A new study supports human milk as the optimal first food for babies, but the study raises questions about whether breast milk protects children from becoming obese.

The Cincinnati Children's Medical Center review of more than 80 relevant breastfeeding studies that were conducted over a period of at least 20 years is published in Current Obesity Reports.

"The best observational evidence up to now suggests that exclusively breastfeeding, or at least breastfeeding for a longer time, is associated with a 10 to 20 percent reduction in in childhood," says Jessica Woo, PhD, a researcher at Cincinnati Children's and a co-author of the study. "Research conducted recently, however, suggests that by understanding the mechanisms of how breastfeeding and the composition of human milk affect infant development, we may be able to generate a more nuanced view of the connection between breastfeeding and ."

Dr. Woo and her colleague at Cincinnati Children's, Lisa Martin, PhD, suggest three potential biological factors related to breastfeeding that may influence obesity later in life: the role of , the effect of breastfeeding on how the digestive system processes food, and how breastfeeding may influence the risk of through alterations in taste preferences and diet.

"The complex nature of the relationship between breastfeeding and obesity, including the fact that and milk production vary among women, suggests that the medical literature does not promote breastfeeding as a frontline strategy to prevent obesity," says Dr. Martin.