Mothers who breastfeed seem to have a lower long-term risk of developing a collection of risk factors for diabetes and heart disease than women who bottle-feed, a new study suggests.

Researchers found that among 700 women followed for 20 years, those who had breastfed were less likely to develop metabolic syndrome - a cluster of risk factors for type 2 diabetes and heart disease that includes abdominal obesity, elevated blood pressure and blood sugar, lower-than-desirable levels of “good” HDL cholesterol and elevated triglycerides (a type of blood fat).

What’s more, the apparent protective effect was stronger among women with a history of gestational diabetes, a form of diabetes that arises during pregnancy and goes away after childbirth.

Although it is temporary, gestational diabetes does raise a woman’s odds of eventually developing type 2 diabetes.

These latest findings suggest that breastfeeding might help diminish that excess risk, said lead investigator Dr. Erica P. Gunderson, a research scientist at Kaiser Permanente’s Division of Research in Oakland, California.

However, she told Reuters Health, while the study suggests breastfeeding has a “strong protective effect” against metabolic syndrome, more research is needed to see whether that translates into lower rates of diabetes and heart disease.

The study, published online in the journal Diabetes, included 704 women who were between the ages of 18 and 30 and free of metabolic syndrome at the outset, and who gave birth for the first time during the study period.

Over 20 years of follow-up, 120 were diagnosed with metabolic syndrome.

The researchers found that among women with no history of gestational diabetes, those who had breastfed for more than one month were anywhere from 39 percent to 56 percent less likely to develop metabolic syndrome - depending on how long they had breastfed.

Among women with a history of gestational diabetes, breastfeeding for more than one month was linked to a 44 percent to 86 percent lower risk of metabolic syndrome.

These lower risks were seen with a number of important factors taken into account - including the women’s weight, exercise levels and the presence of any metabolic syndrome components before pregnancy.

It is not yet clear why breastfeeding itself might lower a woman’s chances of developing risk factors for diabetes and heart disease.

Abdominal obesity is one of the components of metabolic syndrome, and excess weight is closely linked to type 2 diabetes. But while it’s widely thought that breastfeeding aids post-pregnancy weight loss, weight changes did not explain the benefits seen in this study, Gunderson said.

Breastfeeding may help women shed a few extra pounds in the months after giving birth, the researcher noted, but there may be other metabolic effects that explain the lower risk of metabolic syndrome.

Breastfeeding may, for example, have positive effects on blood sugar levels, body fat mass or how fat is distributed throughout the body.

Whatever the reasons for the findings, Gunderson said they do suggest that breastfeeding can have “long-term health benefits” for mothers.

SOURCE: Diabetes, online December 3, 2009.