New Clue to Milk and Diabetes Link?
Study Shows Protein in Cow's Milk Infant Formula May Raise Risk of Later Diabetes
May 1, 2008 -- The reaction of an infant's immature immune system to a protein found in cow's milk infant formula may explain the suspected link between early consumption of cow's milk and an increased risk of developing type 1 diabetes later, according to a new study.
But experts who reviewed the study for WebMD say the research is mixed on the suspected link and the new report does not offer conclusive proof of cause and effect. While these experts strongly support breastfeeding, they say those mothers who can't or choose not to breastfeed shouldn't be alarmed by the report.
The Formula-Diabetes Theory
The protein under study, called beta-lactoglobulin, is found in cow's milk but not human breast milk. It is similar in structure to the human protein glycodelin, writes Marcia F. Goldfarb, author of the new report.
The report is published in the letters section of the Journal of Proteome Research. Goldfarb directs Anatek-EP, a contract protein research laboratory in Portland, Maine.
An infant's immature immune system may destroy the glycodelin in an effort to destroy the look-alike "foreign" protein beta-lactoglobulin, Goldfarb says.
Glycodelin controls the production of the body's T-cells, which help protect against infection. If glycodelin is destroyed, there could be an overproduction of T cells, she says.
Type 1 diabetes is thought to be caused when T-cells destroy the insulin-secreting beta cells in the pancreas, Goldfarb writes.
The Cow's Milk-Diabetes Link Study
In the report, Goldfarb notes the conflicting results of studies looking at early introduction of formula (before four months) and diabetes.
She reports her results, evaluating blood samples taken from five adults without diabetes and five children and teens who all had type 1 diabetes.
In the adults, she found two had antibodies to beta-lactoglobulin.
In the children, all five had antibodies to beta-lactoglobulin.
While other researchers have noted that beta-lactoglobulin may generate antibodies to glycodelin, Goldfarb proposes the next step: that the immature immune system sees the beta-lactoglobulin as foreign, produces the antibody which cross-reacts with the glycodelin, and triggers the diabetes.