Washington, March 18 (IANS): Longer duration of breastfeeding is linked with increased intelligence in adulthood, longer schooling and higher adult earnings, finds a new study.

The effects of breastfeeding on brain development and child intelligence is well established, but whether these effects persist into adulthood was less clear.

"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," said lead author Bernardo Lessa Horta from the Federal University of Pelotas in Brazil.

The study published in The Lancet Global Health, followed a group of around 3,500 newborns for 30 years.

Horta and colleagues analysed data from a prospective study of nearly 6,000 infants born in Pelotas, Brazil in 1982. Information on breastfeeding was collected in early childhood.

Participants were given an IQ test at the average age of 30 years and information on educational achievement and income was also collected.

Information on IQ and breastfeeding was available for just over half (3,493) of the participants.

The researchers divided these subjects into five groups based on the length of time they were breastfed as infants.

While the study showed increased adult intelligence, longer schooling and higher adult earnings at all duration levels of breastfeeding, the longer a child was breastfed for (up to 12 months) the greater the magnitude of benefits.

"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," said Horta.

"Our finding that predominant breastfeeding is positively related to IQ in adulthood also suggests that the amount of milk consumed plays a role," the researcher added.