Can early and continued cow’s milk formula exposure prevent food allergies?

Early exposure to peanuts has been shown to reduce the risk of peanut allergy. Is the same true with cow's milk?

Roughly 20% of all babies born in the United States are supplemented with formula in their first few days of life.1 Although they may be exclusively breastfed later on, a new study raises questions about how early exposure to cow’s milk proteins might help shape future allergies.

The study, published in the Journal of Allergy and Clinical Immunology was done using a multilocation randomized control trial across 4 hospitals in Japan. During the trial, early formula feeding practices were investigated to determine if there were safe and practical ways to prevent the development of cow’s milk allergy.

Researchers examined when infants were exposed to cow’s milk proteins, for how long, and whether they later developed cow’s milk allergies. They concluded that early cow’s milk formula introduction—along with consistent exposure—may help prevent the development of cow’s milk allergy. When formula is used for the first few days, even as a supplement, and then discontinued, this could have the opposite effect and increase the chances of cow’s milk allergy development later on, the study notes.2

The significance of the study results, according to Tetsuhiro Sakihara, MD, lead author and a pediatrician at Heartlife Hospital in Okinawa, Japan, is that the strategy doesn’t compete with breastfeeding. Instead, research suggests that small-dose supplementation of cow’s milk formula—not enough to replace breast milk nutritionally—may have a protective effect against cow’s milk allergy development.

Cow’s milk allergies affect between 0.5% and 3% of infants globally by age 1 year. Genetics play a role in the development of some of these allergies, and cow’s milk allergies often appear alongside other food allergies. However, a number of environmental factors during the prenatal and postnatal periods can also have an impact.3

In this study, none of the 31 participants who avoided cow’s milk formula for the first 3 days of life later developed a cow’s milk allergy, suggesting that avoiding this type of formula in the days after birth could help prevent future allergies. However, when cow’s milk formula was used, continued exposure until at least 3 months of age—even in small doses—appeared to help prevent a later reaction, Sakihara said.

“We guess that early discontinuation of cow’s milk formula ingestion might be associated with the development of cow’s milk allergy,” said Sakihara.

A subgroup was investigated during the study involving infants who developed a cow’s milk allergy at 6 months of age. The research team broke these infants into categories, comparing those who stopped using cow’s milk formula before 1 month of age, at 1 to 2 months of age, and between 3 and 5 months of age. The group that stopped using cow’s milk formula the earliest had the highest rates of allergy development, according to the study.

“Early discontinuation of cow’s milk formula ingestion, particularly in the first month of life, increased the risk of cow’s milk allergy in infants who received cow’s milk formula in the first 3 days of life,” Sakihara says.

The research team used its study to come up with the suggestion that ingesting 10 milliliters or less of cow’s milk formula daily between 1 and 2 months of age could help prevent the development of cow’s milk allergies later on. The small volume means that this strategy doesn’t have to compete with breastfeeding as a nutrition source, Sakihara adds.

In fact, Sakihara says this strategy might be particularly helpful at helping infants who may have had supplemental formula feedings in the first few days of life avoid cow’s milk allergies once they become more exclusively breastfed.

References

1. Centers for Disease Control and Prevention. Breastfeeding Report Card. Updated September 17,2020.
https://www.cdc.gov/breastfeeding/data/reportcard.htm

2. Sakihara T, et al. Randomized trial of early infant formula introduction to prevent cow’s milk allergy. Food Allergy and Gastrointestinal Disease. 2021;147(1):224-232. doi: 10.1016/j.jaci.2020.08.021

3. Flom JD, Sicherer SH. Epidemiology of Cow's Milk Allergy. Nutrients. 2019;11(5):1051. doi: 10.3390/nu11051051