Men's dietary habits affect their infertility

In an analysis of dietary intake, 83% of infertile men were found to have a low intake of fruits and vegetables (less than five servings/day), versus only 40% of controls (p=.0036). Men who had the lowest intake of antioxidants had the lowest sperm motility, lead author Vivian Lewis, MD, a member of the University of Rochester's division of reproductive endocrinology and professor of obstetrics/gynecology, reported at the American Society for Reproductive Medicine annual meeting here.

Reactive oxygen species contribute to male infertility by damaging sperm DNA and motility and by impairing binding to the oocyte. The University of Rochester study compared the dietary intake of antioxidants between infertile and fertile men and correlated these data with semen parameters.

After conventional semen analysis, aliquots of semen were frozen to measure sperm DNA integrity using sperm chromatin structure assay. Total antioxidant capacity of seminal plasma was measured, Block Food Frequency questionnaires were administered to characterize diet, and recommended daily allowance levels of vitamins A and C and selenium were established. Chi-square and Pearson correlation analysis methods were applied to the data.

In addition to eating fewer fruits and vegetables, the infertile group had a lower mean intake of vitamin C (104 mg/day vs. 152 mg/day; p=.034) and more men with levels of vitamin C below the RDA level (40% vs. 20%; p=.0014). No difference was observed between the two cohorts in proportions of men whose selenium and vitamin E consumption were low.

Phytoestrogens found beneficial

In a related study on the same cohort, the researchers also found that dietary isoflavones might be an important factor in male infertility.

Epidemiologic and experimental studies have found that soy isoflavones may prevent a variety of human diseases. In vitro, the antioxidant activity of the isoflavone genistein has been shown to prevent sperm DNA damage to a greater extent than ascorbic acid or alpha-tocopherol do. In an aromatase knock-out murine model, dietary phytoestrogens partially prevented spermatogenic defects; however, no reports are available on the effects of dietary phytoestrogens on semen parameters in infertile men, said lead author Gyun Jee Song, PhD, a postdoctoral fellow in the department of obstetrics and gynecology at the University of Rochester.

The study found that mean levels of genistein and daidzein were higher in fertile control men than those of infertile men (1,722 ±714 μg/day vs. 529 ±183 μg/day, respectively, for genistein and 788 ±327 μg/day vs. 241 ± 84, respectively, for diadzein; p<.05). Interestingly, the levels of these isoflavones were higher in men with good sperm DNA integrity than were those in men with poor sperm integrity (p=.08).