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Does Breastfeeding Reduce the Risk of Diabetes?
Yvonne E. Vaucher, M.D., M.P.H.
Type 1 Insulin Dependent Diabetes (IDDM) is due to a lack of insulin production as a result of autoimmune destruction of the pancreatic b cells. Type 1 diabetes is multifactorial. Environmental factors (e.g., viral infection, nutrition, stress, toxins) are thought to trigger the disease in genetically susceptible individuals.1 Less than 5% of genetically susceptible individuals ever develop the disease. Diabetic fathers confer a higher genetic risk to their offspring than do diabetic mothers.
Breastfeeding is associated with lower risk of developing Type 1 diabetes, particularly in those children at the highest genetic risk, although methodological questions regarding selection and recall bias can be raised for many studies. Early weaning or exposure to cow's milk in the infant's diet at < 3 months of age as well as high individual or national levels of cow's milk consumption are associated with an increased incidence of Type 1 diabetes. Children with early onset Type 1 diabetes have more autoantibodies that crossreact with various cow's milk proteins. In addition, an increased number of autoantibodies directed against the pancreas have been found in genetically high risk infants who were weaned before 2 months of age.2 Hence the intriguing, but still unanswered, question: does early exposure to cow's milk protein in infancy result in
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sensitization and production of autoantibodies that destroy the pancreas and cause Type 1 diabetes?3 Of note, early exposure to soy and wheat proteins has also been associated with an increased risk of Type 1 diabetes in susceptible animals. Benefits of breastfeeding which might decrease the risk of Type 1 diabetes include reducing the infant's exposure to immunogenic proteins such as cow's milk protein and/or strengthening the infant's own immunologic protection. Immunologic protection might be conferred by reducing the risk of viral infection, by decreasing intestinal permeability to foreign proteins, or by increasing immunologic tolerance of foreign proteins.
A protective effect of feeding formula containing hydrolyzed cow's milk protein instead of standard formula containing intact cow's milk protein has been demonstrated only in genetically susceptible, experimental animals. However, a multinational, randomized, double-blinded, controlled, "Trial to Reduce IDM in the Genetically at Risk" (TRIGR) has just begun to test the cow's milk sensitization hypothesis in high risk infants. In this trial, 3000 genetically susceptible infants will be weaned from exclusive breastfeeding to either standard cow's milk based formula or to protein hydrolysate formula. The longterm effect of the two weaning regimens on the development of cow's milk antibodies and the risk of developing diabetes will be determined.
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