BREAST MILK REVEALS A CORRELATION BETWEEN DIETARY FATS AND ACADEMIC SUCCESS
You are what you eat,
the saying goes, and now a study conducted by researchers at UC Santa Barbara
and the University of Pittsburgh suggests that the oft-repeated adage applies
not just to physical health but to brain power as well.
In a paper published
in the early online edition of the journal Prostaglandins, Leukotrienes
and Essential Fatty Acids, the researchers compared the fatty acid profiles
of breast milk from women in over two dozen countries with how well children
from those same countries performed on academic tests.
Their findings show
that the amount of omega-3 docosahexaenoic acid (DHA) in a mother's milk --
fats found primarily in certain fish, nuts and seeds -- is the strongest
predictor of test performance. It outweighs national income and the number of
dollars spent per pupil in schools.
DHA alone accounted
for about 20 percent of the differences in test scores among countries, the
researchers found.
On the other hand, the
amount of omega-6 fat in mother's milk -- fats that come from vegetable oils
such as corn and soybean -- predict lower test scores. When the amount of DHA
and linoleic acid (LA) -- the most common omega-6 fat -- were considered
together, they explained nearly half of the differences in test scores. In
countries where mother's diets contain more omega-6, the beneficial effects of
DHA seem to be reduced.
"Human
intelligence has a physical basis in the huge size of our brains -- some seven
times larger than would be expected for a mammal with our body size," said
Steven Gaulin, UCSB professor of anthropology and co-author of the paper.
"Since there is never a free lunch, those big brains need lots of extra
building materials -- most importantly, they need omega-3 fatty acids,
especially DHA. Omega-6 fats, however, undermine the effects of DHA and seem to
be bad for brains."
Both kinds of omega
fat must be obtained through diet. But because diets vary from place to place,
for their study Gaulin and his co-author, William D. Lassek, M.D., a professor
at the University of Pittsburgh's Graduate School of Public Health and a
retired assistant surgeon general, estimated the DHA and LA content -- the good
fat and the bad fat -- in diets in 50 countries by examining published studies
of the fatty acid profiles of women's breast milk.
The profiles are a
useful measure for two reasons, according to Gaulin. First, because various
kinds of fats interfere with one another in the body, breast milk DHA shows how
much of this brain-essential fat survives competition with omega-6. Second,
children receive their brain-building fats from their mothers. Breast milk
profiles indicate the amount of DHA children in each region receive in the
womb, through breastfeeding, and from the local diet available to their mothers
and to them after they are weaned.
The academic test results
came from the Programme for International Student Assessment (PISA), which
administers standardized tests in 58 nations. Gaulin and Lassek averaged the
three PISA tests -- math, science and reading ability -- as their measure of
cognitive performance. There were 28 countries for which the researchers found
information about both breast milk and test scores.
"Looking at those
28 countries, the DHA content of breast milk was the single best predictor of
math test performance," Gaulin said. The second best indicator was the
amount of omega-6, and its effect is opposite. "Considering the benefits
of omega-3 and the detriment of omega-6, we can get pretty darn close to
explaining half the difference in scores between countries," he added.
When DHA and LA are considered together, he added, they are twice as effective
at predicting test scores as either is alone, Gaulin said.
Gaulin and Lassek
considered two economic factors as well: per capita gross domestic product (a
measure of average wealth in each nation) and per student expenditures on
education. "Each of these factors helps explain some of the differences
between nations in test scores, but the fatty acid profile of the average
mother's milk in a given country is a better predictor of the average cognitive
performance in that country than is either of the conventional socioeconomic
measures people use," said Gaulin.
From their analysis,
the researchers conclude that both economic wellbeing and diet make a
difference in cognitive test performance, and children are best off when they
have both factors in their favor. "But if you had to choose one, you
should choose the better diet rather than the better economy," Gaulin
said.
The current research
follows a study published in 2008 that showed that the children of women who
had larger amounts of gluteofemoral fat "depots" performed better on
academic tests than those of mothers with less. "At that time we weren't
trying to identify the dietary cause," explained Gaulin. "We found
that this depot that has been evolutionarily elaborated in women is important
to building a good brain. We were content at that time to show that as a way of
understanding why the female body is as evolutionarily distinctive as it
is."
Now the researchers
are looking at diet as the key to brain-building fat, since mothers need to
acquire these fats in the first place.
Their results are
particularly interesting in 21st-century North America, Gaulin
noted, because our current agribusiness-based diets provide very low levels of
DHA -- among the lowest in the world. Thanks to two heavily
government-subsidized crops -- corn and soybeans -- the average U.S. diet is
heavy in the bad omega-6 fatty acids and far too light on the good omega-3s,
Gaulin said.
"Back in the
1960s, in the middle of the cardiovascular disease epidemic, people got the
idea that saturated fats were bad and polyunsaturated fats were good," he
explained. "That's one reason margarine became so popular. But the
polyunsaturated fats that were increased were the ones with omega-6, not
omega-3. So our message is that not only is it advisable to increase omega 3
intake, it's highly advisable to decrease omega-6 -- the very fats that in the
1960s and '70s we were told we should be eating more of."
Gaulin added that
mayonnaise is, in general, the most omega-6-laden food in the average person's
refrigerator. "If you have too much of one -- omega-6 -- and too little of
the other -- omega 3 -- you're going to end up paying a price
cognitively," he said.
The issue is a huge
concern for women, Gaulin noted, because "that's where kids' brains come
from. But it's important for men as well because they have to take care of the
brains their moms gave them.
"Just like a
racecar burns up some of its motor oil with every lap, your brain burns up omega-3
and you need to replenish it every day," he said.
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