Vitamin D status is not associated with reproductive parameters in young Spanish men

Abstract

Background Relatively low sperm count was reported among young Spanish men in 2013. Several potential culprits have been suggested as explanations for reported trends in sperm counts in Western men, including lifestyles. Although controversial, some studies suggest that semen parameters, such as low sperm motility or abnormal morphology, may be associated with low serum vitamin D levels. Objectives To evaluate associations between semen parameters and reproductive hormones and serum 25‐hydroxyvitamin D (25OHD) status in young Spanish men and to examine these associations in relation to dietary intake of vitamin D. Materials and methods This cross‐sectional study includes 198 university students recruited in 2010–2011 in southern Spain, who provided samples of blood and semen and food frequencies. Semen quality was evaluated by measuring volume, concentration, sperm counts, motility, and morphology, according to the WHO guidelines. Serum samples were analyzed for total 25OHD and reproductive hormones, including FSH, LH, testosterone, inhibin B, and estradiol. Dietary vitamin D intake was assessed using a validated food frequency questionnaire. Associations with semen quality and reproductive hormones were examined using linear regression, adjusting for potential confounders. Results Almost all men had adequate levels of serum vitamin D ‐ only three men (1.5%) were vitamin D deficient (<30 nmol/L) and 17% were insufficient (<50 nmol/L). However, dietary vitamin D intakes were relatively low (below recommended 600 IU/day in 99% of men). Neither dietary intake nor serum vitamin D levels were associated with any sperm parameter or any reproductive hormone (all p ≥ 0.09). Discussion We did not observe an association between vitamin D status and any reproductive parameter in our study population. Conclusions Our results suggest that serum vitamin D levels are sustained in Spanish men despite low dietary intake and therefore low vitamin D does not explain the poor semen quality previously observed in these young Spanish men.

Correlative studies on vitamin D and total, free bioavailable testosterone levels in young, healthy men

“…Results similar to ours were obtained by Rudnicka et al 28 , who showed no association between vitamin D levels and LH, FSH, TT, inhibin B, or estradiol levels (as well as semen parameters) in young men. In addition, Ramlau-Hansen et al 29 also found that LH, TT, and inhibin B levels were not significantly associated with vitamin D. Similarly, Lerchbaum et al 30 indicated that significantly elevated serum vitamin D levels in the subjects had no effect on changes in total testosterone levels in middle-aged men.…”

Dietary vitamin D intake among university students and their habits concerning daily sunlight exposure – a cross-sectional study

“…The vitamin D intake by our student population was lower than mentioned average intakes, but similar to the southern and eastern European countries 8 . There is a gap in the literature regarding vitamin D intake by university student population, and to the available, dietary vitamin D intake by our male students was almost the same as Spanish 20,21 and lower than Swedish 22 male university students. Vitamin D intake by our female students was the same as Spanish female university students 21 .…”

Effects of vitamin D on sex steroids, luteinizing hormone, and testosterone to luteinizing hormone ratio in 307 infertile men

“…16,[26][27][28][29][30] In contrast, vitamin D status was not associated with serum testosterone in healthy younger men. 18,[31][32][33] In this RCT, vitamin D + calcium supplementation improved testosterone/LH ratio in vitamin D insufficient men, which is in accordance with a small RCT supplementing 4000 IU cholecalciferol or placebo to infertile men, which combined indicate that vitamin D rather than calcium increased testosterone/LH ratio. 34 Our results do not elucidate the mechanism behind the increased testosterone/LH ratio caused by vitamin D + calcium supplementation.…”