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Japan's Heart-Healthy Diet: Fish Is Key

Study Shows High Omega-3 Levels in Japanese Diet Cuts Heart Disease Rates

High Omega-3 Levels continued...

Other good sources of omega-3 include foods such as flaxseed and canola oils, soybean, tofu, and walnuts. Omega-3 fatty acids are often sold as capsules but can upset the stomach and should be taken with food.

Harris is working to develop a soybean-based omega-3-enriched oil through a grant from the company Monsanto.

He believes that many of the foods we eat will soon be fortified with omega-3 in the same way that they are now fortified with folic acid and other vitamins.

"Either we get people in the U.S. to start liking oily fish, which probably isn't going to happen, or we find another way of getting it into our food," he says.

Fish Eaters Had Less Plaque

The study by Sekikawa and colleagues included 281 Japanese men living in Japan, an equal number of Japanese men living in the U.S., and 306 white men who lived in the U.S.

All the men were in their 40s, and all underwent blood testing to determine serum levels of fatty acids, including omega-3. The men also had two tests for atherosclerosis -- one measuring the thickness of the artery wall in a major neck artery that sends blood to the brain and the other measuring plaque in arteries leading to the heart.

While total fatty acid levels were similar in the three groups, blood omega-3 levels in the Japanese men living in Japan were 45% higher and 80% higher, respectively, than in Japanese men and white men living in the U.S.

And both measures of artherosclerosis showed less plaque buildup in the arteries of the Japanese men living in Japan. Atherosclerosis levels were similar in both Japanese-Americans and in white Americans.

The study appears in the Aug. 5 issue of the Journal of theAmerican College of Cardiology.

"This indicates that much lower death rates from coronary heart disease in the Japanese in Japan is very unlikely due to genetic factors," Sekikawa says.

The 'Omega-3 Hypothesis'

In an editorial accompanying the study, Harris writes that what he calls the "omega-3 hypothesis" grew from research on the Inuit Eskimos of Greenland conducted almost four decades ago.

Despite eating a diet low in fruits, vegetables, and complex carbohydrates and high in fat and cholesterol, the Eskimos had very low rates of heart disease. Researchers concluded that the reason was the incredibly high levels of omega-3 in their diets from the consumption of large amounts of fish, whale, and seal.

But recent studies suggest that heart disease rates among Alaskan Eskimos are now higher than among whites in the U.S., even though fish consumption in the population remains high.

"At least part of the problem in Alaska appears to be not a lack of omega-3 but the introduction of massive amounts of shortenings and other saturated fats into their Westernizing diet," Harris writes.

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