Why do middle-aged men in Japan have fewer problems with clogged arteries? Why is it that the rate of heart disease among men in Japan is less than half that of men living in the US?

Because they eat more oily fish, which contains omega 3 fatty acids, a new study suggests. The research, published in the Journal of the American College of Cardiology, found that men who participated in the study had twice the blood levels of omega-3 fatty acids and lower levels of atherosclerosis compared to Japanese men or white men living in the US.

Omega-3 fatty acids, which are found in fatty fish like tuna, mackerel, and salmon, appear to protect Japanese men against clogged arteries. A fish died could have “a very substantial impact on coronary heart disease,” the researchers suggested.

In their study, researchers recruited 868 randomly selected men aged 40 to 49. 281of them 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. All study participants had a physical examination, completed a lifestyle questionnaire, and had standard blood tests to evaluate cardiovascular health. Researchers used techniques to measure the level of cholesterol build-up in the arteries, as well as tests to measure levels of fatty acids and the omega 3 fatty acids found in fish oils, that contain docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA).

People in Japan eat an average of 3 ounces of fish every day, while the average American eats fish perhaps twice a week. The average omega-3 intake in Japan of 1 gram a day is about eight times higher than the amount the typical American gets.

“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, told 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.”

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

Further research is also needed to test whether long-term, high-dose omega-3 fatty acid could lower coronary heart disease rates, researchers said. The researchers said that the study may have been limited by its relatively small sample size.

Previous studies suggest that that omega-3s can also help with major depression, schizophrenia, and postpartum depression. Eating fish is also a good way to improve brain power. Researchers from UCLA found that healthy fish oil can reduce chances of developing Alzheimer’s. Omega-3 fatty acid docosahexaenoic acid (DHA), which is found in fish oil, raises the production of LR11. LR11 is a protein which exists at excessively low levels among Alzheimer’s disease patients. LR11 is known to destroy the protein that forms the plaques linked to the disease.

Fish oil and its significant component, omega-3 fatty acids – the “good fats” that help maintain optimal brain function – have been a bastion of alternative health practitioners for years and have been sanctioned by the American Heart Association to decrease the chances of developing cardiovascular disease.