OKLAHOMA CITY — A recently published study involving pregnant women with gestational diabetes mellitus demonstrates the importance of the mother’s diet in changing the microbiome and decreasing the risk of her baby becoming obese and developing conditions like diabetes. The study, published in the journal Frontiers in Endocrinology, was led by Jed Friedman, Ph.D., director of OU Health Harold Hamm Diabetes Center at the University of Oklahoma Health Sciences Center.

Like other types of diabetes, gestational diabetes mellitus (GDM) occurs when the body cannot make enough insulin. GDM affects 1 in 10 pregnant women in the United States and is typically diagnosed late in the second trimester of pregnancy. For women, GDM increases the risk that they will develop Type 2 diabetes and coexisting conditions after pregnancy. In newborns, GDM may lead to poor health and increase their risk later in life for metabolic disorders such as diabetes as well as heart disease. GDM has been increasing in recent years because of the obesity epidemic, older pregnancy age, and metabolic syndrome in pregnant women.

When a woman has GDM, her gut microbiome, as well as that of her baby, are negatively affected. The microbiome, which features trillions of microorganisms in the intestinal tract, influences numerous functions that are essential to overall health.

“The infants of women with GDM are more likely to develop obesity and have a higher risk for inflammation and different kinds of metabolic diseases, including diabetes,” Friedman said. “We wanted to see if we could decrease that risk through the mother’s microbiome by changing her diet while she is pregnant.”

In a randomized, controlled trial, half of the participants were provided the CHOICE diet (Choosing Healthy Options in Carbohydrate Energy) when they were diagnosed with GDM. The CHOICE diet featured 60% complex carbohydrates, 25% fat and 15% protein. The control group was provided a more conventional diet that had 40% complex carbohydrates, 45% fat and 15% protein. Study participants received all meals, delivered to their homes, so that their diets were consistent from the time of diagnosis until delivery.

Researchers studied stool samples and bloodwork from the women during pregnancy and in their infants for four months after they were born. They discovered that the CHOICE diet — containing greater complex carbohydrates and reduced fat — not only benefited the mother’s microbiome during pregnancy, but improved the “good” bacteria in the baby’s microbiome, and reduced the number of “bad” bacteria that play a role in the development of obesity and increase the risk for metabolic disease.

In particular, women on the CHOICE diet had higher levels of a beneficial microorganism called Bifidobacterium adolescentis as compared to women on the conventional diet. This species of bacteria is typically suppressed in women with GDM.

“We think this bacteria took advantage of the higher complex carbohydrates in the diet of women on the CHOICE diet to make the gut much healthier,” Friedman said. “For the babies, we don’t yet know if their improved microbiome profile will benefit them in the long term, but we have evidence from this study and others that the consequences on metabolism may be significant.”

The study not only underscores the importance of a healthy diet for pregnant women and the future development of their babies, but it provides further evidence that modifications to the microbiome can significantly impact future health. Understanding how the maternal and early life infant microbiome interacts with lifestyle and environment is one of the most important aspects of this study.

Studies of the microbiome are a major part of the research focus at Harold Hamm Diabetes Center. One of the center’s three pathways toward a cure for diabetes is the “first 1,000 days” — from conception to a child’s second year of life. During that time, there are critical windows of development, like that of the microbiome, that affect a person’s health across the life span.

“GDM passes along a greater risk for obesity and diabetes to the next generation, but if we know which microbes are involved in that risk, we might be able to make improvements that benefit the infant’s metabolism and decrease their chance of developing obesity,” Friedman said. “Pre-pregnancy weight loss and lifestyle modifications are our main targets to try to mitigate the risks. Now that we know the microbiome is disrupted and that nutrition during pregnancy can reverse this, that’s a real target for us scientifically and therapeutically.”

Friedman began the study while he was at the University of Colorado and completed it after moving to Oklahoma, in collaboration with his University of Colorado colleagues. While the study was small, it sets the stage for additional research into the effects of highly controlled diets on the microbiomes of women with gestational diabetes as well as their infants.