Diet can influence sperm quality after just a few weeks. This is the conclusion of a study by researchers at Linköping University, in which healthy young men were fed a diet rich in sugar.
The study reinforces the link between nutrition and male reproduction and could have important implications for those undergoing fertility treatment. The study, which has been published in PLOS Biology, gives new insight into the function of sperm, and may in the long term contribute to new diagnostic methods to measure sperm quality.
Sperm quality can be harmed by several environmental and lifestyle factors, of which obesity and related diseases, such as type 2 diabetes, are well-known risk factors for poor sperm quality.
“We see that diet influences the motility of the sperm, and we can link the changes to specific molecules in them. Our study has revealed rapid effects that are noticeable after one to two weeks”, says Anita Öst, senior lecturer in the Department of Clinical and Experimental Medicine at Linköping University, and head of the study.
In the study, 15 non-smoking men aged 20-27 followed a specific diet for two weeks. In the first week they ate a healthy diet as recommended by the Nordic Nutrition Recommendations. During the second week, the men ate an extra 375g of sugar per day, which is equivalent to about 3.5 litres of sugary drinks or 450 grammes of confectionery.
The sperm quality and other indicators of the participants’ health were investigated at the start of the study, after the first week (during which they ate a healthy diet), and after the second week (when the participants had additionally consumed large amounts of sugar).
At the beginning of the study, one third of the men had low sperm motility. Motility is one of several factors that influence sperm quality. The researchers were surprised to discover that the sperm motility of all participants became normal during the study.
“The study shows that sperm motility can be changed in a short period, and seems to be closely coupled to diet. This has important clinical implications. But we can’t say whether it was the sugar that caused the effect, since it may be a component of the basic healthly diet that has a positive effect on the sperm”, says Anita Öst.
The researchers found that the small RNA fragments, which are linked to sperm motility, also changed. Τhey discovered that tsRNA levels were increased in some of the men after they had eaten a high sugar diet for a week.
They are now planning to continue the work and investigate whether there is a link between male fertility and the RNA fragments in sperm. They will also determine whether the RNA code can be used for new diagnostic methods to measure sperm quality during in vitro fertilisation (IVF).