Food eaten during pregnancy can shape gut health long after birth. New research shows that certain food additives may influence gut bacteria passed from mother to baby.
A study in mice reveals that emulsifiers consumed by mothers can change early gut development in offspring.
Such early changes increase the risk of gut inflammation and weight gain later in life, even without direct exposure to additives.
The research, led by scientists from the Institut Pasteur and Inserm, highlights how early life nutrition can leave lasting biological marks across generations.
Food additives and gut bacteria
Emulsifiers help mix ingredients like oil and water. Food companies add these substances to improve texture and extend shelf life.
Processed foods often contain emulsifiers, including ice cream, baked goods, sauces, dairy items, and powdered baby formula.
Two common emulsifiers include carboxymethyl cellulose, also called E466, and polysorbate 80, known as E433.
Earlier studies already showed that these additives disturb gut bacteria in adults. The new work explores effects that begin before birth.
Gut bacteria play a central role in digestion, immune balance, and metabolism. Early life represents a sensitive window when gut microbes train immune cells to recognize friendly bacteria and avoid harmful reactions.
Effects of diet during pregnancy
Benoit Chassaing led the study as Inserm Research Director and Head of the Microbiome Host Interactions laboratory at the Institut Pasteur.
The experts gave female mice small amounts of E466 or E433 for ten weeks before pregnancy and during pregnancy and nursing. Their offspring never consumed emulsifiers directly.
Gut bacteria from the offspring showed clear changes during early life. Microbial composition shifted both in structure and function. Such changes faded later, yet long-term health effects remained.
A key finding involved flagellated bacteria. Such bacteria produce flagellin, a molecule that strongly activates immune sensors. Higher flagellin levels increased immune stimulation inside the gut.
Another change involved bacterial encroachment. Bacteria moved closer to the gut lining, reducing separation normally maintained by mucus and immune defenses. Such proximity increases immune stress during a critical growth phase.
Goblet cells and immune training
Goblet cells line the intestine and produce mucus. During early life, goblet cells also create temporary passages that allow small microbial fragments to reach immune cells. Scientists call these goblet cell associated antigen passages, or GAPs.
GAPs help immune cells learn tolerance toward friendly microbes. Proper timing matters. Premature closure blocks immune training and pushes immune balance toward inflammation.
In offspring born to mothers exposed to emulsifiers, key gut antigen pathways closed earlier than normal.
This early closure interfered with immune education during weaning, reducing tolerance signals while increasing inflammatory activity.
The researchers also found changes in immune cell balance. Lower regulatory immune cell numbers reduced control over inflammation.
Increased inflammatory signaling created a long lasting tendency toward immune overreaction.
Food additives raise health risks
Adult mice from emulsifier-exposed mothers showed higher risk of obesity when fed a high fat diet. Extra fat accumulation occurred even after gut bacteria composition appeared normal again.
Gut inflammation also increased. Exposure raised vulnerability to colitis, a disease marked by intestinal damage and immune cell infiltration. Early microbiota changes alone proved sufficient to trigger such outcomes.
Cross fostering experiments confirmed cause and effect. When newborns switched to unexposed mothers, early microbiota normalized and disease risk dropped. Such results show that early gut conditions drive later health.
The researchers also tested whether restoring GAP function could reverse damage. Chemical treatments that kept GAPs open during early life prevented inflammation and metabolic problems.
The results highlight a direct link between early immune education and adult disease risk.
Why human health research matters
Mouse studies cannot fully represent human biology. Still, findings raise concern because emulsifiers appear in many foods eaten during pregnancy and infancy.
Powdered baby formulas often contain such additives during a critical time for gut development.
“It is crucial for us to develop a better understanding of how what we eat can influence future generations’ health,” said study co-author Benoit Chassaing.
“These findings highlight how important it is to regulate the use of food additives, especially in powdered baby formulas, which often contain such additives and are consumed at a critical moment for microbiota establishment.”
“We want to continue this research with clinical trials to study mother-to-infant microbiota transmission, both in cases of maternal nutrition with or without food additives and in cases of infants directly exposed to these substances in baby formula.”
Future human studies will help clarify how diet during pregnancy shapes long-term gut health. Understanding early immune training may guide safer food choices for future generations.
The study is published in the journal Nature Communications.
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