Recent research in animals has shed light on how some common food emulsifiers during pregnancy can alter a newborn’s gut microbiome in the first few weeks of life. But what does that mean for us?
Content Outline
We’ve all heard the phrase, “you are what you eat”, but is there really any truth in it? It seems there may be, and perhaps what your mother eats while carrying you during pregnancy could also influence your health for the rest of your life.
Recent research in mice has found that what a mother consumes during pregnancy can have far-reaching consequences for her child’s health well beyond infancy. Here, we explore the study's findings and their potential impact on humans.
Can A Mother’s Diet Really Affect Her Infant?
Researchers from the Institut Pasteur and Inserm have found that consuming common dietary emulsifiers before, during, and after pregnancy while breastfeeding can alter the composition of the child’s gut microbiome in the first few weeks of life, even though the infant has not directly consumed the emulsifiers themselves.
What Are Dietary Emulsifiers?
Dietary emulsifiers are additives or ingredients that are added to many foods, including mayonnaise, bread, cakes, and ice cream. They work by attracting water and oil in foods to help improve texture, consistency, and appearance. For example, in mayonnaise, the presence of emulsifiers stops the sauce from separating into layers of oil and vinegar, which wouldn’t be particularly appetitizing.
Emulsifiers can be natural, so they are made from plants or animal parts, or synthetic, which are man-made but have similar structures to natural ones. It’s hard to quantify how much we consume in our daily diet because we all have different diets and eat different amounts, but some research shows that in Europe, many people, including children, exceed the acceptable daily intake (ADI) of emulsifiers.
What Emulsifiers Were Used In This Study?
In this study, led by Benoit Chassaing, female mice were fed two common emulsifiers called:
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carboxymethyl cellulose (CMC/E466)
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polysorbate 80 (P80/E433)
They were fed them starting 10 weeks before getting pregnant, throughout pregnancy, and during breastfeeding. The researchers then analysed the gut microbiomes of infants born to mothers who had not directly consumed the emulsifiers.
What did the results say?
After analysing the gut microbiota of infant mice, the scientists found noticeable changes in their gut bacteria during the first few weeks of life. That’s because mothers naturally pass some of their microbiota to their children through close contact. These changes in the gut microbiome could have lasting consequences.
Dysregulated Gut-Immune Communication
The altered gut microbiota in the infants contained high levels of flagellated bacteria, which are known to activate the immune system and promote inflammation. Alongside this, a higher proportion of bacteria were found to penetrate the intestinal mucosal lining, a process known as bacterial “encroachment”, which contributes to gut-inflammation and the development of chronic conditions, such as type 2 diabetes and inflammatory bowel disease (IBD).
This led to a premature closure of the goblet cells associated passage (GAPs). These are an important pathway that allows small bacterial fragments to cross over the gut barrier, enabling the body’s immune system to recognize them and help it understand that the microbes are harmless.
In the infants of mice exposed to emulsifiers, premature closure of GAPs led to dysregulated communication between the gut and the immune system, with lasting consequences. Not least because once the infant mice reached adulthood, this disruption resulted in an overactive immune response, increased inflammation, and increasing the risk of metabolic disease, including obesity (Fig. 1), and inflammatory bowel disease.
Figure 1. Infants of mice fed CMC and P80 emulsifiers gained more weight than those fed only water. However, those who were cross-fostered with water-fed mice had a normalized gut microbiota composition, sufficient to prevent obesity in adulthood.
What This Means For Humans
The research was conducted in mice, but the findings could have important consequences for humans, especially during pregnancy and early life, which are critical periods for gut microbiome development.
Importantly, what we eat could influence the health of future generations. This is particularly relevant as the regulation of additives, like emulsifiers, is not properly regulated, and with the rise in ultra-processed foods and baby formula, this could have detrimental implications for the developing microbiota and the future health of the host. In this study, mice exposed to emulsifiers via their mothers were susceptible to metabolic and inflammatory illnesses, suggesting the same may occur in humans.
Dietary emulsifiers have been shown in earlier studies to disrupt the gut microbiota, contributing to dysbiosis. In humans, the same emulsifiers that were used in the current study severely impacted the gut microbiota, promoting the growth of pathogens and inflammation-causing flagellated bacteria. Some types of emulsifiers have also been shown to reduce butyrate production by as much as 96%. This could have a detrimental impact on gut health because butyrate is the main energy source for the cells that line the gut and help to maintain the strength and integrity of the intestinal lining. Although no significant bacterial shifts were noted with CMC or P80.
Future Perspectives
A key way to keep your gut microbiome balanced is to keep track of the foods you eat that could contain dietary emulsifiers. This can be challenging, but food manufacturers are legally required to list all emulsifiers used as ingredients on the food label.
Eating a healthy, balanced diet that is rich in prebiotic fiber, like that found in fruits, vegetables, and wholegrains, is a great way to keep your microbiota balanced. Human milk oligosaccharides (HMOs) are a type of prebiotic that naturally reside in human breast milk, and are critical for the normal development of the infant gut microbiome and immune system. Yet, emerging research is demonstrating that HMOs can have important roles in adult health, both in the gut and beyond.
⏵Interested in HMO supplements? Check out our range for both adults and children.
Summary
A new mouse study suggests that a mother’s diet during pregnancy and breastfeeding could influence her child’s long-term health — even if the infant never consumes the additives directly. Researchers found that common dietary emulsifiers used in many everyday foods, including carboxymethyl cellulose (E466) and polysorbate 80 (E433), altered the gut microbiome of newborn mice in the first weeks of life. Because mothers naturally transfer microbes to their offspring through close contact, changes to the mother’s microbiota can shape the infant’s early microbial “starter kit.”
In the study, infant mice exposed indirectly to emulsifiers showed increases in inflammation-linked, flagellated bacteria and greater “bacterial encroachment” into the gut’s protective mucus layer. These shifts disrupted normal gut–immune communication, including premature closure of key immune-training pathways, which appeared to leave lasting effects. By adulthood, the offspring were more prone to exaggerated immune responses, higher inflammation, and increased susceptibility to metabolic and inflammatory diseases such as obesity and inflammatory bowel disease.
While these findings come from animal research and can’t be applied one-to-one to humans, they reinforce how crucial early life is for microbiome development — and how modern ultra-processed diets may play a role. Want to support a healthier gut ecosystem for the whole family? Explore our science-led range of HMO supplements for adults and children and take a simple step toward microbiome resilience today.
Written by: Leanne Edermaniger, M.Sc. Leanne is a professional science writer who specializes in human health and enjoys writing about all things related to the gut microbiome.
