Zinc
An essential mineral required for 300+ enzymatic reactions. Involved in immune function, protein synthesis, reproductive health, and wound healing. Deficiency leads to reduced strength, testosterone, and immune function.
A well-studied, foundational ingredient
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Effects reported in research
May restore testosterone and immune function when deficient
Functions as a cofactor in protein synthesis and cell repair
Replenishes sweat-induced zinc losses from exercise
Dosage & timing
- 8–15 mg/day (adult RDA).
- For deficiency correction: 25–40 mg/day short-term.
- Upper limit is 40 mg/day.
Cautions
- •Long-term high-dose use may cause copper deficiency and impair immune function.
- •May cause nausea on an empty stomach — take with food.
Supporting research
Effects of Zinc Supplementation on Testosterone Levels and Immune Function
Nutrition, 1996
An RCT examining the effects of zinc supplementation (45 mg/day, 6 months) on testosterone and immune function in zinc-deficient young and older men. Testosterone was significantly lower in zinc-deficient individuals and recovered to normal range with supplementation. Immune markers (NK cell activity, IL-2, etc.) also improved.
Effect of zinc and magnesium supplementation on testosterone and insulin-like growth factor-1 in resistance-trained men
European Journal of Clinical Nutrition, 2009
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.
Similar supplements
Zinc Picolinate
Confidence: ModerateZinc picolinate
A chelated zinc form bound to picolinic acid. Some research indicates higher absorption than zinc oxide or sulfate. Zinc's role in testosterone levels, immune function, and protein synthesis is well-studied.
ZMA
Confidence: LowZinc, Magnesium, and Vitamin B6 complex
A combination supplement of zinc, magnesium, and vitamin B6. Known for strong marketing claims about boosting testosterone and building muscle, but independent studies have not confirmed hormonal increases. Has some value in correcting zinc deficiency.
Iron
Confidence: HighIron (ferrous fumarate, iron bisglycinate, etc.)
Essential mineral for hemoglobin synthesis in red blood cells. Iron deficiency is common in endurance athletes (especially women and distance runners); supplementation in deficient individuals significantly improves endurance and fatigue.
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