Warning: a father’s diet can mutate his sperm and lead to gene mutations in his children.

The results from two new mice studies demonstrated the many different ways a man’s lifestyle, including his dietary choices, could affect his offspring.

Both high-fat and low-protein diets affected certain small RNAs in the sperm, leading to changes in the offspring’s gene regulation and a host of metabolic conditions.

High-Fat, Low-Protein Diets

In the first study, a team led by Qi Chen of the University of Nevada School of Medicine fertilized mouse eggs with sperm from two male groups: those given a high-fat diet and those fed a normal diet.

While the two groups’ offspring showed no apparent difference in weight within a 16-week period, offspring from fathers in the high-fat-diet group developed impaired glucose sensitivity and insulin resistance as early as seven weeks, conditions that worsened at 15 weeks.

After further tests to see if sperm RNA contributed to such differences, the team purified RNAs from the two sperm groups and inserted them into normal zygotes, where the high-fat-diet kids had substantially higher glucose and insulin but comparable insulin sensitivity with normal-diet kids.

“These results suggest that RNAs from sperm of HFD males contain the information to induce glucose intolerance, but not insulin resistance,” concluded the authors in a news release.

tRNA fragments, which contain around 30 to 34 nucleotides, were identified as the group of small RNA that led to glucose intolerance in the high-fat-diet offspring, which also had significantly less gene expression involved in metabolizing ketones, carbohydrates, and monosaccharides.

In the second study, researchers led by Upasna Sharma investigated RNA changes in mice sperm caused by a low-protein diet.

The findings showed that while the diet did not affect small RNAs from immature sperm, it led to great expression of specific RNAs in mature sperm.

When the team isolated RNA in sperm from a group of mice fed a low-protein-diet mice and a control group, they found high levels of tRNA-Gly-GCC in the former, which suppresses a gene subset that includes one contributing to embryonic stem cell plasticity in mice.

Obesity Passed Down Through Dad’s Sperm?

A study from Danish researchers back in December discovered that fathers can transfer obesity heritable information to their offspring through their sperm. This study provided a genetic clue that may explain why children of overweight males tend to be overweight themselves.

Analyzing the sperm of 13 lean and 10 overweight males, the team found that epigenetic markers varied in the sperm of the overweight group, particularly those linked to brain function and development.

"Our research could lead to changing behavior, particularly pre-conception behavior of the father," said author Dr. Romain Barrès of the University of Copenhagen, who added that pregnancy advice and recommendations should also target men instead of just women.

Some experts lauded the research published in the journal Cell Metabolism, saying it is the first to indicate that men’s nutrition and lifestyle could also affect the future health and well-being of their children.

The team will be conducting a follow-up study of human embryos produced from sperm of men with different body weights.

Photo: Randen Pederson | Flickr