Can sunlight influence fertility and sexual behavior?

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Now that I have your undivided attention, let’s look at the evidence.

Sperm quality and number is superior in men with high vitamin D levels compared with men who are deficient,[i] and other research shows that FEMALE RATS MATED TO DEFICIENT MALES HAVE 73% FEWER SUCCESSFUL PREGNANCIES THAN THOSE MATED TO VITAMIN D-SUFFICIENT MALES.[ii] The ovaries and testes of rats that lack vitamin D receptors (VDR) do not function properly,[iii] and vitamin D deficiency profoundly reduces sperm production;[iv] but that condition is reversible when vitamin D is optimized,[v]--an important fact—since human sperm also contains VDR.[vi]

Dr. Anne Clark assessed the vitamin D levels of about 800 men who were unable to produce a pregnancy in their wives.[vii] About a third had low D levels. After lifestyle changes and vitamin D supplementation, 40% of the men were able to impregnate their wives.

If vitamin D increases fertility, we would expect conception rates to be higher in summer than in winter—and, so it is. Conception rates are highest in late summer.⁵⁴ For those who are having difficulty producing a pregnancy, conception may be as simple as a sunny vacation.

And what about sexuality? There is a direct correlation between high D levels and high testosterone levels in men.[viii] Since testosterone is the “love hormone” in both sexes, libido might be increased by sunlight exposure. Also, D supplementation in testosterone-deficient men increases testosterone by 25% in one year.[ix]

This has been known for decades; in 1939, Dr. Myerson measured circulating testosterone in men and exposed their various body parts to UV.[x] AFTER FIVE DAYS OF CHEST EXPOSURE, TESTOSTERONE INCREASED 120%. WHEN GENITALS WERE EXPOSED, TESTOSTERONE INCREASED BY 200%! Considering the current cultural obsession with sex, I’m surprised that no one has followed up on Myerson’s work. The light emitted from tanning beds is the same type of light used by Dr. Myerson. I expect that many people may have a totally new concept of the much-maligned tanning bed if this information is widely promulgated.

[i] Bjerrum, Poul et al. Vitamin D is positively associated with sperm motility and increases intracellular calcium in human spermatozoa. Human Reproduction 2011;26:1307-1317.

[ii] Kwiecinski, G. et al. Vitamin D is necessary for reproductive functions of the male rat. J Nutr 1989;119:741-44.

[iii] Kinuta, K. et al. Vitamin D is an important factor in estrogen biosynthesis in both female and male gonads. Endocrinology 2000;141:1317.

[iv] Sood, S. et al. Effect of vitamin D deficiency on testicular function in the rat. Ann Nutr Metab 1992;36:203-8.

[v] Sood, S. et al. Effect of vitamin D repletion on testicular function in vitamin-D deficient rats. Ann Nutr Metab 1995;95-98

vi] Corbett, S. et al. Vitamin d receptor found in human sperm. Urology 2006;68:1345-49

[vii] Clark, Anne. Fertility Society of Australia conference in Brisbane - paper presented by D. Clark - research was part of a doctoral study by University of Sydney student Laura Thomson. News.com.au Oct 19 2008

[viii] Wehr, E et al. Association of vitamin D status with serum androgen levels in men. Clin Endocrinol (Oxf) 2010;73(2):243-8

[ix] Pilz, S. et al. Effect of vitamin D supplementation on testosterone levels in men. Horm Metab Res 2011;43(3):223-5

[x] Myerson, A. Influence of ultraviolet radiation on excretion of sex hormones in the male. Endocrinology 1939;25:7-12

Still more for expectant moms: Sunlight/vitamin D during pregnancy increases the strength of bone in children and leads to greater height.

Another new research paper provides one more reason for pregnant women to get out in the sunlight during the season when UVB light is available (UVB light is the wavelength that produces vitamin D); that habit by expectant mothers predicts that their children will have heavier bones that are less susceptible to osteoporosis, and in addition, they will be taller at the age of 9.[1] Greater lean muscle mass in the boys and girls studied was also related to higher UVB exposure during their fetal stage, meaning that both muscle and bone were enhanced-quite an advantage for youngsters considering athletics, and a boon in later stages of life for reducing the risk of osteoporosis and muscle wasting.

Moderate, consistent sunlight exposure to a large area of skin is vital to the health of the pregnant mother and her children. In winter, when no UVB is available in sunlight, and when sunlight itself is far less available, tanning beds are very effective in producing vitamin D (be careful not to burn). For those who prefer not to use tanning beds, vitamin D3 supplementation of 3,000-5,000 IU per day is critical.

[1] Sayers, A. et al. Estimated maternal ultraviolet B exposure levels in pregnancy influence skeletal development of the child. J Clin Endocrinol Metab. 2008 Dec 30. [Epub ahead of print]

Can't get pregnant? Conception may be as easy as 1,2,D3

I have previously posted on vitamin D and fertility, but I think it bears repeating, since many couples have a difficult time in trying to produce a pregnancy.

A recent report adds credence to the idea that infertility may be due in great part to vitamin D deficiency. Dr. Anne Clark, who works at the Fertility First clinic in Sydney, Australia, assessed the blood levels of vitamin D among about 800 men who were unable to produce a pregnancy in their wives. About a third had low levels of vitamin D. Interestingly, after a regimen of lifestyle changes (stopped smoking, coffee drinking and alcohol consumption) and vitamin D supplementation, 40% of the men were able to impregnate their wives, probably due to improvement in the quality of sperm.

Dr Clark stated that "Vitamin D and folate deficiency are known to be associated with infertility in women, but the outcomes of the screening among men in our study group came as a complete surprise." Though it may have surprised Dr. Clark, the results of her findings should not be surprising to those who read my previous blog on vitamin D and infertility. In that blog, I mentioned that female rats mated to vitamin D-deficient males produced 73% fewer pregnancies. Nearly all tissues of the body contain vitamin D receptors (VDR). For the testes to function properly, those receptors must be stimulated by vitamin D.

For women who are having difficulties in conceiving, and for well their husbands who are probably vitamin D-deficient, this information is critically important. Pass it on!