Drinking milk while pregnant, breastfeeding may lower allergy risk in children

Women who drink more cow’s milk during pregnancy and while breastfeeding may lower their child’s risk for developing food allergy, according to research published in Nutrients.

“Diet is a factor where parents themselves can have direct influence,” Mia Stråvik, a doctoral student in the division of food and nutrition science in the department of biology and biological engineering at Chalmers University of Technology in Gothenberg, Sweden, said in a press release. “It is quite common nowadays for young women to avoid drinking milk, due in part to prevailing trends and concerns, some of which are linked to myths about diet.”

Stråvik and colleagues evaluated participants from the Nutritional impact on Immunological maturation during Childhood in relation to the Environment (NICE) study, a birth cohort study at a hospital in Sweden. The researchers assessed maternal diet in the past month using three semi-quantitative food frequency questionnaires, which were sent to participants via email at 34 weeks gestation, 1 month after birth and 4 months after birth.

A pediatrician specializing in allergology evaluated infants for allergic disease when they were 12 months of age. The researchers collected and assessed maternal blood samples at 28 weeks gestation and 4 months after birth for total fatty acid composition in erythrocytes. They also collected breast milk samples at 1 month and 4 months after birth to assess for fatty acid composition.

A total of 508 mother-infant pairs were included in the study, with a median maternal age of 30 years.

Among the infants, 7.7% had food allergy, 6.5% had atopic eczema and 6.5% had asthma at 12 months of age.

Among children who developed food allergy, eight were only allergic to eggs, 15 were only allergic to cow’s milk, and five were only allergic to fish. Among food-allergic children, 10 were allergic to multiple foods.

Stråvik and colleagues found that higher maternal consumption of dairy products was associated with a lower prevalence of food allergy, particularly at 4 months after birth.

To account for mothers who avoided consuming specific foods after observing early allergic symptoms in their child, the researchers conducted secondary analyses that excluded these mother-infant pairs. In these analyses, increased maternal cow’s milk intake during lactation remained significantly associated with a lower prevalence of food allergy in children.

In additional analyses that were conducted among children who had continuous reaction to food after 1 year of age, the researchers found that the association between increase maternal cow’s milk intake during lactation and lower food allergy prevalence in children remained statistically significant.

Stråvik and colleagues determined that increased maternal consumption of cow’s milk, when confirmed by fatty acid biomarkers in blood and breast milk, was associated with a lower risk for infants developing food allergy by 12 months of age.

While the exact cause of this association was not determined in the study, the researchers suggested that maternal diet impacts the child’s immune system and subsequently affects allergy development.

“One hypothesis is that cow’s milk contains something that activates the child’s immune system and helps it to develop tolerance,” Malin Barman, PhD, a researcher at Chalmers University of Technology, said in the press release. “This as-yet unknown cause could be found in the fat of the milk or in its protein content.”

Therefore, she added that the cow’s milk itself may not impact the immune system.

“Then it might be more simply a matter of a higher intake of milk fats leading to a relatively lower intake of polyunsaturated fats,” she said. “This would help, because we believe high levels of polyunsaturated fat in a mother's diet can counteract the maturation of a child's immune system at an early age.”

References:

Stråvik M, et al. Nutrients. 2020;doi: 10.3390/nu12123680.

Eurekalert. Drinking milk while breastfeeding may reduce the child's food allergy risk. https://www.eurekalert.org/pub_releases/2020-12/cuot-dmw122020.php. Accessed January 4, 2020.