Breastfed babies are believed to have fewer allergic conditions, such as eczema and food allergies, than bottle-fed babies; but the reason is not well understood. Therefore, if the molecules identified by the study can be put into a formula, it could help reduce the chances of babies developing allergies, the scientists said.
Atopic conditions, such as food allergies, asthma and a skin condition called atopic dermatitis, occur in about a third of children due to inappropriate activation of the immune system to exposure to environmental factors.
“Babies who breastfeed for more than three months may be at a lower risk for these conditions, but we don’t fully understand the biology behind this,”stated dr. Steven Hicks, associate professor of pediatrics and pediatrician at Penn State Health Children’s Hospital.
Hicks’ previous studies have shown how micro-ribonucleic acids (miRNAs), or small molecules that can regulate gene expression throughout the body, can be used to diagnose certain health conditions such as concussion or autism.
There are nearly 1,000 different types of miRNAs in human breast milk and their composition varies due to maternal characteristics such as weight, diet and genetics. Hicks and his team therefore hypothesized that four of these miRNAs could have a protective effect against infant allergies.
Of the infants studied, 41 (25%) developed atopic dermatitis, 33 (20%) developed a food allergy and 10 (6%) had wheezing. Babies who did not develop atopy consumed, on average, higher amounts of miRNA-375-3p (miR-375) in their mother’s breast milk than babies who developed atopy. There were no other differences in maternal characteristics, infant characteristics, or environmental exposure between atopic and non-atopy infants. The researchers also found that levels of this miRNA increased during breastfeeding and that mothers with a lower body mass index tended to have a higher concentration of miR-375.
“The fact that miR-375 levels increased over the course of lactation may explain why sustained breastfeeding has been associated with reduced atopy in certain studies.”said Hicks. He noted that the largest increase in miR-375 occurred in the first month after birth, but the upward trend continued between months one and four. “Unlike formula milk, which does not contain human miRNAs, miR-375 is present in over 99% of human milk samples and represents just under 1% of all miRNAs in human milk.”
According to Hicks, the findings of this study could lead to new interventions to prevent babies from developing allergies, such as efforts to increase miR-375 levels in the mother’s breast milk.
Hicks also said that with further research, miR-375 could one day be added to the formula, which currently contains no miRNAs, to address the disparity that bottle-fed babies are more likely to develop atopic disorders.
“Other studies measuring miRNA content in the formula have failed to identify measurable amounts of human miRNA,”he explained to FoodNavigator. “However, research by our team and others has shown that breast milk contains robust amounts of miRNAs.
“The technology to include miRNAs in the formula already exists,”he added. “But before adding miRNAs to the formula, we need to verify that 1) specific miRNAs do indeed protect against specific diseases (such as allergies); and 2) the inclusion of miRNAs does not cause unexpected side effects. So several steps are still needed before we can apply this information to the production of formulas.”
Small molecules in breast milk may protect babies from developing allergies
American Journal of Clinical Nutrition