A research published in the Proceedings of the National Academy of Sciences has found a gene that improves IQ in breastfed children. Having the FADS2 gene made children score, on average, 7 points more in IQ tests if they were breastfed.

The study found breastfeeding had no effect on the IQ of children with a different version. This gene, found in 90 % of the people, is known to encode enzymes involved in the metabolism of fatty acids from the food, chemicals connected with brain development. "Seven points difference is enough to put the child in the top third of the class", wrote the researchers from the Institute of Psychiatry, Kings College London.

The team employed information gathered from two previous researches on breast-feeding carried on in Britain and New Zealand, and made on over 3,000 children. The subjects' IQ was determined between the ages of 5 to 13.

The connection between intelligence and breastfeeding is a tricky one, because mothers with higher education or who come from more affluent backgrounds were more likely to breastfeed in many researches, biasing the conclusions. "The findings give a fresh perspective on the arguments by showing a physiological mechanism that could account for the difference between breastfed and bottle-fed babies. The argument about intelligence has been about nature versus nurture for at least a century. However, we have shown that in fact nature works via nurture to create better health outcomes.", said co-author Professor Terrie Moffitt.

More recently, producers added fatty acids to formula milk but their outcomes are inconsistent. "This shows for the majority of parents they can have a positive effect on their babies IQ by breastfeeding.", said Belinda Phipps, of the National Childbirth Trust.

"The study highlighted the interaction between nutrition and genetics. In this study you have an effect that suggests that nature is more important that nurture. If nine out of 10 babies benefit, then that is a very good chance. But the study did not specify how long babies were breastfed for and it may be that even breastfeeding for a short period may be beneficial for intelligence.", said Catherine Collins, a dietician at St Georges Hospital in London and spokesperson for the British Dietetic Association.