This section explains what sunlight is, and in particular UVB sunlight, which is the sunlight that enables us to produce vitamin D. This section also explains the most common consequences of vitamin D deficiency, the link between vitamin D and testosterone, as well as the link between vitamin D and nitric oxide. In addition, this section tells my experience of getting inadequate sun exposure and how this relates to libido and erectile dysfunction.
We modern human beings spend a lot of timfe inside. We often work or study indoors from the early morning until the late evening. And we often don’t go outside very often other than for getting lunch or a coffee break. The modern human often finishes work or school in the early evening when the sun has faded. As a result, we don’t get much sun exposure. On most days, many of us don’t get any direct sunlight at all.
In fact, many of us are almost paranoid of the sun and it’s abilities to burn and wrinkle our skin, and therefore shun the sun as the enemy. And then when we happen to be exposed, we often put on layers of sunscreen or clothing to block or dim the effects of the sun. In other words, very little unfiltered sunlight falls on the skin of us modern human beings. And in the winter months, particularly for those who live north or south on planet earth. we get even less sun exposure.
However, the sun is a life-giving force. The sun enables life to be sustained on planet earth. Plants, algae and bacteria use light to perform photosynthesis which provides these organisms with energy. In this process, oxygen is produced as a bi-product. These organisms, in turn, serve as food for more complex organisms like fish, bears and modern human beings. Separately, all these complex organisms also need sunlight to survive and thrive. Without the sun, there would be no plants, no trees, no animals and no life
If the sun is such a life-giving force, it is wise to avoid it? Is it wise to always protect ourselves from the sun? Should we instead try to soak up a few more sunrays?
Energy from the sun comes to earth in the form of electromagnetic radiation. The term radiation simply means that the energy travels as rays, or in straight lines. When this radiation is not blocked by clouds, it is experienced as sunshine, which is a combination of light and heat. This electromagnetic radiation from the sun consists of infrared radiation, visible radiation, and ultraviolet radiation.
Visible radiation is the portion of the electromagnetic radiation that has wavelengths that are visible to the human eye. This radiation is allowed to pass through the atmosphere almost un-hindered, however not entirely. For instance, because clean air scatters blue light (wavelengths) more than red wavelengths, the sky during the day appears blue.
The ultraviolet radiation, which is non-visible to the human eye, comes in two forms: A and B. The difference is the wavelength of the radiation, where UVA radiation has the longest waves. UVA radiation is able to penetrate the atmosphere, clouds, smog and even glass. This radiation penetrates through the human skin and deeper into the body than UVB radiation. Although UVA radiation is less intense than UVB radiation, UVA radiation is as much as 30 times more prevalent. UVA radiation also has relatively equal intensity during all daylight hours throughout the year.
UVB radiation, on the other hand, has shorter wavelengths. It is the main cause of sunburn and it only penetrates the skin’s outer layer. It cannot penetrate glass, is partially blocked by clouds, dust, air pollution and the atmosphere in general, and is typically blocked by sunscreens. Unlike UVA radiation, UVB radiation is normally only significant during the few hours of the day when the sun is around its highest point in the sky, because it then has less atmosphere to get through.
There are 5 different forms of vitamin D, but most people have only heard of the two main forms: vitamin D2 and vitamin D3. These two vitamins serve many of the same purposes in the body. We get most vitamin D2 from eating fungi and plants. Vitamin D3 can be obtained from foods such as fatty fish, meat, dairy, etc., but only small amounts will normally be obtained from a normal and healthy diet. The balance, often as much as 90% of our requirement, needs to be provided by the sun. And UVB radiation enables human skin to produce vitamin D3. It is also almost impossible to overdose on vitamin D from sunlight, as the body stops making it when the level approaches sufficiency.
Vitamin D3 can easily be stored in the body for later use. This is not the case for vitamin D2. This means that any vitamin D2 will either have to be used almost immediately after it is consumed, or be discarded. As a result, vitamin D3 is often the preferred vitamin D. The half-life of vitamin D3 circulating in the body is approximately one month, so it can be stored for quite some time and still be effective.
