Breast-fed infants have higher leptin values than formula-fed infants in the first four months of life

Background: Leptin is a hormone present in breast milk, which regulates food intake and energy metabolism. Aim: To investigate whether leptin levels are different in breast-fed (BF) or formula-fed (FF) infants in the first months of life. Methods: We evaluated serum leptin by radioimmunoassay and anthropometric parameters in 51 infants at the average age of 62.8 +/- 30 days, 25 exclusively BF and 26 exclusively FF. Results: Leptin serum values were higher in BF (7.1 +/- 10.4 ng/ml) than in FF (3.7 +/- 3.87 ng/ml) infants (p <0.05). Leptin values were higher in females (6.9 +/- 9.87 ng/ml) than in males (3.5 +/- 3.88 ng/ml) (p <0.05). No differences were found in anthropometric measurements and body mass index. Conclusion: The kind of feeding might be a factor affecting serum leptin concentration in term infants. The long-term consequences of this difference between BF and FF infants and leptin's role in promoting obesity later in life are unknown.