In industrialized countries, infertility and subfertility among men caused by poor semen quality have been inked to unhealthy lifestyles, pollution, and the Western-style diet. But a new study, published in the online journal Biology of Reproduction, found that daily consumption of walnuts can boost the structure, vitality and motility of healthy, young men’s sperm.
The researchers worked on the hypothesis that adding 75 grams of whole-shelled walnuts to the daily, Western-style diet of healthy men in their 20s and 30s would improve the quality of their sperm. The amount of walnuts they used in the study was equivalent to the typical amount of walnut snacks sold in supermarkets. Additionally, the researchers determined that 75 grams was enough to affect blood lipid levels without increasing weight.
Lead researcher Wendie Robbins, of the University of California, Los Angeles (UCLA) and her team divided 117 healthy, young men,
between 21 and 35 years, who they enrolled in the 12-week study into two groups: one group ate 75grams of walnuts a day and the other group were asked not to consume tree nuts.
Walnuts are known to be loaded with polyunsaturated fatty acids (PUFAs), the same healthy fats found in fish, fish oils, and flaxseeds. PUFAs are important in healthy sperm maturity and in preserving the sperm cell’s membrane’s integrity, both of which boost sperm quality and the sperm’s ability to fertilize an egg.
At the end of the 12-week period, the sperm samples collected from the participants were compared to samples taken before the start of the study; the researchers assessed the each sample’s sperm concentration, morphology, motility, vitality, and chromosome abnormalities. The participants also gave blood samples before and after the study and these were tested for lipid levels.
The findings revealed that the group which consumed walnuts daily had higher levels of omega-3 and omega-6 fatty acids in their blood at the end of the study than they did before the study began. The sperm samples of the men in the walnut group also showed better morphology, motility, and vitality, as well as fewer chromosome abnormalities compared to the sperm samples taken at the start of the study. On the other hand, there were no changes observed in the blood and sperm samples of the men in the second group.
The researchers concluded that adding walnuts daily to the Western-style diet of healthy, young men can improve the quality of their sperm. They also pointed out, however, that these results do not show a direct link between eating walnuts and increased fertility and the findings may also not be the same for men who already have fertility problems.