Breastfeeding reduces the obesity risk in American Samoan Infants

Breastfeeding reduces the obesity risk in American Samoan Infants

Breastfeeding slowed down the weight gain in overweight/obesity prone Samoan infants

Nutrition Remarks Health News Highlights (July 24, 2013)

Written by Deeksha Sharma, Ph.D, Health News Writer for Nutrition Remarks, Solon, OH, USA

Reviewed by Dr. Hawley NL, International Health Institute, Department of Epidemiology, Brown University, Providence, Rhode Island, USA; Weight Control and Diabetes Research Center, The Miriam Hospital, Providence, Rhode Island, USA

American Samoan adults often have high body mass index and prevalent obesity. Infancy is a critical period in the development of obesity so this study examines how choice of feeding modes affects the growth trajectories of American Samoan infants. Breastfeeding is found associated with slower weight gain in these infants suggesting its protective benefits for obesity risk.

Global prevalence of obesity and associated chronic non-communicable diseases are on rise, therefore identifying potential intervention targets to stem obesity epidemic is a public health priority. American Samoans have greatest mean BMI worldwide (59% adult males (aged 18–74 years) and 71% adult females to be obese (BMI ≥32 kg m-2). This study investigate the age at which obesogenic growth trajectories are established in Samoan infants to identify the ideal age at which obesity prevention programs should be targeted. Further, growth of breast and formula-fed infants were analyzed to find out whether breastfeeding attenuates the risk of obesity in Samoans.

At birth, mean weight-for-length in both sexes was close to the median of CDC reference population. While length of these infants rose steadily throughout infancy, weight gain in early infancy occurred far more rapidly in Samoan infants than in the CDC reference. By 4 months, mean weight-for length z-scores had risen to 0.98 (84th centile) in boys and 0.76 (78th centile) in girls. Prevalence of overweight was established early, but obesity was initially low, it rose with increasing age and by 15 months, 23.3% boys and 16.7% girls were obese. The level of overweight fell from a peak of 30.5% in 4-month-old boys and 23.0% in 3-month-old girls to 16.1% and 14.0% in 15-month-old boys and girls, respectively. Combined, the prevalence of overweight and obesity peaked at 39% at 4–6 months. At 15 months of age, 35.2% of infants in American Samoa exceeded the CDC 85th percentile and were overweight or obese; 20.1% of them above 95th percentile and obese. The prevalence of obesity observed here was four times greater than the expected value. It is noteworthy that while the prevalence of obesity increased between birth and 15 months of age, after 4 months of age the prevalence of overweight decreased. This suggests that infants classified as overweight in early infancy were becoming obese over time but very few infants who remained in normal weight range at 4 months were then becoming overweight.

There were significant effects of feeding at 4 (±2 months) on weight and length. Boys who were formula-fed had a significantly faster rate of postnatal growth, gaining 1.08 kg/year and 2.33 cm/year more than breastfed boys. Mixed-fed boys also gained length significantly faster than breastfed boys (1.13 cm/year). Mixed- and formula-fed girls gained weight more rapidly than breastfed girls by 0.63 and 0.60 kg/year, respectively. In these Samoan infants formula feeding is, in boys, associated with more rapid growth in early infancy and greater overweight and obesity in late infancy. Girls who are fed a combination of breast milk and formula are at greater risk than their peers.

This could be due to, breastfeeding promotes self-regulation of energy intake by infant, mothers may also learn to recognize their infant’s hunger and satiety cues earlier, and mothers who choose to breastfeed may be those who adopt other healthy dietary and lifestyle habits. Mothers who choose to formula feed may also introduce solid foods at an earlier age, which is in itself, associated with greater weight gain during infancy and greater weight and adiposity in childhood. Further study of American Samoan infant feeding is needed to understand these postnatal growth patterns and feeding choices in context of economic and cultural modernization, especially the changing and expanding roles of women.

Comparability of these findings with other studies is difficult, largely because of the use of different references for growth. The CDC 2000 references were employed here because of their continued use in clinical practice in American Samoa and feeding characteristics of the CDC reference population were similar to those observed here.

The level of adult obesity seen in American Samoan women of childbearing age, a probable contributor to infant obesity, is likely to foreshadow the experience of other developing countries as they undergo similar economic, demographic and nutritional transition. Findings suggest that obesity prevention efforts in Samoans must be targeted at the very youngest infants with a focus on maintaining normal weight by 4 months of age. Also findings suggest that protective effects of breastfeeding for later obesity are generalizable outside of European-derived populations. Alongside other health benefits of breastfeeding, the promotion of exclusive breastfeeding may be a suitable cost-effective and sustainable intervention for the reduction of overweight and obesity risk.

This news highlight is based on the following article published by Hawley NL et al. Additional general background information was acquired from PubMed.

Hawley NL et al. The contribution of feeding mode to obesogenic growth trajectories in American Samoan infants. Pediatr Obes. 2013 Feb 5.