Low prevalence of metabolic syndrome and its components in rural Japan

Tsunan, Niigata is a non-westernized rural Japanese town, known for heavy snowfalls and as a rice-producing area, whose inhabitants have a long life expectancy. We investigated the prevalence of obesity, metabolic syndrome (MetS) and its components in Tsunan. A total of 1,155 men and women, 40-69 years of age were recruited from participants in the 2005 public-health program in Tsunan. Obesity was defined as body-mass index (BMI) >or= 25 kg/m(2). MetS was defined as BMI >or= 25 kg/m(2) as well as at least two of the following three items: (1) high glycosylated hemoglobin (HbA1c >or= 5.5%); (2) high blood pressure (HBP: systolic blood pressure >or= 130 mmHg or diastolic blood pressure >or= 85 mmHg), and (3) low high-density lipoprotein cholesterol (HDL-C < 40 mg/dL). If an individual was diagnosed with diabetes, hypertension, or dyslipidemia, each item was recorded as a positive finding. The prevalence of MetS and its components among Tsunan inhabitants were compared to the results of the 2005 Japanese nationwide survey. The prevalence of MetS was 4.6% in males and 4.2% in females. The prevalence of obesity, high HbA1c, HBP, and low HDL-C were 22.1/22.2%, 13.4/16.4%, 46.6/40.0%, and 9.2/3.9% in males/females, respectively. All values were significantly lower than the national results, except for the rate of female obesity. The lower prevalence of MetS and its components in Tsunan may be due to the consumption of traditional Japanese food, which is still commonly eaten there, and the higher levels of regular physical activity of farmers.