Researchers say they have identified a compound in breast milk that combats the growth of infection-causing bacteria in infants. The compound is called Glycerol Monolaurate (GML), and the amount of GML in human breast milk is more than 200 times higher than in cow’s milk. Infant formula has no GML, according to the study. Along with fighting harmful bacteria, GML promotes the growth of beneficial bacteria.
“Our findings demonstrate that high levels of GML are unique to human breast milk and strongly inhibit growth of pathogenic bacteria,” senior author Dr. Donald Leung, professor of pediatrics at National Jewish Health in Denver, said in a hospital news release. The study found that human breast milk inhibits the growth of the harmful bacteria Staphylococcus aureus, Bacillus subtilis and Clostridium perfringens, but neither cow’s milk or infant formula had any effect on those bacteria.
Meanwhile, human breast milk did not inhibit the growth of the beneficial bacteria Enterococcus faecilis, and breastfed babies have high levels of beneficial bifidobacteria, lactobacilli and enterococci bacteria, according to the researchers. They said that when they removed GML from human breast milk, it no longer protected against S. aureus. When they added GML to cow’s milk, it helped protect against harmful bacteria.
“While antibiotics can fight bacterial infections in infants, they kill the beneficial bacteria along with the pathogenic ones,” said study first author Patrick Schlievert, a professor of microbiology and immunology at University of Iowa. “GML is much more selective, fighting only the pathogenic bacteria while allowing beneficial species to thrive. We think GML holds great promise as a potential additive to cow’s milk and infant formula that could promote the health of babies around the world,” Schlievert said in the release.
The study also found that GML inhibits inflammation in epithelial cells, which line the gut and other mucosal surfaces. Inflammation can damage epithelial cells and contribute to increased risk for bacterial and viral infections.