Cardiovascular disease is a leading cause of death and disability worldwide, and blood pressure is a leading determinant of this risk. To date, strategies for blood pressure lowering have focused on drug treatment but dietary interventions such as reducing sodium intake and increasing potassium intake may also be effective. Such interventions may be particularly suitable for low- and middle-income countries in which significant dietary changes may be more easily achieved. This study will test the effect of a salt substitute on blood pressure, among individuals at high-risk from cardiovascular disease in Northern China.