The Pacific island nation of Japan has lower rates of cardiovascular disease than nearly every other country on earth. Since the 1950s, doctors and epidemiologists have studied Japanese culture, seeking to unlock the reason for the this positive heart health. Several aspects of the Japanese diet, including an emphasis on fish and soybeans, are credited with reducing the number and severity of heart attack incidences in Japan.
History
In the late 1950s, an oceanographer-turned-physiologist Ancel Keys noticed that the rate of heart attacks in different regions of the world varied widely as did the amount of fat that people in those different regions consumed daily. The lowest heart attack rates in the world were found in Crete, where the inhabitants ate unsaturated fats such as olive oil. Heart attack rates in Japan were also extremely low, where the diet was very low in fat. In 1959, Keys published a food book called "Eat Well and Stay Well," espousing a diet low in saturated fats based on his observations of the relationship between diet and heart attack incidences.
Long-Term Study
In the 1950s, Keys began the multinational Seven Countries Study to track both diet and cardiovascular disease epidemiology for the long term. Rural populations espousing traditional diets were chosen in all seven countries, including two prefectures of Japan, according to the University of Minnesota. The study continued through extensive reports in the 1980s, and continued at the time of publication tracking the mortality rates of the reporting subjects. Only Greece had lower levels of coronary disease, though the subjects in Japan smoked at the same rates as found in Western countries and also had similar blood pressure.
Fish
The omega-3 levels in bloodstreams of Japanese men were twice that of similarly-aged American men, according to an American College of Cardiology study in 2008 reported on ScienceDaily.com. A diet high in omega-3, like sardines, tuna and salmon, is the most likely source of this artery-protecting compound. Omega-3 lowers blood pressure, reduces atherosclerosis, lowers triglycerides and guards against heart attack, according to MayoClinic.com. A field trial in Japan with more than 18,000 subjects was conducted in 2009 to specifically examine the effect of omega-3 EPA, a component of fish oil, reports the University of Connecticut's Omega-3 Learning and Education Consortium. The study concluded that omega-3 EPA supplements reduced both heart attack risk and severity by about 19 percent.
Soy
While fish is the element of the Japanese diet receiving the most publicity regarding lowering the heart attack rate, it is not the only heart-healthy component of the traditional Japanese diet. Soy consumption also helps reduce the risk of cardiovascular disease as well as the risk of certain cancers, reported Chisato Nigata of the Department of Public Health at the Gifu University School of Medicine in the April 2000 International Journal of Epidemiology. A survey of dietary habits in more than 6,000 households, together with information from vital statistics records and a 5-year nutritional study, were compared to discern the correlation between soy intake, cancer mortality and heart disease. The author concluded that the analysis supported the proposition that soy helps protect against stomach cancer and heart disease, especially for women.
References
- "International Journal of Epidemiology"; Ecological study of the affiliations between soy product intake and mortality from cancer and heart disease in Japan; Chisato Nigato; April 2000
- "University of Connecticut Omega-3 Learning for Health and Medicine"; The omega-3 fatty acid EPA and coronary events
- University of Houston: Engines of our Ingenuity
- University of Minnesota; Preventing Heart Attack and Stroke: A History of Cardiovascular Disease Epidemiology; Seven Countries Study in Japan; Noboru Kimura
- "ScienceDaily"; Japanese Diet Rich in Fish May Hold Secret to Healthy Heart: Omega-3 Fatty Acids From Fish Appear to Prevent Clogged Arteries; July 29, 2008
- MayoClinic: Omega-3 fatty acids, fish oil, alpha-linoleic acid
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