According to a long-term Brazilian study, there is link between breastfeeding and intelligence.

Children who are breast-fed for longer go on to become more intelligent, educated and successful adults, the study has found.

Researchers analyzed 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.

The research found those who had been breastfed for longer went on to score higher on IQ tests as adults.

Experts say the results, while not conclusive, appear to back current advice that babies should be exclusively breastfed for six months.

However, they say mothers should still have a choice about whether or not to do it.

Regarding the findings – published in The Lancet Global Health – specialists stress there are many different factors other than breastfeeding that could have an impact on intelligence, although the researchers did try to rule out the main confounders, such as mother’s education, family income and birth weight.

Dr. Bernardo Lessa Horta, from the Federal University of Pelotas in Brazil, said his study offers a unique insight because in the population he studied, breastfeeding was evenly distributed across social class – not something just practiced by the rich and educated.

Most of the babies, irrespective of social class, were breastfed – some for less than a month and others for more than a year.

Those who were breastfed for longer scored higher on measures of intelligence as adults.

They were also more likely to earn a higher wage and to have completed more schooling.

Dr. Bernardo Lessa Horta believes breast milk may offer an advantage because it is a good source of long-chain saturated fatty acids which are essential for brain development.

However, experts say the study findings cannot confirm this and that much more research is needed to explore any possible link between breastfeeding and intelligence.