Could babies be at higher risk of developing Type 1 diabetes from drinking formula made from cow's milk? That idea has been circulating for some time but the evidence has been scant and contradictory. A study published Tuesday makes it seem less likely.
There are two types of diabetes, and both are on the rise. It's clear that a major driving force behind the increase of Type 2 diabetes, which mainly affects adults, is the eating habits that are also driving the rise of obesity.
A much bigger mystery is what has been propelling the increase of Type 1 diabetes (once called juvenile diabetes). This disease usually strikes children and takes hold when a child's immune system starts attacking cells in the pancreas that produce insulin.
Researchers in Finland have been trying to tease apart the role of cow's milk for many years. In 2010 they published some intriguing results. They looked at antibodies that appear to be part of the Type 1 diabetes process. Studying 230 infants, they found these antibodies were more common in babies who consumed formula produced from cow's milk, compared with babies who were fed a formula in which those milk proteins had been broken down.
The results from that small study only suggested that whole proteins from cow's milk are triggering the immune reaction that leads to type 1 diabetes. But if that proved to be the case, there would be an easy way to reduce the risk of the disease: simply make sure baby formula was based on degraded milk proteins rather than whole proteins.
To find out whether that would indeed work, the scientists devised a very ambitious experiment, involving 2159 newborns studied at 78 study centers in 15 countries.
Half those babies were given formula with regular cow's milk proteins for at least 60 days. The other half got a formula in which the milk proteins had been predigested.
The trial then followed these children until the youngest reached 10 years of age. And the scientists then tallied up the cases of diabetes. They now report in the journal JAMA, the journal of the American Medical Association, that it made no difference whether these children had been fed formula with whole-milk proteins or those with the proteins broken down.
"These findings do not support a need to revise the dietary guidelines for Type 1 diabetes," the authors wrote. Dr. Mikael Knip at the Children's Hospital, University of Helsinki led the long list of authors.
"After more than 15 years of effort, this study puts to rest the controversy regarding the potential role of cow's milk formula in the development of Type 1 diabetes," said Dr. Dorothy Becker, the study's chief U.S. collaborator, at Children's Hospital of Pittsburgh, in a statement. "This once more shows us that there is no easy way to prevent Type 1 diabetes."
Case closed? Not yet. Other scientists have pointed out that the issue with cow's milk may not be its intact proteins, but some other factor.
It's also hard to figure out what role breast-feeding might play.
Babies given formulas based on cow's milk might not breast-feed as long, and they might get less of some unknown benefit of breast-feeding. One recent study found that breast-feeding seemed to reduce the risk of Type 1 diabetes – though, perplexingly, this study found that it didn't matter how much or how little a mother breast-fed her infant.
So the quest to prevent Type 1 diabetes continues.
Contact Richard Harris at rharris@npr.org .
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