Gut Microbiomes: Like Mother, Like Baby

New research suggests that high fiber in maternal diets improves the gut microbiomes of her and her children.

By Alexa Morales

Healthcare providers often recommend a balanced diet during their patient visits, especially those with expectant mothers. They usually say to eat lots of fruits and vegetables, for instance, but they don’t usually expand on the different health consequences of a “healthy diet” on both mothers and their babies. At the same time, media outlets and wellness companies’ marketing strategies cleverly promote various supplements, from multivitamins to pre- and probiotics. Though left unsaid, all this general advice and information points to the same influential factor in pregnancy outcomes: the microbiome. 

The microbiome is the collection of all microbes, such as bacteria and fungi, living in and on a person’s body. These microbial communities can be unique to each person and each body part. For example, the oral microbiome and the gut microbiome are markedly different. Despite these differences, the composition of each microbiome is essential to an individual’s health. 

It is not only important for expectant mothers to better understand the connection between their own diet and microbiome but also how these choices influence the development of their baby’s microbiome. The popular culture understanding of the gut microbiome and the impact of diet has blossomed of the last decade, but it often misses the nuanced importance in pregnancy. In particular, the process through which an infant acquires their microbiome begins at birth, as influenced by delivery method: Cesarean section or vaginal delivery. 

“The gut microbiome and its metabolites influence our central nervous system and are associated with mood disorders like depression and anxiety, so it is kind of the second brain, just in a different way,” says Erin Ferranti, PhD, a cardiometabolic researcher and professor at Emory University. 

There are many health implications from the interaction between maternal diet and the infant’s microbiome. A study published in Genome Medicine compared the effects of a high-fat maternal diet on the neonatal and infant gut microbiome in early life. The researchers found that the high-fat diets led to reduced microbial diversity in infants, as well as a relative depletion of healthy bacteria, like Bacteroides, in the infant gut microbiome both at birth and after six weeks of birth.  

Bacteroides are essential microbes, as they play a vital role in immune function and overall gut health from an early age. Notably, the depletion of Bacteroides may also influence an infant’s risk of developing obesity and other cardiometabolic complications. 

Other researchers have also had similar findings, especially in relation to the immune system. A recent study by researchers at Emory University, published in Mucosal Immunology, assessed the impact of dietary fiber intake on the intestinal microbiome and immune responses of mice. They found that fiber consumption can impact the development of immune cell populations, which are essential for intestinal health. Moreover, researchers also found negative intergenerational effects of a low-fiber diet on the offsprings’ intestinal microbiome and immune system.

“We have mice that eat a diet with a very low fiber content, and so these animals will not develop certain immune cell populations in the intestine,” says Luisa Cervantes-Barragan, PhD, researcher and professor of medicine at Emory University. “We can reverse the effect on the immune system if we give them the fiber, but if we do this over generations, the offspring will acquire a modified microbiome. It will not be enough to induce the development of the cells,” she adds. 

This can have greater consequences for lifelong health, as the kind of immune deficits Cervantes describes are permanent. The only way to fix it is to adequately supplement the diet to recover the microbes that were lost. 

Modifying an individual’s diet is not often easy, as it is a major behavioral shift. Therefore, focusing on a specific aspect, such as increasing fiber intake, can be crucial for improving both the mother’s and her baby’s health in the short- and long-term.

“Americans don’t get enough fiber, and we know that. We also know the associations between fiber and improved cardiovascular health, and with lower rates of colon cancer,” says Ferranti. 

The recommended fiber intake is around 25 to 30 grams per day, but the average fiber intake of most Americans is around 8 to 10 grams. This does not only contribute to less diverse mother and infant microbiomes, but it is also linked to the obesity epidemic and to overall poor cardiovascular health plaguing the America health landscape.

An article published in Microbiome suggests that even small changes can have meaningful impacts on babies’ microbiomes. The study found that improving consumption of fruit — which is a good source of fiber — in expectant mothers was associated with increased abundance of healthy bacteria, such as Bifidobacterium, Streptococcus, and Clostridium, in vaginally delivered babies. Still, there remains much uncertainty around why this is. 

“We know what ‘healthy diets’ are, but we don’t know the mechanisms by which they are protective,” Ferranti says.

Science continues to uncover profound connections between maternal health and infant development, but one message is becoming increasingly clear: what mothers eat during pregnancy and postpartum matters; not just for their own wellbeing, but for the lifelong health of their children. A high-fiber diet, for one, does not only support digestion and reduce chronic disease risk in the mother—it also fosters a diverse and resilient microbial environment in their infants. 

Public health education efforts must shift to promote fiber as a central component of prenatal nutrition. It is imperative to encourage expectant mothers to focus on overall diet quality and the small but powerful dietary changes they can make, such as adding more fruits, vegetables, legumes, and whole grains to their plates. The benefits begin early on, even before birth, but they can ripple far into the future.