinc plays a role in maintaining healthy testosterone levels.
Key findings
- Lower zinc levels were linked to lower testosterone in men.
- Inducing zinc deficiency in young men lowered their testosterone.
- Zinc supplements raised testosterone in older men with marginal deficiency.
How to analyze the study yourself
- Study type
- This paper has three parts: a snapshot comparison across 40 men, and two arms that measured the same men before and after zinc was first restricted and then replaced. The before-and-after arms can show what changed when zinc changed, which a snapshot cannot, and with four and nine men they show direction rather than size.
- Population
- Healthy men aged 20-80, with separate groups for zinc restriction and supplementation.
- Funding
- Not reported
- Takeaway
- This study found that when zinc was deliberately restricted in healthy young men their testosterone fell sharply, and that giving zinc back to older men who were already mildly deficient raised theirs. It does not show that extra zinc raises testosterone in a man who already has enough. If your diet is light on red meat, shellfish and dairy, it may be worth making sure zinc is covered.