*More research is needed to determine if adding walnuts to the diet will improve birth outcomes for men within fertility clinics and the general population.
Research published in the recent issue of Biology of Reproduction reports that 75 grams (approximately 2.5 oz) of walnuts consumed per day improved sperm vitality, motility, and morphology (normal forms) in a group of healthy young men between 21-35 years of age. These findings are of particular interest to the 70 million couples worldwide who experience sub-fertility or infertility. In fact, in 30-50% of these cases, infertility is attributed to the male partner, and in the United States the prevalence of men seeking help for fertility is estimated at ~3.3-4.7 million.
This research suggests that walnuts provide key nutrients that may be essential in male reproductive health. According to Professor Wendie Robbins, PhD, R.N., F.A.A.N., who led the research at the University of California, Los Angeles, "the positive result of walnuts on sperm may be a result of their unique nutrient profile." Walnuts are the only nut with an excellent source of alpha-linolenic acid (ALA) – the plant-based omega-3 fatty acid, and this study reported higher amounts of ALA provided by walnuts correlated with less frequent aneuploidy. (Aneuploidy is abnormal cell chromosome numbers, which can result in genetic abnormalities such as Down syndrome.)
This randomized, parallel two-group dietary intervention trial evaluated the affect of 75 grams of walnuts/day on semen quality. The study included 117 healthy young men who routinely eat a Western-style diet. Approximately half consumed 75 grams of walnuts per day for 12 weeks, while the remaining half served as the control group. After 12 weeks, compared to the control group, the walnut group experienced improvement in sperm vitality, motility, and morphology – key components in male fertility.