are influenced by diet
, and the effects arise rapidly
. 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, 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
Dr Anita Öst, senior lecturer in the Department of Clinical and Experimental Medicine at Linköping University, and head of the study told Thailand Medical
News, “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.”
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. The research group that carried out the new study is interested in epigenetic
phenomena, which involve physical properties or levels of gene expression changing, even when the genetic material, the DNA sequence, is not changed. In certain cases such epigenetic
changes can lead to properties being transferred from a parent to offspring via the sperm
or the egg.
In past studies, the scientists showed that male fruit flies which had consumed excess sugar shortly before mating more often produced offspring who became overweight. Similar studies on mice have suggested that small fragments of RNA known as tsRNA play a role in these epigenetic
phenomena that appear in the next generation. These RNA fragments are present in unusually large amounts in the sperm
of many species, including humans, fruit flies and mice. So far, their function has not been examined in detail. Scientists have speculated that the RNA fragments in sperm
may be involved in epigenetic
phenomena, but it is too early to say whether this is the case in humans. The new study was initiated by the researchers to investigate whether a high consumption of sugar affects the RNA fragments in human sperm
The recent study examined 15 normal, non-smoking young men, who followed a diet
in which they were given all food from the 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 sugar, corresponding to around 3.5 liters of fizzy drinks, or 450 grams of confectionery, every day. 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)
ng>, and after the second week (when the participants had additionally consumed large amounts of sugar).
One third of the participants had low sperm motility at the beginning of the study. Motility is one of several factors that influence sperm quality, and the fraction of people with low sperm motility in the study corresponded to that in the general population. The researchers were surprised to discover that the sperm motility of all participants became normal during the study.
Dr Anita Öst added, “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.”
The medical researchers also found that the small RNA fragments, which are linked to sperm motility, also changed. 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 fertilization.
Reference: “Human Sperm Displays Rapid Responses to Diet” by Daniel Nätt, Unn Kugelberg, Eduard Casas, Elizabeth Nedstrand, Stefan Zalavary, Pontus Henriksson, Carola Nijm, Julia Jäderquist, Johanna Sandborg, Eva Flinke, Rashmi Ramesh, Lovisa Örkenby, Filip Appelkvist, Thomas Lingg, Nicola Guzzi, Cristian Bellodi, Marie Löf, Tanya Vavouri, Anita Öst, PLOS Biology. DOI: 10.1371/journal.pbio.3000559