Cows' Milk, Diabetes Connection Bolstered
Seppa, N., Science News
Many studies have linked cows' milk consumed by babies to subsequent diabetes, but some researchers still doubt that it causes the disease. The association is based on animal experiments, they note, or indirect evidence (SN: 10/19/96, p. 249), such as studies in which parents of diabetic children try to recollect when their babies first started drinking milk-based formula.
Now, Finnish researchers have avoided the vagaries of poor recall by studying children from birth. In so doing, they have added to the case against cows' milk.
By monitoring babies in diabetes-prone families, the scientists find that infants getting formula that includes cows' milk are more likely later to develop the immune reactions associated with juvenile-onset, or type I, diabetes than are babies getting a substitute. The scientists reported the findings this week in San Diego at the 59th Annual Scientific Sessions of the American Diabetes Association.
The researchers tracked, until age 8 months, 173 newborns in Finland who had a close relative with type I diabetes. To augment their mothers' milk, half of these babies received milk-based formula and the rest got a formula in which the cows' milk proteins had been broken into fragments called peptides. The two formulas taste and smell the same, so parents and researchers didn't know which one a baby was drinking.
Babies' immune systems largely ignore cows' milk proteins that have been chopped up. However, contact with one intact protein in cows' milk, bovine insulin, may set off a destructive process, suggest immunologist Outi Vaarala and her colleagues at the University of Helsinki. The immune system would attack pancreas islet cells that make human insulin, which resembles bovine insulin, and would produce antibodies.
At 2 years of age, 10 of 89 children getting cows' milk formula had formed antibodies associated with type I diabetes. However, only 3 of 84 babies receiving the treated milk showed these antibodies, says Hans K. Akerblom, a pediatrician at the University of Helsinki.
These autoimmune antibodies, or autoantibodies, are made by immune B cells and appear to dispose of damaged pancreatic islet cells, says Hans-Michael Dosch, an immunologist at the Hospital for Sick Children in Toronto. …