http://news.yahoo.com/s/nm/20071105/sc_nm/breastfeeding_iq_dc;_ylt=Ags6p
zFgmu9bJNWQA9CtMECs0NUE

Gene explains why breast-feeding makes kids smarter By Michael Kahn
Mon Nov 5, 5:02 PM ET
 


A very common gene can help explain why breast-fed babies tend to grow up 
to be more intelligent than those raised exclusively on bottled milk.

Breast-fed babies who shared the genetic variant outscored bottle-fed peers 
in intelligence tests, researchers said. The variant to the FADS2 gene, 
involved in processing fatty acids, is found in about 90 percent of people, they 
added.

"For 100 years, the intelligence quotient has been at the heart of scientific 
and public debates about nature versus nurture," Terrie Moffitt of Kings 
College London and colleagues wrote in their report, published on Monday in 
the Proceedings of the National Academy of Sciences.

"Evidence that nature and nurture work together drives a nail in the coffin of 
the nature-versus-nurture debate."

The study looked at 3,200 children in Britain and New Zealand.

Breast-feeding has many advantages for children including reducing infections, 
respiratory illnesses and diarrhoea, earlier research has shown. A study 
presented at an American Heart Association meeting on Monday added 
healthier blood cholesterol levels to that list.

Although scientists have been looking at potential links between breast-
feeding and intelligence for decades, the direct relationship has not always 
been clear.

The researchers studied the FADS2 gene involved in processing omega 3 fatty 
acids found in foods such as salmon, nuts and avocados and turning them into 
nutrients for the brain.

In both countries, breast-fed children had a higher IQ by about 6 to 7 points, 
but only if they had a variant that made the gene more efficiently process 
fatty acids.

For those with the less common -- and less efficient -- variant, breast-feeding 
made no difference when it came to intelligence, the researchers said .

The researchers ruled out alternate explanations, saying the effect of FADS2 
applied equally to babies with normal and low birth weight. The effect was also 
the same no matter the mother's social class or IQ.

The team also tested the mothers' DNA and concluded that the FADS2 gene 
did not somehow alter the quality of breast milk.

"We took cells from the children and then analyzed DNA and then we compared 
how they scored on IQ tests and looked up if they were breast-fed as babies," 
Moffitt said in a telephone interview. "It was very straightforward."

While the researchers have found at least one gene linking intelligence and 
breast-feeding, they said they still need to better understand how FADS2 
processes nutrients in breast milk.

They also acknowledge that many other genes also likely have a role in 
intelligence but say their study offers a different approach to unraveling the 
human genome, Moffitt added.

(Reporting by Michael Kahn; editing by Maggie Fox and Keith Weir)

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