A study has found that prolonged breastfeeding is linked to higher intelligence, longer schooling and greater earnings as an adult.
The study, published in The Lancet Global Health, followed 3,493 infants born in Pelotas, Brazil. After an average of 30 years, the researchers measured their IQs and collected further information about their educational achievement and income.
"The effect of breastfeeding on brain development and child intelligence is well established, but whether these effects persist into adulthood is less clear," says lead author Dr. Bernardo Lessa Horta of Federal University of Pelotas in Brazil.
"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."
Dr. Horta believes there is a biological mechanism for the study's findings:
"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."
Although the researchers did not measure the characteristics of the infants' home environment or maternal-infant bonding, the researchers state that previous research suggests breastfed subjects have demonstrated improved cognitive functioning even after controlling for home environment and stimulation.
"Our results suggest that breastfeeding not only improves intelligence up to adulthood, but also has an effect at both the individual and societal level, by increasing educational attainment and earning ability," the authors conclude.