Sperm Quality Has Been Declining And Diet May Be To Blame

Two new studies show how dad's lifestyle affects sperm quality.

07/01/2016 1:26 AM AEDT | Updated 07/01/2016 1:30 AM AEDT
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The researchers expect the results of their experiments, which were conducted on mice, to be replicated in humans.

Most conversations about infertility and healthy reproduction tend to focus on the woman, and how things like age, environment and lifestyle factors can affect her ability to give birth to a healthy baby.

But new research is suggesting that the health of the father may play a more significant role that has traditionally been thought. Two new studies, published independently in the journal Science, showed that a father's diet can powerfully affect his offspring.

In one of the studies, a team of Chinese researchers fed male mice a high-fat diet and then harvested their sperm to impregnate female mice. The offspring of those mice developed impaired insulin resistance and glucose intolerance -- both known precursors to diabetes -- while the offspring of a control group of mice did not. 

A second study conducted by U.S. and Canadian researchers, which ran the same experiment but with a low-protein diet, was less conclusive. The only changes to offspring that the researchers observed were some alterations in genes responsible for stem cell development. 

The findings suggest that the DNA contained in sperm isn't the only impact a father has on his offspring. RNA -- a chain of acids whose job is to help carry out the "blueprint" contained in DNA  -- may also play a role. In the Chinese experiment, transfer RNAs seemed to carry the information from the father's diet that later impacted the offspring's health. 

"Traditionally, the male contribution to a child has been thought to be limited to one half of the child’s DNA," Dr. Oliver Rando, a biochemist at the University of Massachusetts Medical School and one of the study's authors, told The Huffington Post. "So this general idea that a father’s diet or environment can influence his children’s metabolism or other traits obviously challenges this way of thinking."

New research also suggests that a prospective father's diet may affect his fertility. Another recent study found environment and lifestyle factors -- including diet and exercise -- to be strongly linked to male reproductive health and infertility, potentially playing a role in decreasing birthrates globally. 

“I was surprised that we found such poor semen quality among young men ages 20 to 25,” the lead author of that study, Dr. Niels Skakkebaek of the University of Copenhagen, said in a statement. “We found that the average man had more than 90 percent abnormal sperm. ... It appears that we are at a tipping point in industrialized countries where poor semen quality is so widespread that we must suspect that it results in low pregnancy rates.”

Skakkebaek and his colleagues concluded that the advancing age of prospective mothers isn't the only important biological factor in declining pregnancy rates. "The situation is more complex," he said. 

The authors of the studies on mice suggest that if the results are replicated in humans, as they are expected to be, then it may be wise for prospective mothers and fathers to consider their diets leading up to pregnancy. 

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