Diet Rapidly Affects Sperm Quality

In a study published yesterday in PLOS Biology, Linköping University researchers show that human sperm are affected by diet—and the effects arise rapidly. The study gives new insight into the function of sperm and may, in the long term, contribute to new diagnostic methods to measure sperm quality.

“We see that diet influences the motility of the sperm, and we can link the changes to specific molecules in them,” says senior author Anita Öst. “Our study has revealed rapid effects that are noticeable after one to two weeks.”

Several environmental and lifestyle factors affect sperm quality—obesity and related diseases, such as type 2 diabetes, being well-known examples. Because of this, the researchers were interested in epigenetic phenomena, which cause changes in gene expression without altering the DNA sequence.

In a previous study, the scientists showed that male fruit flies that had consumed excess sugar shortly before mating were more likely to produce offspring who became overweight. The new study investigated the effect of high sugar consumption in human sperm.

The study examined 15 healthy, non-smoking young men whose diet was completely controlled by scientists for two weeks. The diet was based on the Nordic Nutrition Recommendations for healthy eating with one exception: during the second week, the researchers added excess sugar—corresponding to around 3.5 liters of fizzy drinks—every day. The sperm quality and other indicators of the participants’ health were investigated at the start of the study, after the first week, and after the second week.

At the beginning of the study, one-third of the participants had low sperm motility (which corresponds to the levels in the general population). But 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,” Öst says. “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 healthy diet that has a positive effect on the sperm.”