At a time when fat is foe, health-conscious Americans have been
purging it from their diets--or feeling guilty when they don't. But
there's one type of fat you can eat with an easy conscience: it may make
you see better, think better and even feel better.
Docosahexanoic acid (DHA) is an omega-3 fatty acid, a
substance--found naturally in oily fish such as tuna, sardines and
salmon--that scientists call the building block of the brain. Nearly 60%
of the brain is composed of fat, and a third of that matter is DHA, which
may explain why low levels of the fatty acid--also found in red meat,
eggs and vegetable oils--seem to impair a wide range of brain and bodily
functions.
A new study from the Retina Foundation of the Southwest in Dallas,
Texas, for example, has found that newborn infants fed formula without
DHA for a year had poorer sight than infants fed either breast milk,
considered to be the best source of fatty acid for infants, or
DHA-fortified formula. This is likely because DHA strengthens the brain
cells associated with eyesight.
Unfortunately, DHA levels in breast milk have fallen in the last 25
years, says Eileen Birch, Ph.D., a senior scientist at the Retina
Foundation and author of the infant study. This may be due to the
prevalence of processed foods in the American diet, like doughnuts and
white bread, which not only lack crucial omega-3 fatty acids (not to
mention other important nutrients) but also contain omega-6 fatty acids,
which cancel out the effects of omega-3s.
Other DHA research seems to prove true the old adage that fish is
"brain food." A Harvard Medical School study published last spring found
that omega-3 supplements stabilized the highs and lows of manic
depression in patients suffering from the illness, indicating that DHA
may play a role both in causing and treating that disease. Another
Harvard study found that omega-3 fatty acids could help head off heart
failure by stabilizing an erratic heartbeat.
DHA can be found naturally in food or in omega-3 fatty acid
supplements. The National Academy of Sciences suggests 660 mg daily for
healthy adults.
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