Pregnancy can be a stressful time. Now there’s a new stressor and it’s about stress itself.

A new study on pregnant mice, published in the journal Cell Metabolism, shows a causal link between prenatal stress and the onset of eating disorders — particularly binge eating disorder (BED) — later in life for the child.

The study, done by scientists at Israel’s Weizmann Institute of Science, also revealed good news: The researchers were able to prevent the onset of a compulsive eating disorder by feeding the mice a diet high in folic acid and B-vitamins.

Moderate exposure to stress during pregnancy is not all negative, according to the research team led by Prof. Alon Chen, head of the neurobiology department at the Weizmann. In fact, it makes good evolutionary sense, providing mothers with a way to communicate with their unborn offspring about the world into which they are about to emerge.

Stress, for example, can signal the embryo that it will be born into an area with poor food availability and that it should slow down its metabolic rate. The problem arises when a child with such “programming” is raised in a culture with an abundance of high-calorie foods – as is the case in much of the developed world today. The mismatch can lead to obesity.

Chen and his team stressed the mother mice while pregnant. When the babies were subsequently fed a high-calorie “Western” diet, they developed an impulse to binge eat.

Dr. Alon Chen from the Weizmann Institute of Science. Photo: courtesy

The researchers then looked into the young mice’s brains and found “large molecular differences between offspring whose mothers’ stress mechanism was activated and those in whose mothers it was not activated,” Chen said.

While the DNA in the mice did not change, the expression of their genome did. One of the most important mechanisms in epigenetics (literally: “on top of genetics”) is a biochemical process involving molecules in the methyl group that takes place in the hypothalamus, the brain region that regulates metabolic processes, hormone production and stress reactions.

“Perhaps the most unexpected finding in the study,” said Chen, “is that we succeeded in preventing the disorder from emerging simply by providing a balanced diet of methyl sources,” such as folic acid, choline, methionine, and vitamins B12 and B6.

“Does this mean that a balanced diet would also help cure eating disorders in humans? It is important to note that the research was conducted on a mouse model at this stage, but all the biological genes and pathways it described are shared by mice and humans.”

The main researcher was postdoctoral fellow Mariana Schroeder, with the participation of Maya Sharon Lebow, Yonat Drori, Mira Jakovcevski, Tamar Polacheck, Mareen Engel and Shifra Ben-Dor from the Weizmann’s Department of Life Sciences.