In an age when millions of people are taking herbal supplements, it can be easy to forget to take our daily vitamins. It is true that trust in physicians has been in sharp decline for a number of years, but that doesn’t mean we should throw the baby out with the bath water, so to speak.
By some estimates, nearly half of all people are vitamin D deficient, and there is mounting evidence that some of this may be triggering lower than normal testosterone levels. Of course, the lack of vitamin D can be attributed to a number of factors. Diet of course plays a role, but so do our increasing tendencies to stay indoors. Vitamin D can be made by the body when we get enough ultraviolet light exposure (as from sunlight). But if we don’t get enough sunlight , then supplementation is an effective alternative.
✲ Vitamin D does show correlative benefits to testosterone levels.
✲ According to a highly focused study, Vitamin D seems to directly stimulate the cells in the testis of humans.
✲ The only data contradicting these data are taken from men with healthy levels of Vitamin D and/or testosterone.
Results Showing a Correlation
It is often seen in the scientific community that an observational study leads to a test or trial. First, scientists will simply observe a phenomenon, and if the correlation of data is strong enough, they’ll devise a controlled experiment to see if the initial data were more than coincidental.
With vitamin D, it was observed not only that men with deficient levels of Vitamin D had deficient testosterone, but also that these levels followed a seasonal pattern. (Remember, sunlight = Vitamin D.) This observational study took into account data from over 2,000 men, showing a high probability of actual correlation.
Following this study, two important controlled experiments took place. The first sampled tissues and cells from the testis of human males and looked for the prevalence and functions of Vitamin D Receptors (VDR). They found a “marked expression” of these VDR, showing that the very cells of the testis (which produce testosterone) are highly interactive with Vitamin D.
The second study to the more direct approach: they assigned 54 overweight, Vitamin D deficient men to a placebo-controlled trial. The test group received .083 mg of Vitamin D a day for a year. After the trial, the test group had statistically significant increases in all Testosterone levels: an almost 30% increase in Total Testosterone, almost 20% increase in Bioavailable Testosterone, and over a 15% increase in Free Testosterone.
The latest of the studies with positive correlation took the most iron-clad of approaches: they measured the actual cellular activity of Leydig cells (which produce testosterone) when interacting with Vitamin D.
After studying their results, they came as close as scientists ever do to declaring that there is, in fact, a direct causal relationship between Vitamin D and increased testosterone production.
A Bad Study: Cross-sectional Data
Contrary to the stellar results reported above, a cross-section of studies was published that claimed there was no statistical difference in testosterone among men who took Vitamin D and those who did not.
This study gives us a chance to look at why studies need to be read in-depth in order to discern their true data. In reading the article thoroughly, I found that they downplayed all the studies which did show a correlation, and cited multiple studies which only studied men with adequate Vitamin D and testosterone.
In fact, their analysis was based on sheer numbers. By using a study with over 2,000 participants that all had healthy Vitamin D levels that then took extra Vitamin D, and then had no change in testosterone, they skewed their own data.
This study, in effect, does nothing for anyone trying to honestly answer the question: can Vitamin D supplementation help testosterone. Their numbers looked predominantly at men with no deficiencies, which data don’t bear on men looking to supplement their Vitamin D.
Based on the available studies–actual trials with direct controls and tests–Vitamin D supplementation can directly result in higher testosterone. Especially in men with Vitamin D deficiencies. These conclusions have borne out on the observational, clinical, and cellular levels.
Another, ancillary takeaway is that readers should be warned about studies seeming to contradict other data. When looking deeper at the studies with negative results, I found that they did not study specifically Vitamin D deficient men with low testosterone. All the studies that have looked to these populations saw positive results.