The human body manufactures vitamin D3 when the sun’s UVB radiation hits the skin. When this UVB radiation falls on the skin, a form of cholesterol (called 7-dehydrocholesterol) in the skin absorbs the UVB radiation and in the process synthesizes vitamin D3 in a form called cholecalciferol.
However, this vitamin D3 (cholecalciferol) is still inactive and needs to go through two more processes before it can be utilized by the body. It travels through the bloodstream to the liver, where it’s turned into a component called calcidiol. This calcidiol then travels to the kidneys where it is turned into the active form of vitamin D3, called calcitriol. Calcitriol is then released back into the bloodstream where it can carry out the functions of active vitamin D3, such as regulating how the body uses calcium and phosphorus.
A person with pale skin would need approximately 10-20 minutes in the sun on a sunny day to get one day’s worth of vitamin D3. This would assume that large parts of the body were exposed, such as upper body and legs, and also that the person was not wearing much clothing or sunscreen.
- A large-scale study done in India over a three-year period reported that more than 81% of the participants were vitamin D deficient.
- A study done on 11,218 Australian adults found that 31% of the subjects were vitamin D deficient. The study also showed a large increase in deficiency for older people compared to younger ones.
- A study on 1,912 persons in Canada showed that 58% of men and 61% of women suffered from vitamin D deficiency. This deficiency increased substantially in the winter and spring.
- A study on 325 healthy, young children (12-36 months old) in western Europe reported that vitamin D deficiency was found in 23% of these subjects.
- A study on 316 children aged 5-10 years in western Brittany showed that 52% of these children were vitamin D deficient.
- A study on 13,369 persons in the US reported that more than 75% of the subjects were vitamin D deficient. The study also reported higher deficiencies among persons of darker skin complexions.
Although these numbers vary quite a bit, it seems clear that vitamin D deficiency is common around the world, particularly during the winter months and among older people.
Vitamin D facilitates calcium absorption from foods and helps maintain adequate calcium and phosphate concentrations in the body. Vitamin D is also important in overall skeletal health and growth, cell growth and function, the immune system, proper functioning of muscles and tissues and proper heart function. Vitamin D is also crucial for the expression of more than 10% of a person’s genes.
Rickets and osteomalacia are the classical vitamin D deficiency diseases. Rickets, a disease unique to children and adolescents, is characterized by a failure of bone tissue to properly mineralize, causes softening of the bones and skeletal deformities. Osteomalacia is a similar condition occurring in adults.
Some of the other issues that can arise from vitamin D deficiency are: muscle pain, high blood pressure, restless sleep, multiple sclerosis, osteoporosis, cancer, heart disease, metabolic syndrome, diabetes, autoimmune diseases, arthritis, infertility, Parkinson’s Disease, Alzheimer’s Disease, chronic fatigue syndrome, fibromyalgia and chronic pain.
I am fairly convinced that I have been vitamin D deficient for many years, and particularly after I started working. One of the reasons I say this is because I have spent most of this time inside buildings. I have worked from early morning until fairly late, and not seen much of the sun. I certainly did not see much of the sun during the hours of the day when UVB radiation was available (when the sun is at its highest point during the day).
Another reason why I am convinced I must have been vitamin D deficient, is that I always wore sunscreen while outside on a sunny day. This would significantly reduce the amount of UVB radiation I could absorb.
And the third reason I am convinced I was deficient in vitamin D, is because I did not take any supplements containing vitamin D. Since I did not get much vitamin D from the sun, pretty much all my vitamin D intake came from the foods that I ate. My diet at the time was a normal western diet, and it is practically impossible to obtain adequate levels of vitamin D from this diet. Although I am sure I have consumed some foods and drinks that have been vitamin D fortified, it is still almost impossible to fill up the vitamin D tank from this. Therefore, I am quite convinced that for many years of my life, my body received inadequate levels of this vitamin.
