A new study suggests that this risk may be reduced if you avoid exposing your baby to cow’s milk in infancy. This can happen if your baby is given a cow’s milk formula in infancy. You probably know that exclusive breast feeding is recommended for the first six months after birth, but even if you are planning to feed your baby only breast milk, it is not unusual for infants to have some formula feeding to supplement breast milk in the first days and weeks of life.
The research on the link between exposure to cow’s milk and development of asthma is inconsistent. Some studies have suggested that exposing babies to cow’s milk in infancy may help prevent milk allergy. Other research suggests that babies with a family history of allergy could have allergies triggered by exposure to cow’s milk.
Researchers in Japan wanted to find out if cow’s milk formula in infancy would have any effect on the development of recurrent wheezing or asthma by age 2 in babies with a family history of allergies. Their study is published in the American Medical Association journal JAMA Network Open.
For the study, researchers from a medical university hospital in Japan followed over 300 infants with a family history of allergy in a mother, father or sibling. Although all the babies were breastfed, one group was fed only breast milk or a formula without cow’s milk (amino acid elemental formula). The other group was breastfed and supplemented with a cow’s milk-based formula. Feedings were started in the first days of life and continued for up to 5 months.
The researchers followed the babies until they were two years old. At age 2, babies who had symptoms of allergy such as eczema, atopic dermatitis, food allergy, asthma or wheezing were compared based on their feeding group. These were the key findings:
- Asthma or recurrent wheezing was diagnosed in about 10 percent of the babies in the no-milk formula group.
- Asthma or recurrent wheezing was diagnosed in about 18 percent of the milk-formula group.
Babies exposed to cow’s milk in their formula were almost twice as likely to develop wheezing or asthma. The researchers also looked at vitamin D levels (an indication of milk exposure) and total immunoglobulin E (IgE) in the babies. Both had a significant effect of asthma and wheezing risk. IgE is a protein that goes up with allergy. Babies who had the highest levels of vitamin D and IgE were the most likely to be diagnosed with asthma by age 2. This suggests that exposure to proteins in cow’s milk may trigger a babies immune system to become overactive. The researchers conclude that avoiding cow’s milk formula at birth can reduce the risk of asthma or recurrent wheezing in young children, especially in babies with high vitamin D or IgE levels.
Based on these findings, it would make sense to ask your pediatrician if you should avoid feeding your baby a milk-based formula if you have a strong family history of allergy or asthma.
