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11 May 2005 Increasing
Salt Intake Predisposes Hong Kong People
¡@¡@The most important modifiable environmental risk factors for hypertension include high salt intake, low potassium (vegetable and fruit) intake, obesity, alcohol intake, stress and low physical activity. The current WHO recommendations for adults to reduce their daily salt intake from 9-12 to less than or equal to 5-6g/day will have a major effect on blood pressure and cardiovascular disease. ¡@¡@Contrary to the people's knowledge on hypertension, surveys conducted by the Faculty of Medicine of The Chinese University of Hong Kong indicated that salt intake in Hong Kong people was on the rise and much higher than WHO recommendations. In healthy adults, the average salt intake increased from 8.0 g/day during 1989-1991 to 9.4 g/day during 1996-1998 and 9.9 g/day during 2000-2002. ¡@¡@Chinese are particularly susceptible to dietary salt-induced hypertension because they lack of an efficient mechanism to facilitate renal excretion of salt (sodium). Following an increase in dietary salt intake, the kidney normally synthesizes dopamine to inhibit sodium reabsorption and induce relaxation of blood vessels. This renal dopamine response is not seen in Chinese. In the early stage and before structural changes occur in blood vessels, salt-induced high blood pressure may still be reversible. ¡@¡@Reducing our current level of salt intake and optimising the other dietary and lifestyle factors have many advantages. The risk of hypertension is lower even in susceptible subjects (e.g. subjects with a family history of hypertension, the elderly, obese subjects and subjects with diabetes or renal disease). In patients with hypertension, reducing the salt intake may help control blood pressure and prevent complications (e.g. left ventricular hypertrophy, renal damage and cardiovascular disease). ¡@¡@The public should know the aetiological importance of salt intake and other factors in hypertension and the current recommendations and try to reduce their salt intake. Since 75-80% of intake derives from salt in processed foods, more attention should be paid to the sodium content in these food products. Patients with hypertension must have regular follow-ups and treatment. Even in apparently healthy adults, blood pressure should be monitored from time to time. |