Vitamin D Linked to Sperm Count, Motility and Morphology

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Vitamin D levels are linked to Sperm count, motility and morphology

SUMMARY: VITAMIN D EFFECT ON SPERM COUNT, MOTILITY AND MORPHOLOGY

In this study, males with adequate vitamin D levels (> 30ng/ml), had a significantly higher mean sperm count (67.2 vs. 23.5 millions/ml), motility (55.7 vs. 35.0 %) and sperm morphology (4.7 vs. 0.07 %), compared to males with low vitamin D levels (< 20ng/ml).

doi.org/10.1111/and.14147

Background

Supplementing male diets with antioxidants, to reduce oxidative stress induced sperm damage, is a hot topic among researchers currently.

Among the family of antioxidants, vitamin D is of particular interest, due to low levels of vitamin D across the general population.

A previous study found decreased pregnancy rates among males with low levels of vitamin D undergoing timed intercourse with ovulation induction. This may be the result of impaired spermatogenesis, leading to significantly reduced motility and morphology, identified among vitamin D deficient males in other studies.

However significant gaps still exist in our understanding of how vitamin D affects sperm quality, specifically via reactive oxygen species (ROS) and reactive nitrogen species (RNS) which lead to oxidative stress.

Aim

To explore the link between vitamin D and oxidative stress in males with normal and altered sperm parameters.

Methodology

A total of 88 males was recruited for this cross-sectional pilot study after satisfying the inclusion exclusion criteria.

Any males with a history of diabetes, hypertension, arthritis, malignancy, epilepsy, tuberculosis and renal diseases, or diagnosed with secondary infertility, cryptorchidism, testicular trauma, orchitis, testicular hypotrophy, or on any treatment therapy, were automatically excluded from the study to minimise any bias.

Participants were then grouped according to basic semen parameters; Normal (n=44) and Altered (n=44). Normal semen parameters was defined as sperm count > 39×106, sperm motility > 50%, and morphology > 4%, while males with sperm count < 39×106, sperm motility < 50%, and morphology < 4% where recorded as having altered sperm parameters.

Body mass index, body fat %, vitamin D and oxidative stress markers (4-HNE and 3-NT) was then measured according to manufacturer test kit instructions.

Vitamin D levels was also classified into 3 categories: deficient (< 20ng/ml), insufficient (21-29ng/ml) and sufficient (> 30ng/ml).

Results

General characteristics of the 2 groups revealed some differences between them. The mean age of males with normal sperm parameters was higher (37.8 vs. 32.8 years), with moderately lower BMI (24.2 vs 25.9 kg/m2) and a lower proportion of smokers (49.9 vs. 68.2 %).

However mean sperm parameters showed a clear difference between the 2 groups, with a significantly higher sperm count (96.9 vs. 23.6 mill/ml), motility (71.6 vs. 30.3 %) and morphology rate (7.6 vs 0.2 %), in the normal sperm parameter group.

Next analysis of sperm parameters and oxidative stress markers, according to vitamin D levels, revealed a positive relationship between sufficient vitamin D levels and improved sperm parameters (count, motility, morphology), P<0.05. Interestingly no statistically significant relationship between increased levels of vitamin D and decreased oxidative stress marker levels was observed.

Deficient
(< 20ng/ml)
Insufficient
(21-29ng/ml)
Sufficient
(> 30ng/ml)
Vitamin D (ng/ml)13.725.142.7
Sperm count (millions/ml)23.537.967.2
Sperm motility (%)35.036.555.7
Sperm morphology (%)0.071.54.7
4-HNE (ng/L)203.7209.8192.8
3-NT (nmol/L)36.740.846.2
Comparison of sperm parameters and oxidative stress markers according to vitamin D levels

However strictly comparing the mean values of each group did show significantly higher mean levels of 4-HNE (233 vs 158.5 ng/L) among males with altered sperm parameters, along with lower vitamin D levels (34.7 vs. 41.9 ng/ml) overall.

Correlation analysis of the data confirmed a statistically significant relationship between higher levels of 4-HNE and decreased sperm quality across all parameters (count, motility, morphology). On the other hand, increased levels of vitamin D correlated positively with improved sperm count and morphology. Interestingly only a weak association was found between vitamin D and 4-HNE in this analysis suggesting vitamin D supplementation may only have a mild effect on 4-HNE levels.

This finding was further confirmed after comparing mean 4-HNE values in only males with sufficient vitamin D levels. In this comparison, men with normal sperm parameters had significantly lower levels of 4-HNE (157.6 vs 242.5 ng/L) compared to men with altered sperm parameters, even though both groups had sufficient vitamin D levels.

Overall vitamin D levels correlated significantly with all sperm parameters, but not with oxidative stress markers, suggesting vitamin D positive effect on male fertility occurs via an alternate pathway.

Limitations

  1. Intergroup differences
  2. Serum only analysis of oxidative stress markers
  3. Limited number of sperm parameters analysed

Funding

This research was supported by the Pakistan Science Foundation.

Glossary

3-NT (3-Nitrotyrosine)
By product of tyrosine nitration, following the generation of Peroxynitrite, which can disrupt the sperm protein structure and function.

4-HNE (4-Hydroxynonenal)
By product of lipid peroxidation, specifically polyunsaturated fatty acids contained in the sperm plasma membrane.

n
Sample size.

Oxidative stress
An imbalance between reactive oxygen species (free radicals) and antioxidants in the body.

P-value
The probability that a result occurred by random chance.

Similar studies

Yang B, et al. (2012). Associations between testosterone, bone mineral density, vitamin D and semen quality in fertile and infertile Chinese men. https://doi.org/10.1111/j.1365-2605.2012.01287.x

Tartagni M, et al. (2015). Males with low serum levels of vitamin D have lower pregnancy rates when ovulation induction and timed intercourse are used as a treatment for infertile couples: Results from a pilot study. https://dx.doi.org/10.1186/s12958-015-0126-9

Blomberg Jensen M, et al. (2016). Vitamin D deficiency and low ionized calcium are linked with semen quality and sex steroid levels in infertile men. https://doi.org/10.1093/humrep/dew152


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