Mexico City (Reuters) - A diet rich in oily fish, which contains omega 3 fatty acids, may be why middle-aged men in Japan have fewer problems with clogged arteries than white men and men of Japanese descent in the United States, a study has found.
The research, published in the Journal of the American College of Cardiology, found that Japanese men living in Japan had twice the blood levels of omega-3 fatty acids and lower levels of atherosclerosis compared to middle-aged white men or Japanese-American men living in the United States,
Atherosclerosis is the buildup of plaque inside the arteries. Over time, they harden and narrow the arteries and can lead to serious problems like heart attacks and stroke.
“The death rate from coronary heart disease in Japan has always been puzzlingly low,” said Akira Sekikawa, assistant professor of epidemiology at the University of Pittsburgh, in a statement.
“Our study suggests that the very low rates of coronary heart disease among Japanese living in Japan may be due to their lifelong high consumption of fish.”
Japanese eat about 3 ounces (85 grams) of fish a day on average, while Americans eat fish perhaps twice a week. Nutritional studies show that intake of omega-3 fatty acids from fish averages 1.3 grams per day in Japan, compared to 0.2 grams per day in the United States.
Earlier studies by Sekikawa’s team showed that Japanese men had significantly less cholesterol build-up in their arteries despite similar blood cholesterol and blood pressure readings, similar rates of diabetes and much higher rates of smoking.
But it was unclear whether Japanese men were protected by strong genes, a high-fish diet or some other factor.
In this study, Sekikawa’s team recruited 868 randomly selected men aged 40 to 49. Of these, 281 were Japanese from Kusatsu in Japan, 306 were white men from Allegheny County, Pennsylvania, and 281 were third or fourth generation Japanese-Americans from Honolulu, Hawaii.
“Our study clearly demonstrated that whites and Japanese-Americans have similar levels of atherosclerosis, which are much higher than in the Japanese in Japan,” Sekikawa said.
“This indicates that much lower death rates from coronary heart disease in the Japanese in Japan is very unlikely due to genetic factors.”
Reporting by Tan Ee Lyn; editing by Robert Hart