So why is it that the rate of heart disease among men living in
Japan is less than half that of men living in the U.S. and that Japanese men
tend to have less artherosclerosis -- the artery-clogging plaque that leads to
heart attacks and strokes?
A new study suggests that the answer may be found in the sea.
Because they ate more fish, men living in Japan who participated in the
study had twice the levels of omega-3 fatty acids in their blood as white men
and Japanese men living in the U.S. They also had less severe degrees of
The finding lends support to the hypothesis that omega-3, which is found
primarily in fatty fish like tuna, mackerel, and salmon, protects against
plaque buildup in the arteries.
Sources of omega-3 fatty acids are fish oils, which contain docosahexaenoic
acid (DHA) and eicosapentaenoic acid (EPA), and plant sources. Alpha-linolenic
acid (ALA), which is converted into omega-3 fatty acids in the body, is a
plant-source omega-3 fatty acid.
Studies have generally used fish oils. While plant sources with ALA may have
the same benefits, less is known about them.
"The extremely high intake of fish in Japan may explain the much lower
rate of atherosclerosis and subsequent coronary heart disease," researcher
Akira Sekikawa, MD, PhD, tells WebMD. "This study does not prove that
omega-3 is protecting these men, but we showed that artery thickness decreased
as omega-3 levels went up."
The Japanese diet has become increasingly
westernized since the end of World War II, but fish consumption in Japan is
still among the highest in the world.
People in Japan eat an average of 3 ounces of fish every day, while the
average American finds it difficult to manage the two servings of fish a week
recommended for heart health by the American
Heart Association, omega-3 researcher William Harris, PhD, tells WebMD.
He adds that the average omega-3 intake in Japan of 1 gram a day is about
eight times higher than the amount the typical American gets.
"We are not a nation that loves fish, and that isn't likely to
change," he says. "But it is increasingly clear that we need to get
more omega-3 into our diets."
Fish oil supplements are one way of
doing this. Studies in individuals with heart disease have shown a benefit of
supplemental omega-3 fatty acids. Based on these studies, the American Heart
Association recommends that people with heart disease take 1 gram of EPA plus