Do vitamin D levels affect sperm quality and IVF/ICSI outcomes?

This study investigated whether vitamin D levels affect sperm parameters and the outcomes of vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). It found that men with low vitamin D levels had worse sperm parameters, but that their outcomes from assisted reproduction were the same.

Sperm count and quality are important measures of male fertility. Factors including age, smoking, exercise, and nutrition can impact sperm parameters.

Vitamin D is involved in heart health, immunity, and reproduction. Vitamin D is synthesized in the skin and can also be found in fortified foods. However, it is very common to have low levels of vitamin D, especially in the winter. Animal studies have found that vitamin D is necessary for male fertility. Some studies have found that vitamin D is important for human male fertility, but the results have not been consistent. It is not clear how vitamin D levels affect sperm quality and the infertility treatments IVF and ICSI.

This study followed 1,308 men from infertile couples undergoing IVF or ICSI. They gave blood and semen samples, and completed questionnaires related to lifestyle factors.

Blood tests were done of a metabolite (type) of vitamin D which is involved in male fertility (25-hydroxy-vitamin D). 27.7% of patients had normal vitamin D levels (over 20 ng/mL). 68.0% had low vitamin D levels (between 10 and 20 ng/mL), and 4.3% of patients were vitamin D deficient (less than 10 ng/mL). Patients in the three groups had similar ages, weights, exercise habits, and use of alcohol and tobacco. They also had similar hormone levels.

236 patients had normal sperm parameters, using World Health Organization criteria. The other 1,072 patients had insufficient sperm parameters. The percentage of sperm that appeared normal under a microscope was significantly higher for patients with normal vitamin D levels than for patients with low or deficient vitamin D (4.2% vs. 3.8% vs. 2.9%). The count of normal sperm was also significantly different depending on vitamin D levels (5.3 vs. 5.1 vs. 3.9 million). This remained significant after adjusting for age and other factors.

268 of the couples underwent IVF or ICSI within 9 months of the blood tests. There was no difference in fertilization rates between men with normal vitamin D levels and those with low or deficient vitamin D levels. There was also no difference in pregnancy rates.

This study found that vitamin D levels affect sperm parameters, but did not find an effect on pregnancy rates from IVF or ICSI.

Because all of the participants were men seeking treatment for infertility, it may not show the full role of vitamin D in male fertility. This study did not investigate whether improving vitamin D intake led to improved male fertility. Also, this study included Chinese men only. The results may not apply to all populations.