There have certainly been days when I have felt fatigued, have had restless sleep or muscle pains. However, I have no idea whether this was caused by vitamin D deficiency or not. What I do know, is that on days when I get a reasonable dose of sunshine (although not too much), I typically feel charged, sharper, and my libido is normally more intense. I often get random erections and often have frequent sexual thoughts.
I first learned this when I went on a sunny vacation in the Mediterranean a few years ago. We were outside for most of the days, playing in the sun, swimming and just taking it easy. After a few days, I felt an unusual horniness. I had random sexual thoughts (this was far from usual), I had an almost constant tingling sensation in my genitals making me grab and adjust, I had random erections and I also overall had more energy than I normally did. I felt happy and upbeat about being horny, but didn’t think much of it at the time. I assumed it was just random as my horniness level would go up and down from time to time anyways.
It wasn’t until the same thing happened again on another sunny vacation, that I started pondering about this. This time, I went on a week-long vacation in a sunny and temperate part of the world. Again, after a few days I would get random sexual thoughts out of nowhere, often get erections from these thoughts and just be overall horny. It was quite intense and markedly different from my usual state.
I realized then that there was something about these sunny vacations that made my libido jump. I started wondering if the sun could possibly have something to do with it. Was there a link between the sun and libido? It turns out that there is indeed a link, and that the missing link is testosterone.
It turns out that this testosterone link has been known for decades. In 1939, a scientist measured initial levels of circulating testosterone in men, then exposed their various body parts to UVB radiation, and then re-measured the circulating testosterone levels. After five days of chest exposure sufficient to cause reddening, circulating testosterone increased by 120%. After the genital area had been exposed, testosterone levels increased by 200%. After eight days without additional UVB exposure, the testosterone returned to initial levels. So it had already been discovered a long time ago that the sun could impact a man’s testosterone levels.
Testosterone is an essential hormone for sexual health. Certain levels of testosterone are necessary in order for a man to both have a normal sex drive and also for him to achieve and maintain an erection. To learn more about testosterone on Truelibido, please go here.
A more recent research study reviewed the relationship between vitamin D levels and testosterone levels in 2,299 men. The study found that there was a strong correlation between these two variables. Men with high levels of vitamin D also generally had high levels of testosterone, and vice versa. This research also reported a seasonal pattern, with both vitamin D and testosterone levels bottoming at the end of the winter and peaking at the end of the summer.
Another research study analysed whether vitamin D supplementation influenced testosterone levels. 200 men were split into two groups: One group was given 3,332 IU vitamin D daily for 1 year, and the other group was given a placebo. Initially, the group as a whole was vitamin D deficient, and their testosterone levels were at the lower end of their normal ranges. After one year, the group taking the vitamin D supplement saw an increase in total testosterone levels and free testosterone levels of 25% and 20%, respectively, while the placebo group saw no increases.
In addition to the impact vitamin D has on testosterone, it also has a positive effect on nitric oxide levels. This is because vitamin D supports and enhances the manufacturing of the enzyme nitric oxide synthase. This enzyme in turn is what produces the molecule called nitric oxide. And this nitric oxide is produced in the inner linings of the blood vessels called the endothelium. When this nitric oxide is produced it makes the blood vessels expand, or dilate. When blood vessels in the penis are expanded, blood can flow freely to the penis to fill it with blood so that an erection can start to form.
A study that was done on rats to measure this relationship, subjected young rats to vitamin D deficiency and then measured the impact on nitric oxide. The researchers found that not only did vitamin D deficient young male rats have elevated blood pressures and heart rates, but also that their endothelium-derived nitric oxide dilation was reduced by 50% compared to the control group. The study concluded that early life vitamin D deficiency is associated with endothelial vasodilator dysfunction.
