What is already known
The major determinants of microbiota composition are diet, in particular its fiber content, and the type of microbes acquired early in life. Bacteria are transferred from a mother to her offspring during vaginal birth and breastfeeding, but the effects of a nursing mother’s diet on the offspring remain unclear.
What this research adds
Researchers fed nursing mice a traditional, fiber-balanced diet or a low-fiber diet and then analyzed the pups’ microbiota. Compared to pups nursed by mothers fed a traditional diet, those nursed by mothers on low-fiber diets had altered gut microbiotas with high levels of Proteobacteria and low microbial diversity. These animals also showed signs of gut inflammation, and the pups rapidly gained weight and body fat when exposed to a high-fat diet.
Conclusions
The findings suggest that a mother’s diet during nursing influences her offspring’s microbiota composition, gut health and predisposition to become obese.
Most babies acquire their first gut microbes during birth and through breastfeeding. Now, a study done in mice shows that pups nursed by a mother on a low-fiber diet experience microbiota alterations that can lead to gut inflammation and obesity.
The findings, published in Cell Host & Microbe, suggest that a mother’s diet during nursing influences her offspring’s microbiota composition, gut health and predisposition to become obese. “I hope this work can shed light onto how complex our metabolism and microbiome really are and how our early life experiences can shape us for the rest of our lives,” says study lead author Andrew Gewirtz at Georgia State University.
The major determinants of microbiota composition are diet, in particular its fiber content, and the type of microbes acquired early in life. To investigate the effects of a nursing mother’s diet on her offspring, Gewirtz and his team fed nursing mice a traditional, fiber-balanced diet or a low-fiber diet. Then, the researchers analyzed the pups’ gut microbiotas.
Gut disruptions
After three weeks, pups nursed by mothers on low-fiber diets had altered gut microbiotas compared to those nursed by mothers fed a traditional diet. The alterations included high levels of Proteobacteria and low microbial diversity.
Both mothers on a low-fiber diet and their pups showed signs of gut inflammation, the researchers found. That’s likely because some surface proteins of Proteobacteria can trigger inflammatory signaling in the body. The bacteria also alter the gut in ways that favor the uptake of fatty molecules from the diet, the authors say.
When exposed to a high-fat diet, pups nursed by mothers on low-fiber diets doubled their weight and rapidly accumulated body fat. “I was shocked at how quickly the mice gained weight when they were exposed to this diet,” Gewirtz says.
Long- lasting effects
Pups nursed by mothers on low-fiber diets experienced long-lasting alterations of their gut microbiotas. After being on a traditional diet for nine weeks following weaning, the pups continued to gain weight and to have increased levels of Proteobacteria in their guts.
The researchers speculate that dietary fiber allows diverse bacteria to thrive in the gut. But when dietary fiber is no longer available, bacteria that use it as fuel die off, whereas those that don’t use it — such as Proteobacteria — can grow unchecked.
Although mice and humans have different nutritional requirements, which makes the generalization of mouse dietary studies limited, the findings suggest that the acquisition of the first gut microbes can influence one’s susceptibility to obesity.
