Abstract
In the 20th century, an epidemiological study called the "Seven countries study" was conducted through collaboration between seven different countries all over the world. This study indicated that people in countries which consume a lot of fat were at greater risk of dying from cardiovascular disease (J Mt Sinai Hosp NY, 1953, 20, 118-139). As a result, fat intake began to be considered bad for health. However, for epidemiological data such as this, "correlation does not imply causation." In other words, there is no direct cause and effect relationship indicated. Clinical studies with fat restriction intervention to investigate causality were implemented, but these dietary changes failed to produce any reduction in either cardiovascular disease or all-cause mortality (Open Heart 2015, 2, e000196).
An opposing hypothesis that fat intake could prevent heart disease began to be considered, and dietary intervention with increased fat intake reduced both cardiovascular disease and all-cause mortality in clinical studies. This effect was also not limited to the omega-3 polyunsaturated fatty acids used in initial studies (Circulation 2002, 105, 1897-1903). In studies conducted afterward, dietary interventions which increased either omega-6 or omega-9 polyunsaturated fatty acids also showed preventive effects for heart disease and stroke (N Engl J Med 2013, 368, 1279-1290). In addition, recent studies have even shown increases in all-cause mortality and cardiovascular disease from dietary intervention which reduces saturated fatty acids (BMJ 2013, 346, e8707) (BMJ 2016, 353, i1246).
Due to these circumstances, the United States Department of Agriculture revised its dietary guidelines, changing the fat reduction policy which had been in place for 40 years. It has become essential knowledge that the restriction of dietary fat provides no particular health benefits while increasing healthy fat intake does (JAMA 2015, 313, 2421-2422).
Although this is not limited to vegetable-based lipids, the health benefits produced by increased fat intake are now accepted as a standard element of nutrition science all over the world. I hope we can all take action together, working to spread the knowledge of this paradigm shift in nutrition and enlighten the general public.
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