Breastfeeding, early nutrition, and adult body fat.

Objective: To examine the association between breastfeeding and adult body fatness, adjusting for nutritional intake in early childhood.

Study Design: Nutritional intakes of 73 healthy infants born in 1984 who participated in the 2-decade-long Longitudinal Study of Nutrition and Growth in Children (Etude Longitudinale Alimentation Nutrition Croissance des Enfants [ELANCE]) were estimated at age 10 months and again at age 2 years. Breastfeeding was defined as any breastfeeding, including partial breastfeeding, regardless of duration. At age 20 years, weight, height, subscapular skinfold thickness (SF), and fat mass (assessed via bioelectrical impedance analysis) were measured.

Results: In this sample, 64% of the children had been breastfed. In linear regression models adjusted for mother's body mass index and father's profession, breastfeeding was not associated with any of the body fat measurements at 20 years (all P > .05). After adding nutritional intake variables (total energy and % energy from nutrients) to the models, breastfeeding became significantly associated with lower SF at 20 years. In particular, breastfed subjects had significantly lower % SF at 20 years after adjustment for energy and % fat intakes at 2 years of age, (β = -28.25% SF; 95% CI, -50.28% to -6.21%; P = .013) or when adjusting for energy and % carbohydrates at 2 years of age (β = -28.27% SF; 95% CI, -50.64% to -5.90%; P = .014).

Conclusion: Breastfeeding was not associated with adult body fatness taking into account the usual confounding factors. However, after also adjusting for nutritional intake covariates, a protective effect of breastfeeding emerged. Early nutrition needs to be taken into account when examining the long-term health effects of breastfeeding.