By Don Rauf
Many studies have shown that eating fish can be good for the heart. To have a protective effect, however, fish consumption may have to be higher than once thought.
Omega-3 fatty acids benefit the hearts of healthy people and those at risk of cardiovascular disease, according to the American Heart Association.
New research has found that if fish oil is to have a significant positive effect on the heart, people may have to increase their fish consumption to levels comparable to those of people living in Japan.
Akira Sekikawa, MD, associate professor of epidemiology at University of Pittsburgh Graduate School of Public Health, led this study reviewing data on 175 Japanese men and 113 white men, who were ages 40 to 49 at the start of the investigation.
The authors of this study noted that coronary heart disease rates in Japan are uniquely low compared to those in US and many other developed countries.
The goal of these researchers was to determine if higher concentrations of omega-3 fatty acids, called long chain n-3 polyunsaturated fatty acids (LCn3PUFAs) made a difference in rates of coronary artery calcification (CAC) between Japanese men in Japan and white men in the US.
CAC occurs when calcium gradually builds up in the inner lining of the arteries and forms layers of plaque that can eventually lead to heart disease.
Partnering with scientists in Japan, Philadelphia and Hawaii, Dr. Sekikawa and his team followed multiple cardiovascular health factors in these subjects, including cholesterol levels, high blood pressure, diabetes rates, smoking and alcohol consumption.
After about five years of follow-up, these scientists observed that the measure of LCn3PUFAs was more than double in the Japanese men compared to the white men, while the CAC rate was three times greater in white men compared to the Japanese.
Dr. Sekikawa ruled out genetic factors, saying that CAC levels were actually higher in Japanese Americans compared to the rest of the US population.
The American Heart Association currently recommends eating at least two servings of fish per week, especially fatty fish such as salmon, mackerel, herring, lake trout, sardines and albacore tuna.
The researchers said, however, that the average American is only getting 7 to 13 grams of fish per day, or about one serving per week, while Japanese people living in Japan are eating one and a half servings per day (about 100 grams), which equals more than 10 servings per week on average.
“Previous studies investigated substantially lower intake of omega-3 fatty acids than what people in Japan actually get through their diet,” said Dr. Sekikawa in a press release. “Our study seems to indicate that the level of marine-derived omega-3 fatty acids consumed must be higher than previously thought to impart substantial protection.”
He added, “I am not encouraging Americans to start consuming massive amounts of fish, which may have harmful contaminants, such as mercury, in their flesh. However, our findings indicate that it is worthwhile to take another look at the effect of marine-derived omega-3 fatty acids on heart disease, particularly when consumed at higher rates than previously investigated.”
This study was published March 6 in the journal Heart. The research was supported by grants from the National Institutes of Health and the Japanese Ministry of Education Culture, Sports, Science and Technology.