Trends for cardiovascular disease in Japan, and its prevention through nutritional assessment and improvement

In the 1960s, Japan had the highest mortality from stroke and the lowest mortality of ischemic heart disease (IHD) in the world. Since then, stroke mortality has decreased substantially and IHD mortality has declined moderately along with a large decline in blood pressure levels and for men a moderate decline in smoking albeit an increase in blood cholesterol levels. More recently, stroke mortality in Japan is still two-fold higher and IHD mortality is one-fourth compared with that in the US and UK. The large difference in cardiovascular disease profiles may be due to a material difference in profiles of cardiovascular risk factors, attributable to differences in diets. Higher sodium, lower calcium, and lower meat intakes, and for men higher alcohol consumption may have contributed to the higher prevalence of hypertension leading to a higher risk of stroke, while higher physical activity, higher n3 polyunsaturated fat (fish) intake, lower saturated fat (meat) intake contributed to the lower prevalence of obesity, diabetes, and dyslipidemia leading to a lower risk of ischemic heart disease. Albeit the moderate decline in IHD mortality, there has been an increasing trend for IHD incidence among urban middle-aged men (workers and residents) in Japan. This incidence trend is worth noting because of a potential future problem for public health and clinical practice. In such situations, the nutritional assessment is crucial to perform health counseling for nutritional improvements in the prevention of cardiovascular disease. The nutritional assessments are composed of 1) dietary assessment per se, i.e., by different methods such as dietary records, 24-hour recall, and food frequency questionnaire, and 2) assessment of biomarkers such as blood lipids, fatty acids, protein, amino acids, vitamins, and inflammation markers. Japan is unique among the developed countries where IHD mortality has been low and continued to decline. However, careful surveillance is needed to examine whether the complex changes in lifestyles, i.e., lowering sodium and rice intakes, recent lowering fish intake and smoking while increasing animal protein and saturated fat intakes, and physical inactivity may affect the future trend in cardiovascular disease.