A pilot study of primary prevention of hypertension in China

In China stroke is now the leading cause of death. Because of the country's huge population, the medical approach to hypertension is proving expensive. It is also not very effective. Population-based primary prevention of hypertension would be cheaper and probably more effective. Based on the 1991 WHO/ISH statement on environmental factors and hypertension, and the distribution of those factors in Chinese society, we assume that: 1. In the genesis of essential hypertension in Chinese society, a high sodium — low potassium diet could be a fundamental environmental factor. Salt-induced hypertension could be a crucial contributor to the total occurrence of essential hypertension. 2. Reducing sodium intake, increasing potassium intake and reversing the existing high Na/K ratio to a desirable level (i.e. Na/K 1.0) should greatly assist in preventing essential hypertension in China. This thesis describes a preliminary trial undertaken in 1991-92 to test the feasibility of a proposed study in primary prevention of hypertension. Several hypotheses were tested. It was thought that a salt-free diet would modify and maintain users' urinary sodium and potassium excretion in the range of the Recommended Dietary Intakes (RDI) (adjusted for body weight) and keep the urinary Na/K ratio at 1.00. In areas prone to Iodine Deficiency Disorders (IDD) iodised rice was expected to take the place of iodised salt. It was expected that the new diet would cause no harmful physical and/or psychological problems and would be accepted and maintained voluntarily by the users after the trial. A total of 140 students aged 17-23 years joined the trial and 70 (about 20 females and 50 males) dropped out within the first month. The other 70 (26 females and 44 males) completed the trial. The trial procedures brought urinary sodium excretions down to the RDI for Australia (adjusted for body weight). Urinary Na/K ratios were brought down from 7.3 and maintained on about 1.3. Urinary iodine analyses showed the iodine supplement to be effective. With potassium supplementation urinary potassium excretions in the diet group were significantly higher than in the control group, however the overall average level did not meet the adjusted RDI. The trial also showed a gender difference in urinary electrolyte excretion opposite to that previously reported (more sodium in females) and unreported side effects including menstrual disorders and increased muscle cramping. The new diet was not positively accepted by the majority of the diet group and was difficult to maintain. In spite of dietary, managemental, cultural, and socio-economic difficulties, the author believes that the application of sodium restriction and potassium supplement to primary prevention of hypertension in Chinese society is a possible strategy. However people's habits and tastes would prove severe obstacles requiring the arts of persuasion