Researchers compared the fatty acid profiles of breast milk from women in over two dozen countries with how well children from those same countries did 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,” says Steven Gaulin, professor of anthropology at University of California, Santa Barbara, and coauthor 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.”