Cow's milk: new link to diabetes?

The debate over whether an infant's ingestion of cow's milk spurs the emergence of diabetes later on seems to seesaw between yes and no, depending on the results of the latest research. As recently as August, doctors at the University of Colorado School of Medicine in Denver downplayed the likelihood of any such link after analyzing a nutritional survey and blood tests of 253 diabetes-prone children (SN: 9/7/96, p. 151).

Now, the balance may tip once more, with a new report showing that some people with insulin-dependent diabetes mount an immune response to the protein beta casein, which makes up 35 percent of the total protein in cow's milk. (All four forms of casein together account for less than one-fourth of the protein in human milk.) Maria Gisella Cavallo and her coworkers at the University of Rome found that 24 of 47 people with diabetes had a flood of white blood cells, or T cells, primed to attack casein. In contrast, just 1 of 36 healthy volunteers and none of 10 people with thyroid disease mounted an immunological assault on that milk protein.

The results, which mirror those of an earlier trial in Finland, "reinforce the concept" that beta casein might trigger diabetes, Cavallo and her colleagues contend in the Oct. 5 Lancet.

Although the mechanism remains unclear, researchers postulate that the T cells are diverted from their offensive against beta casein and redirected toward insulin-producing beta cells in the pancreas.

Drawing on the Finnish study and others, a working group of the American Academy of Pediatrics recommended in 1994 that parents avoid feeding cow's milk to their babies. But an editorial in the Aug. 28 Journal of the American Medical Association argued that the risks of malnutrition "in growing numbers of children" vastly outweigh the diabetes-preventive benefits of a diet free of cow's milk.