A community-based intervention study on the feasibility and effects of the reduction of salt intake in North Karelia, