Nourishing Immunity: How Maternal and Infant Diets Can Help Prevent Food Allergies

Author: Janice Man

Editors: Sarah Armes, Sarah Anderson

Acknowledgments: NNEdPro Global Institute for Food, Nutrition and Health; International Academy of Nutrition Educators (IANE); BMJ Nutrition, Prevention & Health; Author of the Article – Ralf G Heine; ChatGPT.

The prevalence of food allergies is increasing globally, with many cases persisting into later childhood and adulthood. Atopic dermatitis (eczema), particularly when it appears early and with greater severity, is a known indicator of increased food allergy risk. While genetic predisposition plays a role, environmental exposures, like air pollution, smoking, and low sunlight, also contribute to immune system dysregulation. Because individual risk is difficult to assess, infant feeding remains one of the few modifiable factors that parents can control.

This review explores how maternal diet during pregnancy and breastfeeding, as well as infant feeding practices, influence immune development and allergy risk. It also highlights the role of the gut microbiome and summarises global guidelines supporting early allergen introduction.

Maternal diet during pregnancy and lactation 

While no specific maternal diet has been conclusively shown to prevent food allergies, what mothers eat can shape the baby’s immune system. Diets high in ultra-processed foods, added sugars, and unhealthy fats, common in Western dietary patterns, may increase allergy risk in children. In contrast, diets rich in fibre and whole foods help support a diverse maternal gut microbiome, which may contribute to immune tolerance in the infant.

Maternal diets high in omega-3 fatty acids 

Omega-3s, found in oily fish, flaxseed and walnuts, have anti-inflammatory effects and may aid in immune system development. Although some studies suggest fish oil supplements during pregnancy reduce allergy-related markers, the evidence is inconsistent. For now, the guidelines don’t recommend omega-3 supplements specifically to prevent food allergies.

Vitamin D supplementation during pregnancy 

Vitamin D plays a key role in immune regulation and may help develop tolerance to allergens. Deficiency has been linked to a higher risk of allergies, notably to eggs and peanuts. However, excessive vitamin D may increase allergy risk, showing a U-shaped relationship. While sun exposure and foods like fatty fish can help meet vitamin D needs, current guidelines don’t support routine supplementation for allergy prevention.

Breastfeeding  

Breast milk provides antibodies, beneficial bacteria, and trace dietary antigens that can help build immune tolerance. However, breastfeeding alone does not significantly protect against food allergies. Other factors, such as genetics, maternal microbiome, and environmental exposures, may moderate its effect. Variability in breast milk composition, including differences in human milk oligosaccharides (HMOs) and microRNAs (miRNAs), may also influence allergy outcomes by shaping the infant gut microbiome.

Formula feeding 

Formula serves as the primary alternative for infants who are not breastfed. No current formula has been definitively shown to prevent food allergies. Early exposure to cow’s milk-based formula may increase the risk of milk allergy in high-risk infants. Some evidence suggests that partially hydrolysed formulas (PHF) may reduce eczema, but their role in allergy prevention is uncertain. More high-quality studies are needed to draw firm conclusions, especially since results vary by formula type and study design.

Complementary weaning diet and early allergen introduction  

Introducing solid foods, including common allergens like peanut and egg, around 6 months of age is now a key strategy for allergy prevention. This shift is based on strong evidence, including the LEAP (Learning Early About Peanut Allergy) trial, which found an 81% reduction in peanut allergy among high-risk infants who consumed peanuts early (4-11 months of age). The EAT (Enquiring About Tolerance) trial also supported early allergen introduction, though adherence was challenging. 

Despite the evidence, implementing early allergen introduction in real-world settings is complex. Parents often feel unsure about when and how to introduce allergens or how much to give. Clear, consistent guidance from healthcare providers can help families navigate this process effectively. 

Eczema and early allergen exposure

Infants with eczema are at higher risk for developing food allergies, especially when allergens enter through broken or inflamed skin. Introducing small amounts of allergenic foods, like peanut and egg, into the infant’s diet around 4 to 6 months of age may help the immune system build tolerance. This strategy could further reduce allergy risk in combination with regular skin care, such as daily moisturising to maintain the skin barrier. However, more research is needed to clarify best practices for this combined approach.

Conclusion 

Maternal and early infant diets are modifiable factors that influence food allergy development through immune, epigenetic, and microbiome-related pathways. Exclusive breastfeeding has many health benefits, but doesn't prevent food allergies alone. Early allergen introduction, especially egg and peanut, between 4 and 6 months of age, is a proven method to reduce allergy incidence.

Maternal allergen avoidance is not recommended, and current evidence does not support the supplementation of omega-3, vitamin D, probiotics, or prebiotics solely for allergy prevention. Combining early allergen exposure with diligent skin care may offer additional benefits for infants with eczema.

For more details, read the full study here. 

Method

ChatGPT was used for sectioning the topics in this blog and to clean up grammar.

References 

Ralf G Heine - Dietary strategies for early immune modulation in primary food allergy prevention: BMJ Nutrition, Prevention & Health. https://doi.org/10.1136/bmjnph-2023-000678