A group of researchers from Sweden have found that diets can produce rapid changes in sperm quality. The finding offers promise for new diagnostic methods for assessing sperm quality.
A variety of lifestyle and environmental factors can increase the likelihood of a reduction in sperm quality. Scientists know that obesity and disorders that are associated with it, most notably type 2 diabetes, can lead to this phenomenon.
In this new study published in PLOS Biology, researchers at Linköping University placed some young men on a high-sugar diet. They observed that this diet produced a rapid effect on their sperm quality.
“We see that diet influences the motility of the sperm, and we can link the changes to specific molecules in them,” said study lead Anita Ost, a senior lecturer at Linköping University’s Department of Clinical and Experimental Medicine. “Our study has revealed rapid effects that are noticeable after one to two weeks.”
The findings increase knowledge of sperm function and may lead to improved methods for evaluating sperm quality.
The principal aim of researchers in this study was to probe epigenetic phenomena. This is about changes in the levels of gene expression or physical properties when the DNA sequence remains unchanged.
These epigenetic changes result in the transfer of properties from parents to offspring through the sperm or the egg in some cases.
The research team wanted to find out whether the consumption of high amounts of sugar in diet could impact the sperm’s RNA fragments.
As shown in previous research, small RNA fragments referred to as tsRNA are involved in the appearance of epigenetic phenomena in offspring. They are present in high numbers in human sperm. The RNA fragments can also be found in the sperm of many other species, including fruit flies and mice.
Researchers found in one study that the consumption of high amounts of sugar by male fruit flies a little while prior to mating led to them often producing overweight offspring.
For now, scientists do not fully know the function of the RNA fragments. They, however, think that the fragments possibly play a role in epigenetic phenomena.
Diet and sperm motility
Researchers fed 15 young, non-smoking men a diet that was tailored according to the Nordic Nutrition Recommendations for healthy eating. The only adjustment they made to the recommendations was adding high amounts of sugar to the diet during the second week.
The quantity of added sugar was equivalent to 3.5 liters of carbonated drinks (or confectionery weighing 450 grams) daily.
The scientists assessed sperm quality and other health indicators of the subjects before starting the study. They repeated this after the first week and, again, after the second week.
The sperm motility of a third of the young men was low when the study started. This corresponded to the proportion of the general population with the issue.
Surprisingly, sperm motility became normal for all participants while the study was in progress.
Motility is one of the factors that affect sperm quality.
“The study shows that sperm motility can be changed in a short period, and seems to be closely coupled to diet,” Ost said. “This has important clinical implications.”
The researchers could not tell, however, whether the extra sugar added to the diet was responsible for this effect. Ost explained that the substance might be a vital part of a healthy diet that improves the quality of sperm.
In addition, the team observed a change in RNA fragments that are associated with sperm motility.
The next goal for Ost and her colleagues is to explore whether the small RNA fragments have a link to fertility in men. They also plan to study if the RNA can play a role in new diagnostic methods for sperm quality analysis in the future.