Walnuts have been found to give men a boost in fertility, according to researchers at the University of California Los Angeles. Researchers at the UCLA School of Nursing recently published a study in the “papers in press” section of the peer-review journal Biology of Reproduction.

According to the UCLA and the American Society for Reproductive Medicine, one in six couples are infertile—40 percent of these couples are infertile due to the male. UCLA researchers say the study, entitled self-explanatorily “Walnuts Improve Semen Quality in Men Consuming a Western-Style Diet: Randomized Control Dietary Intervention Trial,” is the first to examine the repercussions of plant sourced omega-3 on sperm. Researchers say the results are promising.

Involving two groups of 117 men between 21 and 35 over the course of 12 weeks, UCLA says researchers added 75 grams of whole-shelled walnuts to the variable group’s diet. UCLA says the control group was asked to avoid tree nuts and continue their normal Western-style diet. Wendie Robbins, a UCLA School of Nursing and Fielding School of Public Health professor, says, “We found a significant improvement in sperm parameters in the group that consumed the walnuts. The men who ate no tree nuts saw no change.”

Prof. Robbins, who was the lead author of the study, adds, “Women are not the only ones who should be paying attention to what they eat when they are trying to get pregnant.” Explaining the importance of the findings’ implications, she says, “This study shows that what men eat is important too.”

Although nutritionists have historically known that diet is directly related to fertility and have exploited that fact through the identification of many habits and nutrition practices for women’s reproduction, the UCLA says the nutrients and habits for men are less identifiable and, therefore, less clear. Researchers say this is particularly true for men with Western-style diets that may be lacking in important nutrients needed to develop healthy sperm.

Study co-author Catherine Carpenter, a professor at the UCLA Center for Human Nutrition and Schools of Nursing and Medicine, says, “Walnuts provide a particularly rich source of a-linolenic acid, a natural plant source of omega-3, which we suspect may have been responsible for the improvements we observed.” The researchers’ next step will be to work with infertile couples attending fertility clinics to determine whether or not men who eat walnuts have a better chance of successful conception.

Funding for this study was provided by a grant from the California Walnut Commission and the UCLA Fielding School of Public Health’s Center for Occupational and Environmental Health. Other authors of the study included Lin Xun, Leah FitzGerald, and Samantha Esguerra of the UCLA School of Nursing and Susanne Henning of the David Geffen School of Medicine at UCLA and their Center for Human Nutrition.