Children who are breastfed for longer go on to become more intelligent, educated and successful adults, a study has found.
Researchers analysed breastfeeding data on almost 3,500 babies who were given IQ tests when they reached the age of 30 and provided information on educational attainment and income.
Bernardo Lessa Horta, from the Federal University of Pelotas in Brazil, said: “Our study provides the first evidence that prolonged breastfeeding not only increases intelligence until at least the age of 30 years, but also has an impact both at an individual and societal level by improving educational attainment and earning ability.
“What is unique about this study is the fact that, in the population we studied, breastfeeding was not more common among highly educated, high-income women, but was evenly distributed by social class.”
Participants were divided into five groups based on the length of time they were breastfed as infants.
The researchers took account of factors that might influence IQ, such as genetics, birthweight, parental schooling and whether or not the mother smoked during pregnancy.
Breastfeeding generally was found to increase adult intelligence, length of schooling and adult earnings. But the longer a child was breastfed, up to a period of one year, the greater the benefits turned out to be.
Someone who had been breastfed for at least a year gained four more IQ points, on average, at the age of 30 than a person who had been breastfed for less than a month.
He or she also had 0.9 more years of schooling and earnings that were higher by a third of the average income.
Horta added: “The likely mechanism underlying the beneficial effects of breast milk on intelligence is the presence of long-chain saturated fatty acids (DHAs) found in breast milk, which are essential for brain development.
“Our finding that predominant breastfeeding is positively related to IQ in adulthood also suggests that the amount of milk consumed plays a role.”
The research is published in The Lancet Global Health journal.