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Fact Buster

Q: Are breastfed babies smarter?

A: Research suggests breastfed babies have marginally higher IQs, but it's not entirely clear this is due to breastmilk.

Our expert: Professor Michael Kramer & Professor Wendy Oddy

breastfeeding_300x150iStockPhoto | Vesna Andjic

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It's not called liquid gold for nothing. Breastmilk is largely considered the best food for babies and both the World Health Organization (WHO) and Australia's National Health and Medical Research Council recommend newborns be breastfed exclusively for their first six months.

The nutritional and health benefits of breastfeeding for newborns are largely undisputed, with evidence suggesting breastmilk boosts the immune system, protects against a raft of common childhood infections, as well as asthma and allergies, and even helps prevent obesity later in life. (Check out the National Health and Medical Research Council's Infant Feeding Guidelines for a comprehensive review of the evidence for breastfeeding.)

But what about the research into the cognitive benefits of breastfeeding, especially that which suggests breastfed babes go on to have higher IQs when compared to their formula fed friends. Does it measure up?

What does the evidence say?

Whether the evidence is strong enough to prove that breastfeeding is directly linked to a higher IQ is the subject of significant debate. This is largely because it's difficult for researchers to filter out the myriad of factors other than breastfeeding, which many breastfed babies are exposed to, that could potentially influence a child's IQ. These factors include the mother's IQ and level of education, home environment, family income, or simply how the mother interacts with the child.

"It is hard to control for these factors [when conducting research] but many observational studies have successfully done so and found robust effects – there are very few studies that have not found an effect," says paediatrician and adviser to the WHO Professor Michael Kramer.

When researchers from Harvard compared breastfed and formula fed babies they found for each additional month a child was breastfed they had better language skills at 3 years old and higher IQ scores at age 7. This is after taking into consideration the effects of a mother's intelligence and the child's home environment. Breastfeeding an infant for the first year of life would increase IQ by about 4 points, their findings showed.

Another study by nutritional epidemiologist Professor Wendy Oddy from the Telethon Kids Institute in Perth took into account maternal education and age, family income and the interaction of breastfeeding.

"We found that babies who were breastfed for more than six months had mean verbal IQ scores almost four points higher at age 6 than children who were never breastfed," says Oddy.

Kramer's own widely cited 2001 study put mothers who attended hospitals and clinics into two groups, one was encouraged to prolong breastfeeding and the other wasn't offered any advice. He found on average the children in the group whose mothers were encouraged to continue feeding had a higher IQ at the age of 6-and-a-half when compared to those in the other group.

"I don't think the study proves cause and effect, but in line with the many observational studies the evidence is pretty rock solid," Kramer says.

"The evidence is much more so than many other touted benefits of breastfeeding like asthma, allergies, obesity, and heart disease," says Kramer who has studied the effects of breastfeeding in some of these areas.

A magic ingredient?

For Oddy, it makes perfect sense that breastmilk plays a role in the cognitive development of babies. For starters, it's rich in omega-3 fatty acids that are essential for brain development, 75 per cent of which occurs in the first two years of a child's life.

"Breastmilk is a live bioactive fluid that has evolved with the human species over millions of years for the optimum development of the baby," says Oddy.

What's still not clear is whether the boost in IQ is due to the breastmilk itself or the physical and social interactions that are part and parcel of breastfeeding.

But Kramer points to an older study on pre-term infants that suggests there's something contained in the breastmilk itself that has cognitive benefits. In this study pre-term infants tube fed breastmilk were found to have a higher IQ at age 8 when compared to others who had been fed formula by the same means.

But in general he admits it "might also be the physical and emotional contact or the fact that it takes longer to breastfeed a child and the baby hears more words during that time than if he or she were bottle feeding".

Oddy agrees that it's difficult to know for certain where the cognitive benefits stem from.

"It's quite difficult to separate out the effects of bonding because breastfeeding does elicit love hormones like oxytocin," she says.

How many IQ points?

If you're expecting breastfeeding to deliver a mini Einstein prepare to be disappointed, as the degree to which breastfeeding affects IQ is pretty modest according to Kramer.

"The size of the effect is on average 3 or 4 IQ points, which is about the same magnitude as you would find in a first born compared to subsequent children," says Kramer.

"Smarter kids will be a little smarter, dumb kids will be less dumb, and average kids will be a little less average."

"The only difference is the mother can offer this benefit to all of her children instead of just the first one," he says.

Also Kramer points out there are many different ways to stimulate a child's cognitive development.

"Playing with a child, talking to a child, reading to a child, good nutrition, using seatbelts, physical activity, not smoking can all stimulate a child's cognitive development," he says.

Professor Michael Kramer is a paediatrician at McGill University Montreal in Canada and adviser to the WHO, and Professor Wendy Oddy is a nutritional epidemiologist at the Telethon Kids Institute in Western Australia. They spoke to Nicola Garrett.

Published 24/09/2014

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