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 say .
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.
While the researchers have found at least one gene linking
intelligence and breast-feeding, they say 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 unravelling the human genome, Moffitt adds.
(Agencies via China Daily November 7, 2007)