Low testosterone is associated with levels higher than 40 ng of vitamin D (U-shaped)– July 2014

There are two studies on this page from the same journal

Serum vitamin D levels and hypogonadism in men - 2014

E. Lerchbaum1,2,*, S. Pilz1,3, C. Trummer1, T. Rabe2, M. Schenk4, A. C. Heijboer5 andB. Obermayer-Pietsch1
Andrology, Article first published online: 16 JUL 2014, DOI: 10.1111/j.2047-2927.2014.00247.x

Summary
There is inconsistent evidence on a possible association of vitamin D and androgen levels in men. We therefore aim to investigate the association of 25-hydroxyvitamin D (25(OH)D) with androgen levels in a cohort of middle-aged men. This cross-sectional study included 225 men with a median (interquartile range) age of 35 (30–41) years. We measured 25(OH)D, total testosterone (TT) and SHBG concentrations. Hypogonadism was defined as TT <10.4 nmol/L. We found no significant correlation of 25(OH)D and androgen levels. Furthermore, androgen levels were not significantly different across 25(OH)D quintiles.
The overall prevalence of hypogonadism was 21.5% and lowest in men within 25(OH)D quintile 4 (82–102 nmol/L).
We found a significantly increased risk of hypogonadism in men within the highest 25(OH)D quintile (>102 nmol/L) compared to men in quintile 4 (reference) in crude (OR 5.10, 1.51–17.24, p = 0.009) as well as in multivariate adjusted analysis (OR 9.21, 2.27–37.35, p = 0.002).
We found a trend towards increased risk of hypogonadism in men within the lowest 25(OH)D quintile (≤43.9 nmol/L).
In conclusion, our data suggest that men with very high 25(OH)D levels (>102 nmol/L) might be at an increased risk of hypogonadism. Furthermore, we observed a trend towards increased risk of hypogonadism in men with very low vitamin D levels indicating a U-shaped association of vitamin D levels and hypogonadism. With respect to risk of male hypogonadism, our results suggest optimal serum 25(OH)D concentrations of 82–102 nmol/L.

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Vitamin D and gonadal function in men: a potential inverse U-shaped association? - March 2016

Andrology, DOI: 10.1111/andr.12173,
S. Karras1,2,*, P. Anagnostis1, K. Kotsa2 andD. G. Goulis1

Summary
Accumulating evidence from animal and human studies suggests that vitamin D, apart from its regulatory effects on musculoskeletal health, is involved in reproductive function in both genders. The basis of the interplay between vitamin D and reproduction lays on the presence of both vitamin D receptor (VDR) and 1α-hydroxylase (CYP27B1) enzyme in reproductive organs. In males, VDR are present in testis, epididymis, prostate, and seminal vesicles. In Sertoli cells, whose secretory activities are ion channel-dependent, vitamin D has been shown to stimulate calcium uptake through a nuclear receptor activity. Epidemiological studies support a positive association between serum 25-hydroxy-vitamin D [25(OH)D] concentrations and sperm motility in both fertile and infertile men In addition, large multi-center, cross-sectional studies from Europe and USA have shown positive, linear association between 25(OH)D and androgen concentrations. On the contrary, there are studies that support an inverse U-shaped association, that is, men with both low and high 25(OH)D concentrations demonstrate poorer gonadal function compared with those with intermediate concentrations. Given the rapid increase in over-the-counter use of vitamin D supplements by men that anticipate advantageous health outcomes, the aim of the present commentary is to provide an overview of the studies that present either U-shaped or linear association between 25(OH)D concentrations and male gonadal function.

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See also VitaminDWiki

• Search VitaminDWiki for U-SHAPED 222 items as of July 2014
• Is too much vitamin D bad – possible causes and cures
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• How much vitamin D editorial– Goldilocks Principle – April 2014
• Feel sexier with vitamin D and-or sunshine which seems to disagree with the study on this page
• Fertility and sperm 142 items