Impact of Maternal Diet During Pregnancy and Breastfeeding on Child Food Allergy Development

Many expecting and new mothers often question whether their dietary choices during pregnancy and breastfeeding can influence their child's risk of developing food allergies. This concern has prompted extensive scientific research aimed at understanding the relationship between maternal diet and immune responses in infants.

The exposure of a fetus and infant to food allergens occurs through various pathways. During pregnancy, food allergens can cross the placental barrier and be found in amniotic fluid, which the fetus ingests. Postnatally, allergens pass into breast milk, exposing the developing immune system to potential antigens early on. These exposures are believed to aid the immune system in recognizing these foods as harmless, potentially reducing the likelihood of allergies developing later.

Food allergies are immune responses where the body reacts adversely to specific foods. Common triggers include eggs, cow's milk, peanuts, tree nuts, sesame, soy, wheat, and seafood, although this varies internationally. Symptoms can range from mild reactions like hives and swelling to severe responses such as difficulty breathing and collapse. Notably, food allergens ingested by the mother can transfer to the fetus and infant through the placenta and breast milk, respectively, playing a role in early immune tolerance.

Research indicates that beneficial antibodies against food allergens are present in breast milk, especially when mothers include allergenic foods like eggs, peanuts, wheat, and milk in their diet during breastfeeding. Higher levels of these antibodies in infants have been associated with a lower risk of developing allergies. Conversely, lower antibody levels have been linked to increased allergy risk.

However, despite the biological plausibility, there is no conclusive evidence yet that specific maternal diets during pregnancy and breastfeeding can prevent food allergies. Studies have produced mixed results, often due to differing methodologies, populations, and confounding factors. Large ongoing studies, such as the PrEggNut and Nuts For Babies, aim to clarify these associations by examining how maternal consumption of eggs, peanuts, and cashew nuts influences children's allergy development.

Current guidelines recommend that pregnant and breastfeeding women not avoid common allergenic foods unless they themselves are allergic. The emerging consensus is that exposing infants to allergens around six months of age, through diet, may actually reduce allergy risk. Introducing foods like peanuts and eggs early, and maintaining regular inclusion in the child's diet, may help promote tolerance.

Until definitive answers emerge from ongoing research, healthcare professionals suggest that mothers follow a balanced diet without unnecessary restrictions. The goal remains to support overall maternal and infant health while allowing natural exposure to allergenic foods, which could be beneficial in preventing allergies in children.