Nutritional modifications in male infertility: a systematic review covering 2 decades.

Systematic review of studies in infertile men with male-factor infertility, including sperm dysfunction, oligozoospermia, and asthenozoospermia. The evidence base included randomized trials and prospective studies from several countries evaluating diet quality and micronutrient supplementation.

This systematic review covered nutritional modifications and micronutrient supplementation for male infertility, including saffron (60 mg/day for 26 weeks), L-carnitine and acetyl-L-carnitine regimens, coenzyme Q10 (300 mg daily for 26 weeks or 300 mg twice daily for 48 weeks), selenium-based supplementation, and one selenium plus vitamin A regimen. The included interventions varied widely in dose, duration, and study design.

Overall, nutritional modification appeared potentially beneficial, but the evidence was mixed and heterogeneous. The clearest signal was that a healthy diet may improve at least one semen-quality measure, while diets high in lipophilic foods, soy isoflavones, and sweets may worsen semen quality. Among supplement trials, coenzyme Q10 improved semen parameters in two studies and pregnancy rate in one 48-week trial, whereas saffron and selenium alone did not significantly improve semen parameters. Selenium plus vitamin A improved sperm motility and conception chances.

Evidence was limited by substantial heterogeneity in interventions, populations, outcomes, and study quality. Several included studies were small, and some were open prospective designs rather than randomized controlled trials. Doses and treatment durations varied widely, making comparisons and firm conclusions difficult.