Calcium and Testosterone


The relationship between calcium and testosterone is unclear. Human observational studies show no correlation between serum calcium and testosterone. Furthermore, one experimental study suggests that calcium supplementation does little to boost testosterone in the sedentary, but might to a bit in athletes, but even this result failed to reach statistical significance. Animal studies suggest that excessive calcium may disrupt the reproductive system, but there is a hint from an in vitro study that a deficiency of calcium might lower the responsiveness of the testicles to luteinizing hormone.

Calcium does not boost testosterone in sedentary individuals, might do so in athletes
35mg/kg calcium (as gluconate)

Observational study: No correlation between levels of total and free testosterone, total estradiol and serum calcium.
Slight relationship with SHBG

Observational study: Vitamin D deficiency and low ionized calcium are linked with semen quality and sex steroid levels in infertile men.

Rat study: Excessive dietary calcium in the disruption of structural and functional status of adult male reproductive system in rat with possible mechanism

In vitro study: Calcium modulates testosterone production in response to luteinizing hormone
Summary: Rat leydig cells were exposed to differing levels of calcium ions and differing levels of luteinizing hormone (the key hormone that tells the leydig cells to produce more testosterone). Without luteinizing hormone, testosterone production was not affected by calcium levels. However, low calcium levels reduced the responsiveness of the leydig cells to luteinizing hormone.
Applicability: Unclear given that we don't know how testicular levels of calcium vary according to modifiable factors like dietary intake or supplementation. If it is modifiable, it is unclear how deficient someone would have to be for this to be an issue. Finally, this study is looking at one variable in isolation. Calcium may influence a range of factors that influence testosterone production beyond the leydig cells. Luteinizing hormone, activin, inhibin are all other factors that influence testosterone levels.