Just two handfuls of nuts per day can boost sperm quality, new Australian research shows.
Shoving a few handfuls of nuts into your mouth each morning might be key to improving your swimmers, according to new research out of Monash University.
A new systematic review published in Advances in Nutrition this month struggled to find a large body of high-quality research on the topic, eventually settling on just two randomised control trials to include in its meta-analysis.
Put together, the two randomised control trials involved 223 healthy males between 18 and 35 who ate around two servings of nuts per day for about three months.
Participants in one study received 75g of shelled English walnuts per day and participants in the second study received 30g walnuts, 15g almonds and 15g hazelnuts.
All men ate a Western-style diet. In both studies, the control group continued to eat a regular diet without nuts.
At the end of three months, the nut cohort in both studies showed improvement in their semen motility, morphology and vitality, although there was no difference in sperm concentration.
The working hypothesis was that, because nuts are highly concentrated in alpha-linolenic acids and monounsaturated fatty acids, they were able to positively regulate the fatty acid concentrations in the sperm membrane, enhancing the anti-inflammatory pathway and increasing the antioxidant capacity.
“Higher concentration of antioxidants in the follicular fluid correlates with production of high-quality oocytes, which ultimately contributes to successful embryo development,” the researchers wrote.
“During spermatogenesis, the developing sperm cells are highly sensitive to oxidative stress in seminal fluid, thus the higher concentration of antioxidants reduces sperm DNA fragmentation.”
Future studies could interrogate different combinations of nuts, the researchers said.
For example, tree nuts – e.g. almonds, brazil nuts, cashews, hazelnuts and walnuts – have an “optimal fatty acid profile”.
While the finding in the meta-analysis was promising, two other observational studies – included in the review but not in the meta-analysis – did not find any significant associations between nut consumption and fertility.
This may have been because the observational study populations had low nut consumption, the researchers wrote.
“The statistical analysis in both studies was adjusted for other factors such as physical activity,” lead author Dr Barbara Cardoso said.
“The findings show that this simple strategy has positive effects regardless of other lifestyles.”
Dr Cardoso, a researcher at Monash University’s department of nutrition, dietetics and food said the next logical step in the research was to study the effects of nuts on female fertility.
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