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 radio-immunoassay 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.