Research has shown that vitamin D is important for both testosterone and nitric oxide production. If a person is deficient in vitamin D, he is likely to have impaired testosterone and nitric oxide levels, both of which are essential for a strong libido and for the ability to get reliable erections. However, as with most (if not all) vitamins, minerals, fatty acids, hormones, etc. – problems arise when these are not present in adequate amounts. A person that is vitamin D deficient may see fantastic result from supplementing with vitamin D, but a person that is already fully stocked with vitamin D will probably see no positive impact from supplementing with the vitamin. Put differently, any supplement or herbal remedy, will normally only have any positive effect if it can rectify a deficiency.
Armas LA, Hollis BW, Heaney RP. Vitamin D2 is much less effective than vitamin D3 in humans. J Clin Endocrinol Metab. 2004 Nov. 89(11):5387-91.
Autier P, Gandini S. Vitamin D supplementation and total mortality: a meta-analysis of randomized controlled trials. Arch Intern Med 2007; 167:1730-7.
Bogh MK, Gullstrand J, Svensson A, Ljunggren B, Dorkhan M. Narrowband UVB three times a week more effective in treating vitamin D deficiency than 1600 IU oral vitamin D(3) /day: a randomized clinical trial. Br J Dermatol. 2012 May 25.
Chin KY, Ima-Nirwana S, Wan Ngah WZ. Vitamin D is significantly associated with total testosterone and sex hormone-binding globulin in Malaysian men. Aging Male. 2015 Sep;18(3):175-9. doi: 10.3109/13685538.2015.1034686.
Chiu KC, Chu A, Go VL, Saad MF. Hypovitaminosis D is associated with insulin resistance and beta cell dysfunction. Am J Clin Nutr 2004; 79:820-5.
Daly RM, Gagnon C, Lu ZX, Magliano DJ, Dunstan DW, Sikaris KA, Zimmet PZ, Ebeling PR, Shaw JE. Prevalence of vitamin D deficiency and its determinants in Australian adults aged 25 years and older: a national, population-based study. Clin Endocrinol (Oxf). 2012 Jul; 77(1):26-35. DOI: 10.1111/j.1365-2265.2011.04320.
Davis CD, Dwyer JT. The ‘sunshine vitamin’: benefits beyond bone? J Natl Cancer Inst 2007; 99:1563-5.
Freedman DM, Looker AC, Chang S-C, Graubard BI. Prospective study of serum vitamin D and cancer mortality in the United States. J Natl Cancer Inst 2007; 99:1594-602.
Garland FC, Garland CF, Gorham ED, Young JF. Geographic variation in breast cancer mortality in the United States: a hypothesis involving exposure to solar radiation. Prev Med. 1990 Nov. 19(6):614-22.
Greene-Finestone LS, Berger C, de Groh M, Hanley DA, Hidiroglou N, Sarafin K, Poliquin S, Krieger J, Richards JB, Goltzman D; CaMos Research Group. 25-Hydroxyvitamin D in Canadian adults: biological, environmental, and behavioral correlates. Osteoporos Int. 2011 May; 22(5):1389-99. DOI: 10.1007/s00198-010-1362-7.
Hammoud AO, Meikle AW, Peterson CM, Stanford J, Gibson M, Carrell DT. Association of 25-hydroxy-vitamin D levels with semen and hormonal parameters. Asian J Androl. 2012 Nov; 14(6):855-9. DOI: 10.1038/aja.2012.77.
Holick MF, Binkley NC, Bischoff-Ferrari HA, Gordon CM, Hanley DA, Heaney RP, Murad H, Weaver CM. Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab 2011; 96:1911-30.
Holick MF, Chen TC. Vitamin D deficiency: a worldwide problem with health consequences. Am J Clin Nutr. 2008 Apr; 87(4):1080S-6S.
Holick MF. Vitamin D Deficiency. N Engl J Med 2007; 357:266-281. July 19, 2007. DOI: 10.1056/NEJMra070553.
Holick MF. Vitamin D: importance in the prevention of cancers, type 1 diabetes, heart disease, and osteoporosis. Am J Clin Nutr. 2004 Mar; 79(3):362-71.
