The researchers -- led by Christopher G. Owen, PhD. -- examined the results of seven studies that involved nearly 77,000 participants, and found that babies who were breastfed were 15 to 56 percent less likely to develop type 2 diabetes when they were older.
"Breastfeeding in infancy is associated with a reduced risk of type 2 diabetes," Owen said. "Whether this effect is attributed to a difference in the content of breast milk compared to formula, or whether the family environment and nurture of breastfed infants is the cause remains to be established."
Over the past 30 years, the number of middle-aged Americans diagnosed with type 2 diabetes has doubled, and more than a million new cases are diagnosed in the United States every year. Although obesity is the largest factor in developing the disease, experts say nutrition early in life may contribute to the onset of the disease in later years.
The University of London researchers estimated that roughly 5 percent of Western type 2 diabetics can attribute their cases to formula feeding.
"Although this effect is important, it is modest compared with the population benefits of reducing overweight and obesity later in life," Owen said.
However, according to University of Rochester professor of pediatrics Dr. Ruth Lawrence, the researchers may have underestimated the impact of breastfeeding on adult-onset diabetes.
"Babies who are exclusively breastfed seem to have a big advantage," Lawrence said. "There is not one single study suggesting that formula is better than breast milk."
Owen says more research is needed to bolster the link between breastfeeding and reduced risk of type 2 diabetes.
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