A natural compound found in breast milk, known as transforming growth factor TGF ß-1, protects infants from developing wheezing. This helps explain the well-known anti-wheezing effect of breastfeeding. Researchers from the University of Arizona, USA, conducted a study with 243 infants and their mothers. They measured the levels of several chemicals, including TGF ß-1, in the breast milk of all women several days after they gave birth. It was found that infant wheezing became less common as the duration of breastfeeding increased. Moreover, the risk of wheezing fell as TGF ß-1 levels in breast milk rose. No clear relationship to wheezing was seen with the other chemicals tested. Further analysis showed that mothers who breastfed for several months and had high TGF ß-1 levels were 78 percent less likely to have a baby with wheezing than mothers who breastfed for only a few months and had low TGF ß-1 levels. According to the researchers, further studies are needed to determine exactly how TGF ß-1 may protect against wheezing.

Journal of Allergy and Clinical Immunology, November, 2003