China Salt Trial

INTERVENTION: Group A:The participants will be provided with a supply of normal salt from market to be used in cooking and at the table. ;Group B:The participants will be provided with a supply of table salt containing equal amounts by weight of NaCl and KCl to be used in cooking and at the table.;Group C:The participants will be provided with education materials and with appropriate items to reduce their NaCl intake to 6g NaCl/day. ; CONDITION: hypertension PRIMARY OUTCOME: blood pressure, urine Na and K concentration, microalbuminuria, plasma renin activity, plasma aldost; INCLUSION CRITERIA: 1. Older than 18 year; 2. Families with an estimated salt intake> 200 mmol/d with 50% of the salt added in the cooking or at the table) This will be estimated through an interview with the participant; 3. Willingness to participant all aspects of the study; 4. Families have no plans to leave the region in the next two years; 5. Patients with hypertension treated or untreated are eligible to participate.