For years, research has suggested breastfeeding is best for babies. Now, a long-term study is backing up that theory.
According to the BBC, researchers in Brazil found infants who were breastfed over a longer period of time end up with a higher level of intelligence. They say the proof is in higher IQ scores and the number of people sampled in the study.
"This study, however, looks at a number of other factors including education achievement and income at age 30 which, along with the high sample size, makes this study a very powerful one," said Dr. Colin Michie, chairman of the Royal College of Pediatrics and Child Health's nutrition committee.
The findings, published in The Lancet Global Health, suggest other factors other than breastfeeding can contribute to a person's level of intelligence and amount of money they make over their career.
Doctors say breast milk is rich in long-chain saturated fatty acids which are necessary for brain development. Other experts say it can help a baby's immune system.
"Public Health England's advice remains that exclusive breastfeeding for around the first six months of life provides health benefits to babies," said Kevin Fenton, national director of health and well being with Public Health England.
The long-term study traced nearly 3,500 babies from all walks of life. It also found breast-fed babies were more likely to earn a higher wage and to have completed more schooling.
While the results sound promising, critics say more research is needed to confirm a link between breastfeeding and intelligence.