Does Sunbathing increase Testosterone?

Written by Ben Bunting: BA, PGCert. (Sport & Exercise Nutrition) // British Army Physical Training Instructor // S&C Coach.


When asked what they would consider their ideal day to be, the majority would answer that it would include a hot, sunny day with a few cocktails. Why? 

There's something good about the sunshine. It improves our mental, emotional, and physical health. We have more energy and are more active. 

Is it a result of an increased testosterone level? This article will look at: 

Vitamin D is the sun's nutrient

Vitamin D comes in two forms - D2 and D3 (cholecalciferol). D3 is more potent and biologically active. Vitamin D is produced when sunlight reaches the skin. UV rays can produce active D3 in this situation. More sun exposure will increase your vitamin D levels. 

Vitamin D is also found in milk, bioactive yogurts, and oily fish like salmon, mackerel, and sardines. 

D3 regulates calcium to maintain healthy teeth and bones. It has also been associated with a protective action against diabetes, cardiovascular disease and certain forms of cancer. 

Vitamin D deficiencies increase the risks of respiratory, autoimmune and cardiovascular diseases as well as the likelihood of falling and breaking bones [1]. This is a vital nutrient. 

Many experts recommend that vitamin D doses over 1000 IU be more effective. 

Sunbathing can help you achieve optimal vitamin D levels. 

In a study in Hormone and Metabolic Research, it was found that testosterone levels were low among men who are vitamin D-deficient, however, when supplemented with 3332 IUs, the levels of T increased by more than 25%. 

The key point: UV exposure increases vitamin D, which reduces cardiovascular diseases and other illnesses. 

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Does sunbathing boost testosterone levels?

Austrian researchers published evidence recently that testosterone levels are seasonal, peaking in august and dropping in winter. 

The researchers found that among the 2,299 males recruited to the study, men with vitamin D levels below 30ng/dL also had low testosterone levels. There was a strong correlation between vitamin D and T. 

Other research has shown that exposure to the sun in early morning can increase luteinizing (LH), an important modulator of testosterone. 

A study in Neuroscience letters [4] exposed 11 young healthy men to bright light over 5 days for one hour. Their LH levels increased by an astounding 69.5%. 

While there was no direct measure of T taken it makes sense that an increase in LH will at least encourage it. 

A study published in Clinical Endocrinology reported [5] that testosterone levels increased in males as the vitamin D level rose. The relationship between D and T is linear up until 75-85nmol/l. After that, the levels of both levels are plateaued. 

Vitamin D also increases muscle mass. Researchers found by adding Vitamin D to the amino acids leucine and insulin - both of which are anabolic, and essential for muscle growth - the pathways required to increase protein syntheses were greatly improved. 

If you're still not convinced of the benefits of sun exposure, a recent study published in the Asian Journal of Sports Medicine by Bhutkar and colleagues [7] wanted to see if regular exposure to the sun for six days a week for 24 weeks would increase muscle strength or endurance. 

Both strength and endurance showed improvements. The results showed that both strength and endurance improved. 

According to the authors, "based on our observations and findings we concluded that Sun Salutation is an excellent exercise for maintaining a high level of fitness". 

Sunbathing stimulates the production of testosterone. It has been proven to improve strength, endurance and body composition. 

Considerations for safety

For lighter-skinned people, it is suggested that they get 15 minutes or less of exposure to the sun per day. Darker skinned people should spend 30 minutes or more per day in direct sunlight. 

Sunscreen blocks ultraviolet rays, limiting the vitamin D exposure to skin and its synthesis. You should also be mindful of the dangers of excessive sunbathing. 

The evidence does not necessarily support the idea that more sun is better. It is vital to monitor sun exposure and use the appropriate protection as needed. 


Vitamin D comes in two forms - D2 and D3. D3 is more potent and biologically active. UV rays stimulate the production of active D3 when sunlight is in contact with skin. This is why vitamin D, also known as the "sunshine Vitamin", is so often called. 

Vitamin D has been shown to have a positive effect on cardiovascular diseases, diabetes, and certain forms of cancer. Sunbathing can help to maintain optimal vitamin D levels, which is important for the male reproductive system. 

Sun exposure is important to stimulate vitamin D production, which in turn increases testosterone. Some research has also shown that sun exposure is important to improve muscle strength, endurance, and mass. 

It is important to know that more sun doesn't necessarily mean better. You should get regular, but not continuous exposure. To ensure safe sun exposure you should follow the guidelines that are appropriate for your skin.

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  1. Holick, MF et al. Health benefits of vitamin D and sunlight: a D‑bate. Nat. Rev. Endocrinol. 2011; 7: 73–75
  2. Pilz S, Frisch S, Koertke H, Kuhn J, Dreier J, Obermayer-Pietsch B, Wehr E, Zittermann A. Effect of vitamin D supplementation on testosterone levels in men.  Horm Metab Res. 2011 Mar;43(3):223-5.
  3. Wehr, E et al. Association of vitamin D status with serum androgen levels in men. Clin Endocrinol (Oxf). 2010; 73(2): 243-8
  4. Yoon, I et al. Luteinizing hormone following light exposure in healthy young men. Neuroscience Letters. 2003; 341: 25–28
  5. Nimptsch, K et al. Association between plasma 25-OH vitamin D and testosterone levels in men. Clin Endoc. 2012; 77(1): 106-112
  6. Salles, J et al. 1,25(OH)2-vitamin D3 enhances the stimulating effect of leucine and insulin on protein synthesis rate through Akt/PKB and mTOR mediated pathways in murine C2C12 skeletal myotubes. Mol Nutr Food Res. 2013; 57(12): 2137-46.
  7. Bhutkar, MV et al. How Effective Is Sun Salutation in Improving Muscle Strength, General Body Endurance and Body CompositionAsian J Sports Med. 2011; 2(4): 259–266
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