There are multiple studies which show a link between vitamin D and testosterone. I recommend reading all of my research below if you want to get a better idea of how exactly vitamin d and testosterone interact.
Does Vitamin D Increase Testosterone?
Vitamin D, a fat-soluble vitamin is known for its role in maintaining good bone health by facilitating calcium absorption in intestines. The human body synthesizes vitamin D in the presence of sunlight, and certain dietary sources.
Some recent studies have shown that vitamin D, in addition to its classical role in maintaining bone health, helps to improve cardiovascular function, reduced cancer incidence, heightened immune function and increased testosterone levels. Detailed biochemical studies reveal that vitamin D enhances testosterone levels by stopping the conversion of testosterone to estrogen.
Men looking to boost declining testosterone levels are expected to benefit from vitamin D supplements in a multitude of ways, as this vitamin generally improves bones and muscles along with the immune system. The testicular cells have vitamin D receptors indicating that this vitamin is probably responsible for a few reproductive biochemical processes like the production of hormones.
However, caution must be exercised before taking vitamin D supplements as excess vitamin D can cause deleterious effects on the liver. Taking a blood test prior to supplementing is mandatory. The key important clinical studies establishing the role of vitamin D on testosterone levels are summarized here along with the most significant outcomes.
Vitamin D supplements improve the levels of free and bioactive testosterone
Study: A study was conducted on non-diabetic men enrolled in weight loss programs to explain the correlation between vitamin D and testosterone levels. 200 men started on 3332 IU of vitamin D daily for one year and 164 completed the trial. The levels of free and bio-active testosterone were measured in the blood samples.
Result: Authors observed a significant increase in total, free and bioactive testosterone levels in the group that was administered the supplement.
Conclusion: Vitamin D supplementation at a dose of 3332 IU (83 micrograms) per day for one year increased the testosterone levels in men.
Vitamin D levels are associated with reproductive health parameters
Study: Authors took up this exploratory survey to find the relationship between the vitamin D levels in the body and reproductive parameters like sperm motility and hormone levels. 170 healthy men with an average age of 29 years were taken in the study and blood samples were collected to quantify the levels of various hormones and vitamin D.
Result: Very high and very low levels of vitamin D showed poor levels of reproductive hormones and sperm motility. Optimal levels of vitamin D have been established as 30ng/ml in serum.
Conclusion: Optimal levels of vitamin D in blood help maintain biologically essential levels of reproductive hormones like testosterone, FSH, LH and good progressive motility of sperm.
Vitamin D and testosterone levels are linked
Study: Wehr, Pilz and coworkers took up this study spanning over three years documenting the serum testosterone and vitamin D levels in 2299 men. Blood samples were collected from all the patients referred to angiography, and biochemical tests were used to quantify the levels of vitamin and hormones in the serum.
Result: Authors observed that vitamin D and testosterone levels are linked and optimal levels of the vitamin lead to high testosterone levels. Interestingly, these authors recorded seasonal variations in levels of vitamin D and testosterone and the values peaked in the month of August.
Conclusion: Optimal levels of vitamin D in serum are associated with high testosterone levels.
Very high levels of vitamin D spoil the semen parameters
Study: Authors took up serum vitamin D and reproductive hormone quantification along with semen analysis in 307 men.
Result: High Vitamin D levels were consistently linked with compromised reproductive hormones and semen parameters like sperm morphology and motility. Very few men were deficient in vitamin D in the study sample and authors could not conclude on correlation of low vitamin levels and reproductive hormones.
Conclusion: High Vitamin D levels lead to lower levels of reproductive hormones and semen parameters.
Plausible role of vitamin D receptors in treating prostate cancer
Study: O Maguire and coworkers studied the expression of certain genes involved in regulating the levels of androgenic hormones like testosterone in prostate cancer cell lines (LNCap) in Petri dishes.
Result: Vitamin D binds to its specific receptors that, in turn, increase the expression of genes within the prostate cells that bio-convert the active form of androgens to their inactive form. The inactive form of androgens arrests the growth of cancerous cells.
Conclusion: Vitamin D can be indirectly developed as a therapy for prostate cancer, though these findings are very preliminary and further studies are required to establish the role.
Vitamin D is essential for reproductive development in mice
Study: In this study mice that are genetically devoid of vitamin D receptors were evaluated for the development of male and female gonads. The study hypothesized that without the specific receptors cells, mice cannot take up vitamin D and perform biochemical processes such as the synthesis of reproductive hormones and calcium absorption. Any impairment of reproductive systems indicates low testosterone levels and reduced calcium uptake leads to weak bones.
Result: Mice with no vitamin D receptors show uterine abnormality in female and testicular malformations in male mice. These malformations ultimately lead to reduced or no reproductive hormones like testosterone.
Conclusion: Vitamin D is essential for the development of reproductive organs and the biosynthesis of hormones in both male and female mice.
Vitamin D deficiency in the brain leads to low testosterone levels in male rats
Study: Sonnenberg and coworkers induced vitamin D depletion in rats and measured various enzymes that are responsible for neuroendocrine (brain regulated hormonal secretions) functions. This investigation was taken up to study the effects of vitamin D on brain function.
Result: The levels of key enzymes like choline acetyltransferase were reduced in vitamin D depletion. The testosterone levels were recorded as significantly low in parts of the brain which have a neuroendocrine role (hypothalamus).
Conclusion: Vitamin D levels are directly proportional to the testosterone levels in rats.
So does Vitamin D increase testosterone?
The animal studies, human clinical trials and surveys strongly indicate the important role of Vitamin D in regulating testosterone levels. Vitamin D that has been implicated in the classical role of bone health has an important additional role in the reproductive and immune systems, and in preventing certain cancers.
Testosterone, an important reproductive hormone, is positively regulated by vitamin D and enhanced vitamin D levels have been shown to improve testosterone levels in humans and mice. However, vitamin D in high levels causes the reverse effect on testosterone levels and other semen parameters including a deleterious effect on the liver, suggesting that excessive intake of Vitamin D is not desirable. Vitamin D supplements should be taken only after consultation with a physician and a test on the blood/serum vitamin D levels.