Male-mediated dietary effects on offspring: RCT of walnuts and sperm quality

Rodent models demonstrate that father's diet at the time he produces offspring affects health of his progeny into their adulthood. Human studies also suggest inter-generational effects, for example paternal adiposity linked to offspring low birth weight, although underlying mechanisms are unknown. Sperm transmission of de novo chromosome abnormalities and/or damaged DNA to offspring is one possible mechanism for male-mediated effects. Role of paternal diet on sperm DNA/chromatin integrity has not been well studied in humans although anti-oxidant nutrients are known to be important to overall male reproductive health. We used fluorescence in situ hybridization and COMET single-cell gel assay to explore relationships between sperm chromosome/DNA damage and nutrients in blood (fatty acids, selenium, zinc, folate) plus self-reported dietary consumption determined with the National Cancer Institute (NCI) Diet History Questionnaire and biweekly 24-hour food recalls using NCI Automated-Self-Administered 24-hour Recall assessment tool. The study population of 117 healthy, non-smoking men (ages 20-35) eating a Western style diet were recruited at a major university for a phase II randomized control trial of effects of walnut consumption on male reproductive health. Participants ate their usual diet for three months to capture one complete cycle of spermatogenesis; the intervention group added 75 grams of whole-shelled walnuts per day. Conventional semen parameters of vitality, motility and morphology improved in the walnut group compared to the control group (p=0.003, 0.009, 0.04 respectively). We now use this study population to report on relationships between their dietary data, blood nutrient levels and sperm DNA/chromatin and aneuploidy outcomes.