The researchers also confirmed the presence of leptin in human milk. Leptin is another protein produced by fat that appears to play an important role in the regulation of body fat.  Leptin is a satiety hormone, involved in the state of being "full." 

Adiponectin levels, however, are substantially greater than leptin in human milk, according to Dr. Martin, a researcher in the Center for Epidemiology and Biostatistics at Cincinnati Children's and in the Division of Human Genetics. "Whether the greater quantity of adiponectin has biological significance remains to be seen," she says.

The study will be presented May 2 at the annual meeting of the Pediatric Academic Societies in San Francisco.