Vitamin D for Testosterone

Essential for men’s virility and testosterone production, Vitamin D is widely deficient and declines with age.

Evidence makes it pretty clear that Vitamin D is tied to healthy T-levels in men. The only question is, how does it work? Nobody knows (yet), but some possible bio-activities and pathways include:

• Vitamin D Receptors (VDRs) are present in the testes, prostate and sperm. Some believe this reflects Vitamin D’s key roles in reproductive health.
• Vitamin D-metabolizing enzymes are present in the “T-factory” Leydig Cells, suggesting D may be involved in testosterone synthesis.
• D boosts calcium absorption. Some research shows men experience a bigger jump in T levels when they combine strength training with calcium.¹
• It might keep SHGB in check. SHGB hormone binds, neutralizes and diminishes active free testosterone. Vitamin D might boost T by subtracting SHGB.

Other Benefits for Men

• Beyond testosterone support, Vitamin D is good for bone strength, immune health, sperm motility, muscle metabolism and physical performance.

Overview

Most known for helping immunity and bone density, Vitamin D recently went from relative obscurity to red-hot sales as an “overall health” vitamin. The new scoop, however, is that Vitamin D boosts T–and it appears to do this very well. Vitamin D, especially in the superior D3 form, has now become a popular men’s supplement for testosterone and more.

What we know: Plenty of strong evidence correlates good Vitamin D status to high T-levels. One large population study found the inverse to be true, as well. In this study, Vitamin D deficiency was tied to hypogonadism: Teste shrinkage and man-boob growth caused by exceedingly low T-levels.²

Science doesn’t know how Vitamin D boosts T, at least not yet. But its location may be a hint: Vitamin D, Vitamin D Receptor sites (VDRs), and Vitamin D-metabolizing enzymes are all highly concentrated in the male reproductive system… including within testosterone pathways.

• The male reproductive tract has been identified as “a target tissue for vitamin D.”³ This suggests Vitamin D may be involved in masculine health and androgen (male sex hormone) production.

The big problem with D? We’re just not getting it.

When exposed to sunlight, our skin can synthesize Vitamin D… But many simply aren’t getting enough sun. Those who bask in sunshine and (wisely) use sunblock may not be getting D benefits: Even using a weak SPF 8 sunblock will reduce skin Vitamin D synthesis by 95%.⁴

In our daily diets, Vitamin D can be a little challenging, but doable: It is found in milk (via fortification), and in some fatty fish. Despite dietary sources and the ABSOLUTELY FREE Vitamin D that can be obtained by standing out in the sun for a few minutes, most men fail to get enough Vitamin D. This nutritional shortfall is a lot worse than you might think:

The Most Widespread Nutritional Disorder in the World…

… is Vitamin D deficiency. In America, some research suggests nearly 75% of adults are insufficient in Vitamin D. Globally, 1 BILLION people are believed to be insufficient!⁵ Falling short on D could cause big problems for  men’s testosterone levels, especially as we get older.

Part of the problem is, Vitamin D is like a nutritional puzzle. As we age, we need more Vitamin D. But as we age, we also lose the ability to absorb and use Vitamin D. Getting Vitamin D is so challenging, researchers have acknowledged that “supplement use is an important contributor to achieve minimum target levels.”⁶

Since it appears to have a role in healthy testosterone and is apparently difficult for men to get enough of, the best T-booster supplements will usually have a good amount of Vitamin D. Let’s look at some of the research, and see why Vitamin D’s place in T-booster supplements seems to be backed by science.

Research

Animal Research

In one study on male rams, Vitamin D (as D3) was shown to activate and energize the testes’ Leydig Cells (“T-factories”). Then, when combined with Luteinizing Hormone (LH), D3 appeared to significantly boost testosterone (ram study).⁷ This ram study is intriguing because it suggests a “mechanism of action” that’s consistent with its presence in the male reproductive tract.

• To us, this admittedly early animal research suggests that Vitamin D might first signal the testes to make testosterone… and then might be used in the process of forming T, releasing T, or both.

Human Research

Human studies are where Vitamin D holds the most weight for boosting T. Check out these three clinical trials, and note their similarities:

Vitamin D and Testosterone Strongly Linked in Korean Men

652 Korean men over the age of 40 were tracked and tested for fasting blood levels of Vitamin D, total testosterone and free testosterone. At study’s end, researchers reported that higher D levels were tied to higher total and free testosterone levels in the men. Because of its apparent T-boosting activity, researchers suggested Vitamin D might be a safe, cheap way to “treat hypogonadism” in men.

