Scientists have discovered that the food a mother eats during pregnancy and while breastfeeding can influence whether her child develops food allergies. This happens through the mother’s gut bacteria, which produce special chemicals that help train the baby’s immune system. After birth, eating lots of processed foods can damage this protection by changing the gut bacteria in unhealthy ways. This review brings together research from around the world to explain how diet shapes our immune system’s ability to tolerate different foods, from before birth through the teenage years.

The Quick Take

  • What they studied: How the foods we eat influence our immune system’s ability to accept different foods without having allergic reactions, starting before birth and continuing through adolescence.
  • Who participated: This is a review article that examined hundreds of studies involving pregnant women, babies, children, and teenagers from multiple countries and research centers.
  • Key finding: A mother’s diet during pregnancy and breastfeeding appears to program her baby’s immune system to better tolerate foods. After birth, eating ultra-processed foods (like packaged snacks and fast food) may damage this protection by changing gut bacteria in harmful ways.
  • What it means for you: If you’re pregnant or planning to be, eating a healthy diet rich in whole foods may help protect your child from developing food allergies. However, this research is still emerging, and food allergies are complex—talk to your doctor about your specific situation.

The Research Details

This is a comprehensive review article, meaning scientists read and analyzed hundreds of existing studies on food allergies, gut bacteria, and diet. They looked at three main types of research: studies following real families over time, laboratory experiments with animals to understand how things work, and clinical trials where people tried different diets to see if allergies improved.

The researchers focused on a concept called “immune quorum sensing,” which is a fancy way of saying that immune cells communicate with each other based on how many bacteria and special chemicals are present in the gut. When this communication system works well, the body learns to tolerate foods. When it breaks down, allergies develop.

By combining evidence from all these different research approaches, the scientists created a framework—basically a roadmap—showing how diet influences this immune communication system at different life stages: during pregnancy, while breastfeeding, in early childhood, and through the teenage years.

Understanding how diet shapes immune tolerance is important because food allergies are becoming more common, especially in developed countries. By identifying the dietary factors that protect against allergies, doctors and parents can make better choices to prevent them. This approach focuses on prevention through nutrition rather than just treating allergies after they develop.

This is a review article, which means it synthesizes information from many studies rather than conducting original research. The strength of this work depends on the quality of the studies it reviewed. The authors included human studies, animal research, and clinical trials, which provides multiple types of evidence. However, because this is a review rather than a new experiment, the findings represent current scientific understanding rather than new discoveries. The research was published in a respected nutrition journal, which suggests it met scientific standards for publication.

What the Results Show

The research shows that what a pregnant woman eats significantly influences her baby’s immune system development. When mothers eat healthy diets with whole foods, their gut bacteria produce special chemicals called metabolites that cross into the baby’s bloodstream and help program the baby’s immune cells to be more tolerant of different foods.

After birth, the type of food a child eats continues to shape their gut bacteria and immune system. Children who eat lots of ultra-processed foods (packaged snacks, fast food, sugary drinks) develop different gut bacteria compared to children eating whole foods. These changes appear to make the immune system more likely to overreact to food proteins, leading to allergies.

The research found that ultra-processed foods consistently cause problems in three ways: they reduce the variety of gut bacteria, they allow harmful bacteria to multiply, and they reduce the production of protective chemicals that help the immune system stay calm around food proteins.

Across all the studies reviewed—from animal experiments to human trials—the pattern was consistent: better nutrition supports immune tolerance, while processed food diets increase allergy risk.

The research also identified that breastfeeding appears to transfer protective immune factors from mother to baby, and this protection is stronger when the mother has eaten well during pregnancy. Additionally, the timing matters—the period from pregnancy through the first few years of life appears to be especially important for programming immune tolerance. The studies suggest that dietary patterns in adolescence can still influence immune function, though the window for prevention may be narrower than in early childhood.

This review builds on decades of research showing that gut bacteria influence immune function. It adds a new perspective by connecting dietary patterns directly to immune communication systems and showing how this connection starts before birth. Previous research focused mainly on probiotics or single nutrients; this work emphasizes the importance of overall dietary patterns and the whole ecosystem of gut bacteria rather than isolated interventions.

As a review article, this work cannot prove cause-and-effect relationships the way a controlled experiment can. While the evidence is compelling, some studies reviewed were conducted in animals, which don’t always translate directly to humans. Additionally, food allergies develop through multiple pathways, and diet is just one factor—genetics, infections, and environmental exposures also play important roles. The review focuses mainly on IgE-mediated allergies (the type that cause immediate reactions) rather than other types of food reactions. Finally, most studies were conducted in developed countries, so the findings may not apply equally to all populations worldwide.

The Bottom Line

For pregnant women: Eat a varied diet rich in whole foods, vegetables, fruits, legumes, and whole grains. This appears to support healthy gut bacteria that can protect your baby from food allergies (Moderate confidence level). For parents of young children: Minimize ultra-processed foods and focus on whole foods to support healthy gut bacteria development (Moderate confidence level). For all ages: Maintain dietary diversity and limit processed foods, as this supports immune tolerance (Moderate confidence level). These recommendations should complement, not replace, guidance from your pediatrician or allergist.

Pregnant women and women planning pregnancy should pay special attention to these findings. Parents with family histories of food allergies may find this information particularly relevant. Healthcare providers working with allergy prevention should consider these dietary approaches. However, if someone already has a diagnosed food allergy, they should follow their doctor’s advice about avoidance and treatment—this research is about prevention, not treating existing allergies.

Changes in gut bacteria from dietary improvements can begin within weeks, but immune system programming takes longer. If a pregnant woman improves her diet, benefits to her baby’s immune system may be measurable at birth and continue developing through early childhood. For children already eating processed foods, switching to whole foods may improve immune tolerance over months to years, though the effect is likely strongest when started early in life.

Want to Apply This Research?

  • Track daily servings of ultra-processed foods versus whole foods (vegetables, fruits, legumes, whole grains, nuts). Set a goal to reduce processed food servings by 25% each week, measuring progress through a simple daily log with checkboxes for meal types.
  • Use the app to plan one additional whole-food meal per day, starting with breakfast. Create a simple shopping list feature that highlights whole foods and limits processed options. Set reminders to prepare meals at home rather than buying processed alternatives.
  • Track dietary patterns weekly and monitor any changes in digestive health or energy levels. For parents, note any changes in their child’s symptoms or tolerance over months. Create a long-term dashboard showing dietary quality trends over 3-6 month periods to visualize progress toward healthier eating patterns.

This review presents scientific evidence about dietary factors and food allergy development, but it is not a substitute for professional medical advice. Food allergies are serious conditions that require diagnosis and management by qualified healthcare providers. If you or your child has a suspected food allergy, consult with an allergist or immunologist. Pregnant women should discuss dietary changes with their obstetrician. This information is intended to support informed conversations with your healthcare team, not to replace their guidance. Individual responses to dietary changes vary, and what works for one person may not work for another.