Nuts are rich in omega-3, antioxidants, and folate.
The findings were presented at the annual meeting of the European Society of Human Reproduction and Embryology (Eshre) taking place in Barcelona, Spain. The study lasted for almost four months (14 weeks), after which the researchers compared the sperm quality of both groups. The researchers write that there has been a decline in male sperm quality of late attributed to "pollution, smoking, and trends toward a western-style diet". The men were randomized into two groups, one continuing on their usual western-style diet with no nuts, and the other group supplementing that normal diet with 60 grams a day of an almond/hazelnut/walnut mix.
Researchers say the findings "support a beneficial role for chronic nut consumption in sperm quality" and reflect the value of further male-specific dietary recommendations. Indeed, it was this change in the level of DNA fragmentation in the sperm cells by which the investigators explained, at least in part, the improvement in sperm count, motility and morphology.
Nuts contain many of these and other nutrients.
Sperm and blood samples were analysed at baseline and after 14 weeks of intervention.
Sperm counts have halved in the western world over the past four decades, which, alongside rising testicular tumours, could be behind plummeting fertility rates and couples' increasing dependency on IVF, according to Professor Niels Skakkebaek from the University of Copenhagen.
In the study, subjects randomised to the nut group had significant improvements in their sperm count, vitality, motility and morphology (shape), researchers said. They also had reduced DNA fragmentation, which is a measure of sperm damage.
The Spanish authors said the study results were not on their own enough to justify urging men to eat nuts if they want to conceive.
The results of this new study confirm previous research carried out in 2013 by the researchers from the Fielding School of Public Health at UCLA University in California, USA, which also revealed that a considerable quantity of nuts, consumed daily, would improve the sperm quality and male fertility, in general.
Any nut would be useful in the prevention of male infertility. In a press release, he stresses that the results may not necessarily apply to the general population, since all of the study participants were healthy and fertile.