Breast milk content may affect child's obesity risk

NEW YORK (Reuters Health) - Mothers who breast feed and have high levels of a protein secreted by lipids in their milk may be increasing the risk that their child will be overweight, German researchers report.

Dr. Maria Weyermann of The German Cancer Research Center in Heidelberg and her colleagues found that a child's likelihood of being overweight by age 2 rose with the amount of adiponectin in his or her mother's milk.

The significance of these findings remain unclear, Dr. Matthew W. Gillman and Dr. Christos S. Mantzoros, Harvard Medical School, Boston, point out in an editorial accompanying the study, because infants may not be able to absorb the adiponectin contained in breast milk.

Also, they add, high levels of adiponectin in adults actually reduce heart disease and diabetes risk, making it "counterintuitive" that high levels would contribute to excess weight in children.

The jury is still out on whether nursing does protect children from becoming overweight, Weyermann and her team add.

The researchers investigated how breast-feeding might influence obesity risk by looking at adiponectin and another protein secreted by fat cells, leptin, which regulates appetite as well as the body's use of energy from food.

Adiponectin is involved in metabolism of fats and sugars. The fetus and placenta produce both proteins at high levels, the researchers point out, raising the possibility that they play a role in fetal development.

The levels of both proteins were measured in the breast milk of the mothers of 674 children when the infants were six weeks old. Among the children who were breast-fed for at least six months, obesity risk rose in tandem with breast milk adiponectin levels. However, leptin levels showed no association with whether or not a child would be overweight.

"Our data provide evidence that the possible protective effect of breast-feeding against childhood obesity might depend, at least in part, on low levels of breast milk adiponectin," Weyermann and her team write.