Breastfeeding reduces risk of diabetes in women

OAKLAND >> The benefits of breastfeeding are already known to lower a mother’s risk of developing breast and ovarian cancer, but mounting evidence now shows nursing a baby with a mother’s milk can also reduce her chances of developing diabetes.

A long-term national study by Kaiser Permanente’s research division, published Tuesday in JAMA Internal Medicine, indicates that breastfeeding for six months or longer cuts the risk of developing type 2 diabetes nearly in half for women throughout their childbearing years.

“We found a very strong association between breastfeeding duration and lower risk of developing diabetes, even after accounting for all possible confounding risk factors,” lead author Erica P. Gunderson, a senior research scientist, said in a statement.

Women who breastfed for six months or more had a 47 percent reduction in their risk of developing type 2 diabetes compared with those who did not breastfeed at all, the study said. Women who breastfed for six months or less had a 25 percent reduction in diabetes risk.

The researchers say that several biological mechanisms could explain the protective effects of breastfeeding, including the influence of lactation-associated hormones on the pancreatic cells that control blood insulin levels and thus impact blood sugar.

Gunderson and her colleagues analyzed data during 30 years of follow-up from the Coronary Artery Risk Development in Young Adults study, a national investigation of cardiovascular disease risk factors that originally enrolled about 5,000 adults ages 18 to 30 in 1985 and 1986, including more than 1,000 members of Kaiser Permanente Northern California.

The new report also found that

the long-term benefits of breastfeeding on reducing diabetes risk were similar for black women and white women — and women with and without gestational diabetes.

Black women, however,

were three times as likely as white women to develop diabetes within the 30-year study, a finding that is consistent with previous studies. Black women enrolled in the study were also less likely to breastfeed than white women.

This study included 1,238 black and white women who did not have diabetes when they enrolled in the

long-term study. Over the next 30 years, each woman had at least one live birth and was routinely screened for diabetes. The study’s participants also reported lifestyle behaviors such as diet and physical activity, as well as the total amount of time they breastfed their children.

“Unlike previous studies of breastfeeding, which relied

on self-reporting of diabetes onset and began to follow older women later in life, we were able to follow women specifically during the childbearing period and screen them regularly for diabetes before and after pregnancies,” Gunderson said.

She and her colleagues were also able to account for pre-pregnancy metabolic

risk, including obesity, lifestyle, a family history of diabetes and perinatal outcomes.

“We have known for a long time that breastfeeding has many benefits both for mothers and babies. However, previous evidence showed only weak effects on chronic disease in women,” Dr. Tracy Flanagan, director of women’s

health for Kaiser Permanente Northern California, said in a statement.

“This is yet another reason that doctors, nurses and hospitals — as well as policymakers — should support women and their families to breastfeed as long as possible,” Flanagan said.