부산대학교 도서관

Childhood obesity has been increasing for decades in many countries and represents an important challenge for public health worldwide. Most factors associated with obesity act very early in life, from conception through pregnancy and infancy. Among these factors, breastfeeding has been widely studied. Six systematic reviews have analysed the association between breastfeeding (initiation, exclusivity and duration) and obesity. All these reviews reach similar conclusions: there is a dose-response negative association between breastfeeding and obesity, even after controlling for known confounders. It is difficult, however, to come to firm conclusions; the reviews are based on observational cross-sectional and longitudinal studies using different methods to determine breastfeeding rates and different definitions of obesity with different growth references. In addition, it is impossible to exclude the effect of unknown confounding. Yet, other studies published afterwards confirm the association, including a study in twins. The only study with different results, a cluster randomised controlled trial carried out for other purposes, reported no difference in BMI and adiposity at 6.5 years of age in a sample of children with different duration and exclusivity of breastfeeding; the analysis, however, did not include non breastfed or formula fed children. The negative association between breastfeeding and obesity is biologically plausible; several behavioural and nutritional mechanisms have been proposed to support the hypothesis of a causal link. Overall, and despite the need to fill some knowledge gaps with further research, it is generally accepted that interventions to protect, promote and support breastfeeding will help prevent obesity and contribute to curbing the present epidemic, as reflected in policies and strategies recommended by different agencies and governments worldwide.