Many U.S. babies may lack gut bacteria that train their immune systems

About three quarters of babies born in the United States may not have enough friendly microbes in their guts to protect against developing allergies, asthma and eczema, a new study suggests.

In a large study of more than 400 babies, 24 percent had no detectable levels of Bifidobacterium, gut microbes that digest sugars in breast milk, researchers report June 24 in Communications Biology. “Nondetectable levels of the most fundamental family type of bacteria for the infant was…