• This study also had two surprising side-discoveries: When the study began, 49% of the 652 participants were found to be deficient in vitamin D–which instantly validated their course of study. Researchers also found that subjects who consumed the most alcohol had the highest T levels, an anomaly that creates more questions than answers.⁸

Vitamin D Supplementation Seems to Boost Testosterone in Overweight Men

In a study of 165 healthy-but-overweight men who were dieting, researchers administered either 3,332 IU Vitamin D or placebo daily for 1 year. At the study’s conclusion, researchers reported that the supplement group experienced a significant across-the-board T-boost:

• Total testosterone levels  went from 10.7 ± 3.9 nmol/l to 13.4 ± 4.7 nmol/l; p < 0.001
• Bioactive testosterone levels went from 5.21 ± 1.87 nmol/l to 6.25 ± 2.01 nmol/l; p = 0.001
• Free testosterone levels went from 0.222 ± 0.080 nmol/l to 0.267 ± 0.087 nmol/l; p = 0.001

Researchers in this study concluded D supplementation “may increase testosterone levels.”⁹

Big study of 2,299 German Men finds D status correlates to healthy T

A team of German researchers investigated how Vitamin D levels might affect the hormone levels of a fairly large pool of participants: 2,299 men. Researchers discovered that men with sufficient Vitamin D had significantly higher levels of testosterone and a better Free Androgen Index (FAI) ratio of T to SHBG (female sex hormone).¹⁰

• Higher D levels link to lower SHBG levels. Since SHGB binds to testosterone and neutralizes it, this “blocking” bio-activity of D could be helpful for T-levels.¹¹

Our take: Vitamin D seems to be an effective T-Booster by strong association.

We have reviewed some fairly large studies on Vitamin D and testosterone that seem to reach the same conclusions:

• When Vitamin D levels are high, testosterone levels are high.
• When Vitamin D levels are low, testosterone levels are low.

Abundant evidence suggests Vitamin D is strongly correlated to healthy T-levels. Where evidence seems to be lacking, however, is in a definitive explanation of D’s exact T-boosting mechanisms of action. Scientists don’t know how Vitamin D does it, but many seem to agree: It works for boosting T.

Dosage

What does the “IU” in Vitamin D dosage mean? It stands for “International Units,” a numeric measure of Vitamin D’s bio-activity, rather than its weight (like mg). An approximate conversion to weight: 1 microgram (mcg) of Vitamin D = 40 IU. Some Vitamin D dosage notes:

• Recommended daily allowance for men up to age 70: 600 IU
• Recommended daily allowance for men up to age 70+: 800 IU
• Tolerable upper intake level for men: 4,000 IU (100 mcg)
• Retail dosage range: 400 IU – 10,000 IU
• One glass of fortified milk supplies 100 IU of Vitamin D
• T-benefits have been documented at 3,000+ IU daily

The IU thing is kind of annoying, since we’re all conditioned to evaluate supplement dosages as a measure of weight. But, now you know how IU works in Vitamin D supplements.

Side Effects

Vitamin D is very well tolerated and rarely causes problems. Very mild adverse events like sleepiness, dry mouth, upset stomach and weakness have been reported.

The National Institute of Health (NIH) says taking 4,000 IU of Vitamin D daily might be risky because of its potential to dramatically raise blood calcium to unsafe levels. But right away they also acknowledge that higher Vitamin D doses are required in cases of deficiency. It’s a mixed message, but one NIH tip is clear: Only take mega-dose Vitamin D under a doctor’s direction.

Available Vitamin D Forms

Vitamin D2 (ergocalciferol): This form, invented in the 1920s to fight rickets, produces D2 by exposing foods to UV radiation. Despite some marketing claims, D2 may be absorbed just as well as D3. D2 spikes blood levels, but crashes fast.

Vitamin D3 (cholecalciferol): D3 spikes and sustains blood levels, making it 3X as potent as D2, Vitamin D3 is the natural form that your skin makes when exposed to sunlight.¹⁴ The body seems to prefer D3, and uses it with far greater efficiency than it does D2.

Inside Scoop: Don’t Step in D2

The supplement industry has almost completely phased out D2 at this point. D3 is so much better, and everybody knows it. If you buy a straight-D supplement, most will be D3. But be warned: Sketchy brands will still try to pawn off D2… because it’s a cheap ingredient that improves their profit margins.

• The dirty trick: They hide cheap, inferior D2 in big complexes with lots of ingredients… so no one will notice.

If you’re buying any kind of complex with Vitamin D–multivitamins, bone health formulas, T-boosters–check to see what kind of Vitamin D they are using. If it’s D2, ditch that brand altogether.