Cows' Milk, Diabetes Connection Bolstered

By N. Seppa

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 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 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. 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.

These autoimmune antibodies, or autoantibodies, are made by immune B cells and appear to dispose of damaged pancreatic islet cells. The antibodies indicate that bovine insulin might be spurring an immune system T-cell reaction against the child's own islet cells, he says. Insulin regulates sugar metabolism in the body. Research had already determined that having one type of autoantibody to insulin indicates that a baby has roughly a 4 in 10 chance of contracting type I diabetes within the next decade. Having more types of these autoantibodies is a sign of greater risk; having three imparts an 80 to 90 percent likelihood of getting type I diabetes. In this study, 3 of the 10 children in the cows' milk group who had diabetes-related autoantibodies showed one type of such antibody, and the rest had two or more.

The precise cause of diabetes remains unclear but the evidence against cows' milk is piling up. As an example, in Puerto Rico, fewer than 5 percent of mothers breast-feed their children. Instead, nearly all use formula made from cows' milk. Meanwhile, type I diabetes incidence in Puerto Rico is roughly 10 times the rate seen in Cuba, where breast-feeding is nearly universal. Such findings suggest that the problem may be cows' milk ingested in the first few months of life.

We have an extensive article on the pancreas and how it functions. Read about the pancreas here.