Several studies have revealed that zinc does indeed improve semen volume and testosterone, and have explained the science behind how it works.
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It had been known since the 1920s that zinc was essential for proper reproductive function in animals.
Zinc was especially concentrated in the testes, and would rise during mating season.
The first study in humans (1977) showed that 100 mg of zinc daily could massively improve testosterone:
400 ng/dL ➜ 815 ng/dL in zinc group
547.5 ng/dL ➜ 320 ng/dL in control
It also lowered pituitary gonadotropins.
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Later studies showed that zinc could not only boost T, but improve other measures of male sexual health.
Low T men given ~44 mg zinc for under 2 months:
‣ More than DOUBLED sperm count
‣ Increased testosterone by over 50%
‣ Increased DHT by over 30%
9/22 men got their wives pregnant, when none could for 5 years prior.
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Other trials confirmed this.
In another study, 50 mg as zinc acetate:
➞ Raised T
➞ Doubled sperm count
➞ Lowered gonadotropins (LH, FSH)
Direct and tight correlation between plasma zinc levels and testosterone.
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Later, it was shown that a high zinc diet could increase seminal volume.
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Sperm quality is highly dependent on zinc.
Men with good sperm motility have much higher zinc levels in the semen.
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WHY zinc is so good for male sexual health:
The main and most obvious role zinc plays is in antioxidant defense.
It is a cofactor for the enzymes superoxide dismutase and metallothionein, which prevent excess reactive oxygen species from damaging cellular compartments in the testes, and driving inflammation in them.
This oxidative stress will directly kill sperm cells, and suppress the expression of steroid producing enzymes.
Zinc also plugs into various enzymes and genetic regulatory proteins that support sexual health.
It supports the entire hypothalamic-pituitary-gonadal axis:
➜ Stimulates GnRH release and supports LH/FSH secretion
➜ Enhances Leydig cell sensitivity to LH, allowing more testosterone output with less stimulation
➜ Boosts transcription of steroidogenic genes like StAR and CYP11A1
➜ Inhibits aromatase, preserving testosterone from conversion to estradiol
➜ Maintains androgen receptor structure and DNA-binding
Zinc also protects the testes directly:
➜ Preserves Sertoli cell (sperm producing cells) function and the blood-testis barrier
➜ Concentrates in seminal fluid, supporting sperm motility, morphology, and DNA integrity
➜ Prevents apoptosis of developing germ cells
➜ Suppresses inflammatory cytokines like IL-1β and TNF-α that impair steroid production
Zinc deficiency leads to high LH/FSH but low testosterone, indicating resistance in the axis. Zinc repletion restores sensitivity, boosts testosterone, and revives spermatogenesis.
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