Breast-feeding reduces risk of Type II Diabetes

Risk Reduction: Breast-Feeding May Help Keep Diabetes at Bay

By NICHOLAS BAKALAR

Published: November 29, 2005

Extended breast-feeding appears to lower the risk of Type 2 diabetes for the mother, The Journal of the American Medical Association reported last week.

For each year that a woman breast-feeds, she reduces her risk of developing diabetes by 15 percent, the study determined.

"I think our findings are just one more reason to breast-feed, and to breast-feed for as long as a mother can," said Karin B. Michels, associate professor of epidemiology at Harvard and the senior author on the study.

The researchers studied two groups of more than 100,000 women each, the participants in the Nurses' Health Study, which began in 1976, and those in the Nurses' Health Study II, beginning in 1989. All the women completed detailed health questionnaires every two years, and lactation history was assessed in 1993, 1997 and 2003.

In both groups, the duration of lactation was inversely associated with the risk of Type 2 diabetes in young and middle-aged women. Even after controlling for other diabetes risk factors - body mass index, amount of exercise, diet and smoking - the correlation persisted. As the women got older, however, the correlation weakened.

The beneficial effect, the scientists concluded, begins to build after six months of lactation, and the artificial suppression of lactation increases the risk of diabetes. "It may not be a good idea in general to suppress lactation," Dr. Michels said. "If a woman can overcome the potential obstacles to breast-feeding, it would be better for her and her babies' health if she continues to breast-feed."

The exact physiological mechanisms involved are not well understood, but it is clear that lactation improves glucose metabolism, which malfunctions in diabetes.