Mothers who choose to breastfeed can significantly lower their long-term risk of a dangerous cluster of heart disease risk factors known as metabolic syndrome. The new findings come from a study recently published in the online journal Diabetes.

Erica P. Gunderson, PhD, of Kaiser Permanente in Oakland, Calif., and her colleagues, found that women who had not experienced pregnancy-related diabetes, also known as gestational diabetes, lowered their risk of developing metabolic syndrome by 39 percent by breastfeeding for one to five months.

In addition, women having had gestational diabetes, and who breastfed their babies, decreased their risk of the syndrome by 44 percent.

The study showed that the longer a mother continued to breastfeed, the more her long-term health benefited. In fact, breastfeeding for longer than nine months reduced the risk of metabolic syndrome by some 86 percent in women with gestational diabetes, while for women without gestational diabetes, the risk was decreased by 56 percent.

Lead author, Erica Gunderson, an epidemiologist and research scientist at the Oakland-based Kaiser Permanente Division of Research, acknowledged, "Breastfeeding has favorable health benefits for women as well as for children. Breastfeeding may help protect women from heart disease and diabetes in the future."

The U.S. Department of Health and Human Services has established that for women, breastfeeding may lower the risk of developing type 2 diabetes, breast cancer, ovarian cancer and postpartum depression.

For children, the health benefits of breastfeeding include a reduced risk of respiratory illnesses, asthma, ear infections, stomach problems, and skin allergies, as well as a decreased risk of diabetes and sudden infant death syndrome (SIDS).

According to the American Heart Association, Metabolic syndrome is caused by being overweight, or becoming obese, in combination with physical inactivity, and certain genetic factors.

The syndrome is characterized by the occurrence of a cluster of cardiac risk factors including abdominal obesity, blood fat disorders that include low levels of HDL, (good) cholesterol, high levels of LDL (bad) cholesterol, and high triglycerides, insulin resistance or glucose intolerance, high blood pressure, a tendency for blood to clot, and elevated markers of inflammation.

Having metabolic syndrome increases the likelihood of developing heart disease and type 2 diabetes.

During the multi-center study, the researchers followed about 1,400 women who had never been pregnant, and none of whom had metabolic syndrome, to assess what factors increase the risk of coronary artery disease.

Beginning in 1985, at the start of the analysis, the study participants were examined. Follow-up examinations were also conducted at 7, 10, 15 and 20 years after the study began.

A total of 704 participants gave birth during the study period. Of these, 84 developed gestational diabetes.

Over the years of study follow-up, a total of 120 women developed metabolic syndrome. Of those, the average length of breastfeeding was determined to be 2.6 months.

Those women who did not develop metabolic syndrome were shown to have bred fed for an average of seven months.

Regarding the results, Gunderson said, "We found a very strong protective effect for lactation, and longer duration is associated with a greater risk reduction." Regarding possible reasons for the protective effects of breastfeeding, she theorized, "Pregnancy may have some adverse effects on some of these cardiovascular risk factors, and lactation (breastfeeding) may offset some of these effects."

Gunderson went on to explain that breastfeeding is associated with a faster loss of pregnancy weight, but noted that this is only "a little bit of the explanation." She noted that another part of the explanation could be that breastfeeding might minimize a woman's accumulation of belly fat, which is associated with the risk of type 2 diabetes.

Gunderson also acknowledged that breastfeeding assists in the metabolism of blood sugar, which may lower their levels of insulin.

Gunderson concluded that women who would like to reduce their risk of metabolic syndrome should eat healthy, exercise regularly, and consider breastfeeding if they choose to have a baby. She said, "Lactation is potentially something that could have a benefit to your own health."