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Fat in an Expectant Mother's Diet May Shape Baby's Gut Microbiome

To equip an unborn baby with a healthy gut microbiome, new research suggests that mama might want to pass on the fries.
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(Photo: yourdon/Flickr)

(Photo: yourdon/Flickr)

To fully judge the health of an infant, you would need to peer deep inside its tubby little belly. A naturally balanced ecosystem of gut microbes could help the child avoid a life of chronic gastroenteric diseases and obesity—perhaps even reduce its risks of developing asthma, anxiety, and allergies.

And when it comes to equipping a developing fetus with a healthy gut microbiome, scientists are discovering that a lean maternal diet could be key.

We wrote last week about new research that revealed similarities between placental and oral microbiomes, which scientists suspect may have something to do with early feeding of unborn babies. Several of the scientists behind that Science Translational Medicine paper contributed to another study, published recently in Nature Communications, that uncovered links between the fat content of expectant and lactating monkey mothers' diets and the gut microbiomes of their young.

When it comes to equipping a developing fetus with a healthy gut microbiome, scientists are discovering that a lean maternal diet could be key.

Obesity isn't just linked to diet. There are close links between obesity and gut microbial ecosystems, and between diet and gut microbes. More than 90 percent of the human gut microbiome is made up of two phyla of bacteria—Bacteroidetes and Firmicutes. The stomachs of obese individuals tend to harbor more Firmicutes and less Bacteroidetes than do others. Switching to a lean diet helps boost Bacteroidetes levels while also shedding pounds. And in rodents, transplanting gut bacteria from obese to lean animals has been shown to cause the once-lean rodents to quickly gain weight.

The researchers were interested to know whether the BMI or diet of a mother had a more profound effect on the gut microbiome of her young. So they fed pregnant and lactating Japanese macaques diets that contained 36 percent fat—typical of calorie-dense Western human diets. They fed others on diets containing more natural fat levels of 13 percent. Some of the baby monkeys were fed the same diets as their mothers; others were weaned onto the alternative. Some of the mother monkeys were obese before the experiments began; others were not.

The scientists discovered that limiting fat intake during pregnancy had a profound and positive effect on the gut microbiomes of the mother and her young. It was actually far more important for fostering healthy gut microbiomes than whether or not the mother was obese.

Because of similarities between Japanese macaque and human microbiomes, the scientists think the findings have ramifications for human health.

"Based upon the data, we show that it doesn’t matter whether [animal mothers] are lean or obese," says Kjersti Aagaard, an associate professor at the Baylor College of Medicine.

The most unhealthy microbial imbalances were found in young that were weaned on high-fat diets after developing in the wombs of mothers fed on high-fat diets. Switching to a lean diet during weaning helped correct the imbalance, but not entirely.