By Michael Burton
Provocative studies caused a stir several years ago by implicating the protein BSA, found in cow's milk, as a trigger of early autoimmune response in infants, leading to Type I diabetes, and suggesting that breast-feeding might have a protective effect. Where does the research stand today?
In a 1994 analysis in the journal Diabetes Care, Hertzel Gerstein, M.D., of McMaster University in Hamilton, Ontario, combined the results of more than a dozen studies, including the few published cow's-milk studies and a larger number of breast-feeding studies. His conclusions: Breast-feeding for less than three months statistically increases risk for getting Type I by 40 percent; exposure to cow's milk before 4 months increases the risk by 60 percent.
Some diabetologists have found those numbers persuasive. "It's still a terribly woolly area," says Edwin Gale, M.D., of London's St. Bartholomew's Hospital, "but these epidemiological datawhile not an explanation for IDDMsuggest that prolonged breast-feeding might be a good thing for genetically at-risk children. We still need a controlled study, however, before we can be sure."
But a new analysis, published in Epidemiology, January 1996, by Jill M. Norris, Ph.D., assistant professor of preventive medicine at the University of Colorado Health Sciences Center, takes issue with Gerstein's conclusions. "The results of most of these studies are inconsistent," she says, "and the associations are weak." The biggest limitation: reliance on data from mothers, asked on average ten years after the fact, about what they fed their infants and when.
Dr. Norris's own research on infant diet backs up her assessment. As a co-investigator on the DAISY study of genetically at-risk children, she says, "We see no statistical association between either breast-feeding or exposure to cow's milk and the development of prediabetic autoimmunity."
Diet is an important and fertile ground for study, she adds. "We need more specifics on what, when, and how the diets of these children evolve and interact with their growing immune systems."
What about recommendations to avoid cow's milk or prolong breast-feeding? "I don't think we can say these will reduce risk," she says. "The data we have on infant diet are not precise or accurate enough to suggest such recommendations."
From COUNTDOWN magazine, Spring 1996, Vol. XVII, No. 2
Copyright © 1996 Juvenile Diabetes
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