Mothers Can Pass Obesity to Offspring Through Mitochondrial DNA in Eggs, Study Finds

Obesity and metabolic disorders in a woman can be passed to future generations, even if a child is fed a healthy diet, and — at least in mice, the subjects of this study — may be a predetermined outcome even before the offspring are conceived. The study, “Maternal Metabolic Syndrome Programs Mitochondrial Dysfunction via Germline Changes across Three Generations,” was published in the journal Cell Reports.

Scientists already know that maternal obesity significantly affects a child’s health, but not the mechanisms behind this association, leading a group of scientists at Washington University School of Medicine in St. Louis to study how maternal obesity influences a child’s weight later in life.

To this end, researchers fed female mice a high-fat/high-sugar diet (60% fat and 20% sugar), starting at six weeks prior to conception and continuing until weaning.

“This mimics more of the Western diet. Basically, it’s like eating fast food every day,” Kelle H. Moley, MD, the James P. Crane Professor of Obstetrics and Gynecology at the school and the study’s lead author, said in a press release.

Investigators then assessed the outcomes of this diet in the mice offspring, following the next three generations, all fed a healthy control diet (high in protein, and low in fat and sugar).

They found that despite good diets, the offspring developed insulin resistance and other metabolic problems. The team also discovered that a mother’s obesity — and its associated metabolic disorders — is passed to her offspring via the mitochondria DNA that is present in the mother’s sex cells, i.e., the still unfertilized eggs. (Mitochondria are small organelles inside our cells and they are considered the cells’ powerhouses, since it is here that the energy for the body is produced. Mitochondria contain their own DNA, which is transmitted only by females to their offspring.)

“It’s important to note that in humans, in which the diets of children closely mirror those of their parents, the effects of maternal metabolic syndrome may be greater than in our mouse model,” Dr. Moley said. “Our findings indicate that a mother’s obesity can impair the health of later generations. This is particularly important because more than two-thirds of reproductive-age women in the United States are overweight or obese.”

She concluded: “In any case, eating nutritiously is critical. Over the decades, our diets have worsened, in large part due to processed foods and fast foods. We’re seeing the effects in the current obesity crisis. Research, including this study, points to poor maternal nutrition and a predisposition to obesity.”