According to Food Allergy Research & Education (FARE), 32 million Americans—nearly 11% of adults and 8% of children—suffer from food allergies. Those 32 million Americans report allergies to more than 170 different foods, led by shellfish (8.2 million), milk and peanuts (6.1 million apiece). That number has steadily risen over the last generation; FARE reports food allergy prevalence among children increased 50% from 1999 to 2011.The World Allergy Organization suggests approximately 2.5% of the global population—195 million people—is affected by food allergies.
However, new research out of Sweden indicates an association between cow’s milk consumption by lactating mothers and a lower allergy rate in their children. The study, “Maternal Intake of Cow’s Milk during Lactation Is Associated with Lower Prevalence of Food Allergy in Offspring,” by Mia Stråvik et al., assessed maternal diet during pregnancy and lactation by repeated semi-quantitative food frequency questionnaires given to 508 women. According to the study’s authors, “Fatty acid proportions were measured in maternal breast milk and erythrocytes. Allergy was diagnosed at 12 months of age by a pediatrician specialized in allergy.”
The results of the study were promising, showing “an increased maternal intake of cow’s milk during lactation, confirmed with biomarkers (fatty acids C15:0 and C17:0) in the maternal blood and breast milk, was associated with a lower prevalence of physician-diagnosed food allergy by 12 months of age.”
Interestingly, the researchers also noted another conclusion from their study: Intake of fruit and berries during lactation was associated with a higher prevalence of eczema, also known as atopic dermatitis, at 12 months. The authors did note this surprising conclusion remains to be confirmed with dietary biomarkers, writing, “even though the association between fruit and berries and atopic eczema is strongly significant, one might argue that our results are surprising since resistant starch and dietary fiber is favorable for the gut microbiome and might enhance oral tolerance, which may decrease allergy risk. To verify our results, further studies with validated biomarkers for fruit intake related to eczema development are needed.”
Even so, the two results led the researchers to a clear conclusion.
“Our results suggest that maternal diet modulates the infant’s immune system, thereby influencing subsequent allergy development,” the authors concluded, though the exact mechanism is still unclear. The authors suggested possible theories, including the possibility that substances in milk stimulate the child’s immune system to mature. “More specifically,” the authors wrote, “[milk’s] content of proline-rich polypeptides (PRP) have been found to enhance T-cell maturation and osteopontin to modulate immune function and stimulate Th1/Th2 shifting.”
Another possibility is that higher milk consumption leads to lower consumption of polyunsaturated fats, which can counteract the maturation of a child’s immune system, according to co-author Malin Barman.
The researchers plan further follow-up when the children involved in the study turn 4 years old.