Breast-feeding Associated With 45% Less Obesity in Japan

August 12, 2013

Yet another study, this time conducted in Japan, has shown that babies who are breast-fed have a lower risk for obesity when they are older.

At age 7 years, children who were breast-fed for 6 months were 45% less likely to be obese than those who received formula, report Michiyo Yamakawa, MHSC, from Okayama University Graduate School of Medicine and Dentistry and Pharmaceutical Sciences, Okayama, Japan, and colleagues in their study, published online August 12 in JAMA Pediatrics. The results indicate that it is important to encourage breast-feeding, even in developed countries, they note.

An accompanying editorial states that the study is "a novel and helpful addition to the literature," not least because "it is one of the first to explore the issue in an Asian population." The study adjusts for many potential confounding issues, and still the association remains strong, say editorialists Marit L. Bovberg, PhD, MS, from Oregon State University, Corvallis; Carolina Amador, MD, MPH, from Community Health Centers of Benton and Linn Counties, Corvallis, Oregon; and Adrienne E. Uphoff, IBCLC, from the School of Medicine, Virginia Commonwealth University, Richmond.

But, they wonder, would it not be better to stop spending research dollars on the breast-feeding/obesity question, given that "causality will never be proven, because it is unethical to randomize women to a formula-feeding arm"?

There is no question that "breast is best, for so many reasons," they observe. So would money not be better spent in the United States trying to improve the "abysmal job of caring for postpartum women?" they suggest. "Imagine the potential improvements in population health if we instituted a system of 'well-mother' checks… Such a system would not only prioritize breast-feeding promotion and problem solving but also would include parenting support…nutrition counseling, and other forms of preventive care."

Breast-feeding Most Protective Against Obesity

The Japanese researchers used a large nationwide data set (the Longitudinal Survey of Babies in the 21st Century) and assessed breast-feeding behavior at six months' postpartum. It included a total of 43 367 singleton children born after 37 weeks, for whom information was available with regard to feeding during infancy.

The large number of participants is a strength of the study, they note.

They add that breast-feeding rates are quite high in Japan (>20%) probably because "Japanese society has promoted breast-feeding."

Exclusive breast-feeding at 6 to 7 months of age compared with formula feeding was associated with decreased risk for overweight (adjusted odds ratio [OR], 0.85) and obesity (OR, 0.55) at age 7 years. Similar results were observed at 8 years of age.

Adjustments were made for children's factors (gender, TV-viewing time, and computer-game-playing time) and maternal factors (educational attainment, smoking status, and working status).

The researchers note that the protective associations for obesity were greater than those for overweight.

"The present finding among schoolchildren in Japan provides further evidence on the protective effect of breast-feeding," they state.

The fact that Yamakawa and colleagues report results similar to many studies that have been conducted in Europe, North America, and Australia "is reassuring," the editorialists conclude.

Neither the authors nor editorialists have reported relevant financial relationships.

JAMA Pediatr. Published online August 12, 2013. Abstract Editorial


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