Page 62 - Today's Dietitian (March 2020)

Research Briefs

amounts in the sperm of many species,
including humans, fruit flies, and mice.
So far, their function hasn’t been exam-
ined in detail. Scientists have speculated
that the RNA fragments in sperm may be
involved in epigenetic phenomena, but
it’s too early to say whether this is the
case in humans. The researchers initiated
this new study to investigate whether a
high consumption of sugar affects the
RNA fragments in human sperm.
The study examined 15 healthy, 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 healthful eating
with one exception: During the second
week, the researchers added sugar, cor-
responding to around 3.5 L of sugar-
sweetened beverages, or 450 g of candy,
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 healthful diet), and
after the second week (when the par-
ticipants had additionally consumed
large amounts of sugar).
At the beginning of the study, one-
third of the participants had low sperm
Study Shows Link Between motility. Motility is one of several fac-
tors that influence sperm quality, and
Diet and Sperm Quality the fraction of people with low sperm
motility in the study corresponded
to that in the general population. The
S perm are influenced by diet, and factors, of which obesity and related that the sperm motility of all partici-
researchers were surprised to discover
diseases, such as type 2 diabetes, are
pants became normal during the study.
the effects occur rapidly. This
well known contributors. The research
is the conclusion of a study by
“The study shows that sperm motil-
researchers at Linköping Uni-
interested in epigenetic phenomena,
and seems to be closely coupled to diet.
versity in Sweden, in which group that conducted the new study is ity can be changed in a short period
healthy young men were fed a diet rich which involve physical properties or This has important clinical implica-
in sugar. The study, which is published levels of gene expression changing, even tions. But we can’t say whether it was
in PLOS Biology, gives new insight into when the genetic material isn’t changed. the sugar that caused the effect, since
the function of sperm and may in the In certain cases, such epigenetic it may be a component of the basic
long term contribute to new diagnostic changes can lead to properties being healthy diet that has a positive effect
methods to measure sperm quality. transferred from a parent to offspring on the sperm,” Öst says.
“We see that diet influences the motil- via the sperm or the egg. The researchers found that the small
ity of the sperm, and we can link the In a previous study, the scientists RNA fragments, which are linked to
changes to specific molecules in them. showed that male fruit flies that had sperm motility, also changed. They are
Our study has revealed rapid effects that consumed excess sugar shortly before now planning to continue the work and
are noticeable after one to two weeks,” mating more often produced offspring investigate whether there’s a link between
says Anita Öst, PhD, a senior lecturer in who became overweight. Similar studies male fertility and the RNA fragments in
the department of clinical and experi- on mice have suggested that small frag- sperm. They also will determine whether
mental medicine at Linköping Univer- ments of RNA, known as tsRNA, play a the RNA code can be used for new diag-
sity and head of the study. role in these epigenetic phenomena that nostic methods to measure sperm quality
Sperm quality can be harmed by appear in the next generation. These RNA during in vitro fertilization.
several environmental and lifestyle fragments are present in unusually large SOURCE: LINKÖPING UNIVERSITY

62 TODAY’S DIETITIAN • MARCH 2020