Prevention of Hypertension and Cardiovascular Diseases

Abstract

A ppropriate lifestyle modifications are a fundamental step to prevent hypertension, which is the strongest risk factor for cardiovascular disease (CVD). 1,2 However, the slope of the association between blood pressure (BP) and stroke is steeper among Asians than Westerners. 3,4 This result is partly explained by the higher proportion of strokes that are hemor-rhagic in Asian compared with Western populations and the steeper association of BP with hemorrhagic stroke as compared with ischemic stroke. 5 The population-attributable fractions of hypertension for ischemic stroke in men and women have been reported as 40% and 36% in China, 34% and 35% in South Korea, 37% and 39% in Japan (East Asian), 15% and 44% in Australia, and 18% and 43% in New Zealand (Western), respectively. 6 These differences between Westerners and East Asians depend on both genetic (racial) and lifestyle factors. A schema of the progression from lifestyle behaviors to the onset of stroke and coronary heart disease (CHD) is shown in the Figure. Lifestyle (modifiable) and genetic (unmodifiable) factors are key cardiovascular risk factors, especially higher BP (the primary stage of CVD prevention). Furthermore, car-diovascular risk factors, especially hypertension, are key factors for the prevention of CVD (the secondary stage of CVD prevention). To prevent CVD, it is important to improve lifestyle and reduce cardiovascular risk factors in the early stage. The health behaviors appearing in recent guidelines for the management of hypertension are also important for the primary prevention of stroke. The guidelines put out by the United States, 7 Europe, 8 China, 9 and Japan 10 for lifestyle modifications for prevention of hypertension are similar, namely: (1) salt restriction, (2) high consumption of vegetables and fruits, (3) increased intake of fish and reduced content of saturated/total fat, (4) appropriate weight control, (5) regular physical exercise, (6) moderate alcohol consumption, and (7) quitting smoking. These factors are also considered as important stroke-prevention guidelines. 11,12 In this review, I compare finding from studies on lifestyle status in Westerners and East Asians in relation to these basic hypertension guidelines (Table). Salt Restriction Many epidemiological studies have shown that reduced salt intake is directly related to decreased BP. 13-15 The Dietary Approaches to Stop Hypertension (DASH) diet, which was a randomized trial comparing the effects on BP of 3 total salt intake levels (8.3, 6.2, and 3.8 g/d for high, intermediate, and low salt intakes), showed significantly lower systolic (SBP, −5.9, −5.0, and −2.2 mm Hg) and diastolic BPs (DBP, −2.9, −2.5, and −1.0 mm Hg) at each salt level, respectively. 14 The DASH diet and salt reduction independently lowered SBP and DBP. In a Chinese study that included a 7-day low-salt intervention (51.3 mmol/d), a 7-day high-salt intervention (307.8 mmol/d), and a 7-day high-salt plus potassium supplemen-tation (60 mmol/d), the correlation coefficients of the SBP responses to low-sodium and high-sodium intervention were −0.47 and that to high-sodium intervention and potassium supplementation was −0.52. 16 These correlation coefficients were greater than those reported by the DASH-Sodium trial. 17 The Intersalt Study 13 and the INTERMAP (International Study of Macro-/Micronutrients and Blood Pressure) Study 18