Myth-buster
A 150-day trial of vitamin D in infertile men found it did not raise serum magnesium — a mineral the same study linked to better sperm quality.
This null result chips away at the popular notion that vitamin D directly improves male fertility; the real driver of the sperm-quality benefits seen in this study may be magnesium, not vitamin D — but this is one of the first trials to test the link, so the picture is far from settled.
Researchers measured vitamin D's effect on magnesium levels in 299 infertile men over 150 days and found no change — despite higher magnesium itself being tied to higher sperm concentration and count. The takeaway: vitamin D supplements didn't budge a mineral that the same study suggests matters for semen quality, but because this is early evidence, it doesn't rule out other roles for vitamin D in fertility.
Where this fits in the evidence
This is among the first studies we've indexed on Vitamin D for Increased Sperm Concentration — treat it as an early signal until more research accumulates.
The study
- Randomized Controlled Trial (RCT)
- n = 299
- 2026-03
- Reproductive biomedicine online
This is a plain-language summary of a research finding, not medical advice. Pillser surfaces research signals to help you decide what's worth investigating — always consult a qualified professional before changing what you take.