Nuts improve semen parameters in randomsised trial


Published 10 July 2018

Findings in healthy volunteers, and mainly explained by a reduction in sperm DNA fragmentation. Sophie Goodchild reports.

Eating 60 grams of mixed nuts a day as part of a regular diet significantly improves the quality and function of human sperm, according to a randomised trial presented at ESHRE's Annual Meeting in Barcelona.

Results from the study showed that men who ate walnuts, hazelnuts and almonds for 14 weeks had significant improvements in sperm count, vitality, motility, and some positive impact on morphology.

Presenting the findings, Dr Albert Salas-Huetos said the results support the potential benefits of some nutrients contained in tree nuts for sperm quality.

"Supplementation of a western-style diet with nuts improves the main sperm quality parameters among healthy reproductive-aged people," said Salas-Huetos from the Human Nutrition Unit at the Universitat Rovira i Virgil, in Spain.

"The beneficial effects could possibly be explained by a reduction in the sperm DNA fragmentation," he said. Pollution, smoking and western-style diets are some of the factors linked to a general decline in quantity and quality of human sperm in industrialised countries.

There is evidence that a healthy diet rich in omega-3 and phytochemicals may help improve the chances of conception, and nuts in general contain many of these nutrients.

The study set out to establish if a diet rich in nuts improved fertility in men by measuring conventional semen parameters and molecular changes over a 98-day period.

A total of 119 healthy men aged from 18 to 35 were recruited from the Catalonia region of Spain. Those randomised to the nut group (n=56) were allocated to their usual western-style diet supplemented with a 60 grams daily mix of raw almonds, hazelnuts and walnuts. The men in the control group (n=50) were also told to follow their usual western-style diet but without nuts.

Sperm and blood samples were analysed at baseline and after 14 weeks of intervention. Sperm parameters were recorded according to World Health Organisation (WHO) benchmarks - concentration (>15 million sperm cells per ml semen); progressive motility (>32%); vitality (>58%); and morphology (>4%). Changes in several molecular factors including sperm DNA fragmentation were also analysed.

The results showed that men randomised to the nut group scored significantly higher on semen quality parameters than those in the control group. The difference in improvement between those on nut supplementation and the control was more than 19% for sperm count; 4% sperm vitality; 6% sperm motility; and 1% in morphology.

In addition, those in the nut group showed a significant reduction in their levels of sperm DNA fragmentation.

However, Salas-Huetos emphasised that the subjects in the study were all healthy and apparently fertile men following a western-style diet, and warned that results cannot be extrapolated to the general population.

The findings are also not enough on their own, he added, to conclude that men who are hoping to conceive a baby should add nuts to their diet.

"We can't say that yet based solely on the results of this study," said Salas-Huetos.

"But evidence is accumulating in the literature that healthy lifestyle changes such as following a healthy dietary pattern might help conception- and of course, nuts are a key component of a Mediterranean healthy diet."