Vitamin D and Testosterone

Our body requires 24 different vitamins in order to survive, one of which is vitamin D. Some say this is the most important of all, as it is responsible for over 1,000 different functions in the body, one of which is increasing levels of testosterone. While vitamin D is found in low levels in eggs naturally, and dairy products, juices and cereals are often fortified with it, the best way to obtain vitamin D is through sun exposure, Unfortunately, most people no longer get sufficient sun exposure, which has led to about 60% of people in this country now having a deficiency.

All About Vitamin D

Technically, vitamin D isn’t a vitamin but a prohormone. This is because the body can naturally produce it through sun exposure. It is responsible for our bones and teeth by enabling absorption of both phosphorus and calcium. However, it does much more as well. It helps to maintain the endocrine system in men and woman alike.

If you are part of the 60% of people who have a deficiency, which is likely, then over 1,000 of your bodily functions, which include sexual function, hormone secretion, growth and fertility, will also be negatively affected.

About Testosterone

About 95% of testosterone is produced by the testicles in men. Each day, between 3 mg and 10 mg is produced. The other 5% is made by the adrenal glands. Two proteins bind testosterone, which are albumin and SHBG (sex hormone binding globulin). Some testosterone breaks loose from these proteins, which turns it into ‘free testosterone’.

How Is Testosterone Assessed?

Blood tests can be conducted in order to assess testosterone. These will look at:

1. Total testosterone – the sum of bound testosterone and free testosterone
2. Free testosterone
3. Bioavailable testosterone, which is the free testosterone as well as the testosterone that loosely binds to albumin

The exact ranges that testosterone should be at are still being debated on. What has been agreed upon is that it is normal for levels to drop with age. People with inflammatory conditions, HIV, severe kidney disease, cancer or lung disease also often have much lower levels of testosterone. There are also a number of drugs that can cause this, including:

• Chemotherapy
• Excessive, chronic alcohol consumption
• Marijuana
• Nizoral
• Aldactone

Research into Vitamin D and Testosterone

A number of studies have taken place into the links between vitamin D and testosterone. The table below highlights this in greater detail.

Study Results
Effect of vitamin D supplementation on testosterone levels in men Men who took 3,332 IU of vitamin D every day for a year had an increase of 25.2% in testosterone levels compared to a placebo group.
Association of vitamin D status with serum androgen levels in men Men who had adequate vitamin D levels were found to have higher levels of testosterone and lower SHBG counts than those with a vitamin D deficiency.
Additive Benefit of Higher Testosterone Levels and Vitamin D Plus Calcium Supplementation in Regard to Fall Risk Reduction Among Older Men and Women Men who take vitamin D supplementation are less likely to have low levels of testosterone.
Hip Fracture in Elderly Men: The Importance of Subclinical Vitamin D Deficiency and Hypogonadism Elderly men with low vitamin D levels often have low free testosterone, placing them at increased risk of fracture.
Association Between Plasma 25-OH Vitamin D and Testosterone Levels in Men 1362 male subjects were studied to show that there is a direct correlation between vitamin D levels and levels of testosterone. However, their conclusion was that increasing vitamin D levels will only have an effect on testosterone levels if the man has a vitamin D deficiency. Those who are not deficient will not increase their levels of testosterone by taking supplements.
Influence of Ultraviolet Irradiation upon Excretion of Sex Hormones in the Male The best way to get increased vitamin D levels is through sun exposure. This was shown by Dr. Abraham Myerson in 1939, who demonstrated that exposing the chest to the sun for five days increased testosterone by 120%. Exposing the genitals for five days increased it by 200%.
Weak Evidence of Bright Light Effects on Human LH and FSH Bright light may tell the brain to release LH (luteinzing hormone). LH, in turn, tells the testicular Leydig cells to start to create testosterone.
Various studies in animals and humans Vitamin D levels have a positive effect on motility and sperm quality.

Perhaps one of the most important studies took place in Germany. Researchers worked with a population of overweight males who took part in a formal weight loss program for one year. They found that if they were supplemented with 3,333 IU of vitamin D each day, there was no effect on their weight loss. What did happen, however, was a small but significant lowering in levels of cytokine TNF-alpha and triglycerides. Additionally, there was a 5% increase in LDL-C levels in those who took the supplement. Finally, it was shown that testosterone levels also increased.

