THURSDAY, Oct. 16, 2003 (HealthDayNews) -- Large-scale studies in Brazil and Britain throw cold water on the theory that breast-fed children are less likely to grow into obese adults.
The studies, appearing in the Oct. 18 issue of the British Medical Journal, contradict the results of several previous reports that claimed breast-feeding reduced the incidence of obesity, at least early in life.
One widely publicized study of 15,000 children, done in 2001 by Dr. Matthew Gillman of Harvard Medical School, found that those whose mothers gave them more breast milk than formula or breast-fed them for at least six months had the lowest risk of being overweight by the time they were 9 to 14 years of age.
"We didn't find such a relationship in our study," says Leah Li, of the Institute of Child Health in London, whose research examined the effect of breast-feeding on the weight of 2,631 children between the ages of 4 and 18.
The Brazilian study tracked another 2,250 kids -- almost 80 percent of the male babies born in 1982 in the city of Pelotas -- from early in life until they enrolled in the Army at age 18 and found breast-feeding had no effect on adolescent obesity, the journal report says.
"This should not be interpreted as an argument against breast-feeding," says Dr. Cesar G. Victora, a professor of epidemiology at the Federal University of Pelotas and lead author of the report. "We have made quite a few studies of the same group of children in the early phases of life and have found benefits, including reduced mortality and reduced hospital admissions."
It's possible that there was no relationship between breast-feeding and weight, he adds, because "we went for a longer period of time, until the age of 18. The children in the other studies were young adolescents, and maybe the potential benefits disappear with age."
And his caution for American parents is that Brazil "is a different culture. It's hard to extrapolate from a developing country to a developed country."
There are no such caveats about the British report, which notes that "in both Britain and the United States, the incidence of breast-feeding has increased since 1990, but so has obesity."
The study was limited to the effects of breast-feeding on weight, Li stresses. "We didn't look at other outcomes," she says. "Breast-feeding is still important for many other reasons."
The last sentences in the two reports provide a useful summary.
"The continued protection, promotion, and support of breast-feeding remains a major public health priority," the Brazilian report says.
"Promoting breast-feeding is important, but evidence for an important beneficial effect on obesity is still equivocal," the British report says.