Researchers from Oxford and Essex universities have found that babies who were breastfed – even for only a short period of around four weeks – grew up to be better at reading, writing and maths at every stage of their development, according to a report in today’s press.

Sophie Borland reported that a study of more than 10,000 children, which had assessed them at the ages of five, seven, 11 and 14, examined whether there was a “true causal link” between breast-feeding and the nurturing of “brighter children”.

The survey was carried out by a team from the Institute for Social and Economic Research (ISER) at Essex University and other researchers from Oxford. Ms Borland also noted that Britain had a poor record for breastfeeding, with only 20% of new mothers never attempting it, and only 3% using their natural milk for the recommended six months.

She added that latest studies also showed that, as well as providing babies with vital nutrients, breast milk had also been shown to protect mothers from both breast and ovarian cancer in later life. While breast milk has long been known to boost babies’ immunity, helping them fight ear infections, stomach bugs and even asthma, little was known about its effects on intelligence until now.

One of the paper’s co-authors, Maria Iacovou, a social scientist at ISER said that while the health benefits of breast milk were widely known and understood, it had been less clear to what extent there were benefits for cognitive development.

“The issue was that while it looked as though breast feeding did have an impact on cognitive development, no one knew if that was just because the type of mother more likely to breastfeed in the first place was more likely to nurture brighter children, or whether there was a true causal link,” she said.

The ISER study – a working paper that will be peer-reviewed at a later date – compared breastmilk-fed children with formula-fed “twins”, children who were equivalent in all other observable respects. “We did find there is a link [between breast milk and cognitive development],” said Iacovou. “Breast milk has well-known health benefits and now we can say there are clear benefits for children’s brains as well.”