For the study, 200 men who were fit and healthy but overweight took part. They were provided with education on healthy eating habits and nutrition. They also received a nutritionist’s telephone consultation once per week for the first half of the study. Half of the men received a vitamin D3 supplement, whereas the other half was a placebo. From the 200 men, 54 were chosen at random to have their testosterone levels monitored. Thirty-one of these men received the supplement, the other 23 received the placebo.

Out of these 54 men, the average age was 48 and 50% were smokers. On average, they also had vitamin D deficiencies. At the end of the study, the men had lost an average of 6 kg and those who took a supplement had addressed their deficiency. It was also found that their levels of testosterone had increased. While the increase was small, it was statistically significant.

Naturally, it became important to ascertain whether it was the vitamin D that caused this increase. The primary purpose of the study, however, was to look at weight loss assessment and the testosterone level change was uncovered by chance. Hence, the following thoughts are only theories, but they are being further considered.

1. In mice experiments, those that did not have vitamin D receptors also had lower than average testosterone levels.
2. Testicles have vitamin D receptors, which means the vitamin must have a role.
3. Some studies have demonstrated that blood levels of vitamin D and of testosterone are related.

What is important is to look at all the different studies and evidence together, which does allow people to draw conclusions. The conclusion reasonably seems to be that vitamin D does moderately change levels of testosterone in men. However, these are suggestive conclusions, not definitive. This is true not in the least because other factors, like muscle strength, mood and sex driver, were not taken into consideration. However, regardless of this, the findings are very interesting.

What Do the Studies Tell Us About Testosterone and Vitamin D?

From the studies, we know that:

1. Men who have a vitamin D deficiency are more likely to also have low levels of testosterone.
2. Healthy men who use a vitamin D supplement could see an increase of around 25% in levels of testosterone after one year.
3. People with optimal levels of vitamin D are not likely to positively affect their levels of testosterone through supplementation.
4. The best way to increase testosterone through increased vitamin D is through sun exposure, particularly if the genitals are exposed to the sun.

How Much Vitamin D Should You Take?

The million-dollar question is always how much of a supplement you should take. Unfortunately, there is no clear answer to this yet because there are too many factors that could come into play. Optimum levels of vitamin D are 50 to 70 nanograms per milliliter (ng/ml). Most people can achieve this with a standard over the counter vitamin D supplement or even a multivitamin. Regular sun exposure is even better. If you do decide to supplement, you should always choose a vitamin D3 one, rather than a vitamin D2, which is a synthetic, weaker alternative.

Resources and References:

Low Vitamin D Tied to Testosterone Dip in Healthy Men – Effect of vitamin D deficiency on testosterone level. (Medscape)
Does Vitamin D Affect Testosterone Levels? – Impact of vitamin D on testosterone level. (Vitamin D Council)
Association of Vitamin D Serum with Androgen Levels in Men – Vitamin D and androgen level in men. (
Effects of Vitamin D Supplementation on Testosterone Levels in Men – Vitamin D supplements for increasing testosterone levels in men. (
Additive Benefit of Higher Testosterone Levels and Vitamin D Plus Calcium Supplementation in Regard to Fall Risk Reduction Among Older Men and Women – Vitamin D and calcium supplementation for reducing fall risk. (
Hip Fracture in Elderly Men: The Importance of Subclinical Vitamin D Deficiency and Hypogonadism – Vitamin D deficiency and hip fracture in elderly men. (Europe PMC)
Association Between Plasma 25-OH Vitamin D and Testosterone Levels in Men – Link between vitamin D and testosterone levels in men. (Clinical Endocrinology)
Influence of Ultraviolet Irradiation upon Excretion of Sex Hormones in the Male – UV radiation and sex hormones in men. (Endocrine Society)
Weak Evidence of Bright Light Effects on Human LH and FSH – Effect of bright lights on human luteinizing hormone and follicle-stimulating hormone. (