Lee DM, Tajar A, Pye SR, Boonen S, Vanderschueren D, Bouillon R, O’Neill TW, Bartfai G, Casanueva FF, Finn JD, Forti G, Giwercman A, Han TS, Huhtaniemi IT, Kula K, Lean ME, Pendleton N, Punab M, Wu FC; EMAS study group. Association of hypogonadism with vitamin D status: the European Male Ageing Study. Eur J Endocrinol. 2012 Jan;166(1):77-85. doi: 10.1530/EJE-11-0743.
Lerchbaum E, Pilz S, Boehm BO, Grammer TB, Obermayer-Pietsch B, März W. Combination of low free testosterone and low vitamin D predicts mortality in older men referred for coronary angiography. Clin Endocrinol (Oxf). 2012 Sep; 77(3):475-83. DOI: 10.1111/j.1365-2265.2012.04371
Lindqvist PG, Epstein E, Landin-Olsson M, Ingvar C, Nielsen K, Stenbeck M, Olsson H. Avoidance of sun exposure is a risk factor for all-cause mortality: results from the Melanoma in Southern Sweden. Journal of Internal Medicine. 2014, 276; 77-86.
Looker AC, Pfeiffer CM, Lacher DA, Schleicher RL, Picciano MF, Yetley EA. Serum 25-hydroxyvitamin D status of the US population: 1988-1994 compared with 2000-2004. Am J Clin Nutr 2008; 88:1519-27.
Merlino LA, Curtis J, Mikuls TR, Cerhan JR, Criswell LA, Saag K. Vitamin D intake is inversely associated with rheumatoid arthritis: results from the Iowa Women’s Health Study. Arthritis Rheum 2004; 50:72-7.
Metropolis Healthcare Limited. 75% of Indians suffer vitamin deficiency: Study. 18th Oct 2015.
Munger KL, Levin LI, Hollis BW, Howard NS, Ascherio A. Serum 25-hydroxyvitamin D levels and risk of multiple sclerosis. JAMA 2006; 296:2832-8.
Myerson A, Neustadt R. Influence of Ultraviolet Irradiation upon Excretion of Sex Hormones In the Male. Endocrinology:25; 7, 1939.
Nimptsch K, Platz EA, Willett WC, Giovannucci E. Association between plasma 25‐OH vitaminD and testosterone levels in men. Clin Endocrinol (Oxf). 2012 Jul; 77(1):106-12. DOI: 10.1111/j.1365-2265.2012.04332.
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. DOI: 10.1055/s-0030-1269854.
Tare M, Emmett SJ, Coleman HA, Skordilis C, Eyles DW, Morley R, Parkington HC. Vitamin D insufficiency is associated with impaired vascular endothelial and smooth muscle function and hypertension in young rats. J Physiol. 2011 Oct 1; 589(Pt 19):4777-86. DOI: 10.1113/jphysiol.2011.214726.
Thomas GN et al. Vitamin D levels predict all-cause and cardiovascular disease mortality in subjects with the metabolic syndrome: the Ludwigshafen Risk and Cardiovascular Health (LURIC) Study. Diabetes Care 2012 May; 35(5):1158-64.
Wang N, Han B2, Li Q3, Chen Y4, Chen Y5, Xia F6, Lin D7, Jensen MD8, Lu Y9. Vitamin D is associated with testosterone and hypogonadism in Chinese men: Results from a cross-sectional SPECT-China study. Reprod Biol Endocrinol. 2015 Jul 16; 13:74. DOI: 10.1186/s12958-015-0068-2.
Wehr E, Pilz S, Boehm BO, März W, Obermayer-Pietsch B. Association of vitamin D status with serum androgen levels in men. Clin Endocrinol (Oxf). 2010 Aug; 73(2):243-8. DOI: 10.1111/j.1365-2265.2009.03777.
Wolpowitz D, Gilchrest BA. The vitamin D questions: how much do you need and how should you get it? J Am Acad Dermatol 2006; 54:301-17.
Yoon I, Kripke D F, Elliott J A, Youngstedt S D. Luteinizing hormone following light exposure in healthy young men. Neuroscience Letters 341 (2003) 25–28.