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24 September 2015, 06:00
Breastfeeding does little to improve a child's intelligence, despite the widespread belief that "breast is best'' for IQ, research has shown.
Scientists who conducted a study of 11,000 British children found no reliable association between breastfeeding and higher IQ at age two.
Nor was breastfeeding related to improvements in IQ after the age of two, indicating that it did not help young brains develop better over time.
The children were taking part in the Twins Early Development Study (Teds) set up to disentangle the impact of "nature and nurture'' on growing children - that is, the relative effects of genes and the environment.
Some of the twins were identical, sharing all their genes, and others non-identical. Only identical twins would be expected to respond the same way to a purely genetic influence.
Breastfeeding was associated with a small IQ advantage for girls at age two, but by 16 this had disappeared.
Writing in the online journal Public Library of Science ONE, the scientists concluded: "Breastfeeding has little benefit for early life intelligence and cognitive growth from toddlerhood through adolescence.''
Study co-leader Dr Sophie von Stumm, from Goldsmiths, University of London, said: "Many researchers have previously investigated whether being breastfed in early life benefits IQ. Such an association is plausible because long-chain polysaturated fatty acids that are present in human breast milk but not animal milk or formula enhance neurodevelopment. However, few of the earlier studies have employed strong research designs that produce reliable results.
"Children - and adults - differ in their cognitive abilities, and it is important to identify factors that give rise to these differences. But comparatively small events like breastfeeding are very unlikely to be at the core of something as big and complex as children's differences in IQ. Instead, children's IQ differences are better explained by long-term factors, for example, children's family background and their schooling.''
She stressed that breastfeeding had other benefits, such as helping to build a child's immune system, but added: "That said, mothers should be aware that they are not harming their child if they choose not to, or cannot, breastfeed. Being bottle fed as an infant won't cost your child a chance at a university degree later in life.''
A Brazilian study published in March pointed to a link between breastfeeding and intelligence. Researchers who traced nearly 3,500 babies from all walks of life found that those who had been breastfed for longer went on to gain better scores in adult IQ tests.
Janet Fyle, from the Royal College of Midwives (RCM) said: "This is another research report among many studies on breastfeeding and child outcomes. While this study adds to an already existing body of knowledge about breastfeeding, our advice remains the same, breastfeeding has many positive benefits for a child's health and well-being in both the short and longer term. We also know of its beneficial impacts on the health and well-being of the mother.''
Alison Burton, maternity and early years lead at Public Health England, said: "As the authors confirm, breastfeeding provides the best nutrition for babies and helps protect against infections. PHE's advice is to breastfeed exclusively for the first six months. We recognise that not all mothers are able to breastfeed and infant formula is the only alternative to breast milk for babies under 12 months old.''