Diet, central obesity and prevalence of hypertension in the urban population of South India

Central obesity is a strong predictor of higher prevalence of diabetes, hypertension and coronary artery disease among Indian immigrants to Britain. To test this hypothesis in Indians, 1569 adults, between 25 and 64 years of age, from 750 randomly selected households (representative of 0.52 million population of Trivandrum city, Kerala) were selected for this study. The response rate was roughly 95% and the sample consisted of 1497 individuals (737 males and 760 females). The survey methods included dietary diaries for 7-day food intake record, blood pressure measurements using a mercury sphygmo-manometer and anthropometric measurements. The prevalence rates of hypertension between 25 and 64 years was 189/1000 (95% confidence limits 85–360) and between 45 and 64 years was 335/1000 (95% confidence limits 210–460) which is higher than in Western populations. The prevalence was higher in males than females in the younger age groups and comparable in both sexes in the upper age groups. The prevalence of central obesity was significantly higher among male (77.2 vs. 48.9%) and female (84.0 vs. 51.4%) hypertensives compared to non-hypertensive subjects; however, mean body weight, body mass index and waist-hip ratio (WHR) were lower among Indian men compared to a British comparison group. Thus, comparison of Indian men with Britons showed that obesity, salt and alcohol intake, sedentariness, smoking and dietary fat intake do not explain the cause of higher prevalence of hypertension among South Indian men from Kerala. However, further analysis of data in relation to WHR showed that male subjects with higher quintiles of WHR (>0.85 and females >0.81) had significantly higher prevalence of hypertension and diabetes compared to the lowest quintile of WHR. Energy expenditure during daily physical activity for each upper quintile of WHR was lower, and dietary fat energy intake was the higher compared to the lowest quintile of WHR. These findings suggested that Indians could benefit by decreasing total fat intake to 21% kcal/day and by increasing physical activity with the aim of decreasing central obesity, to prevent hypertension in the community.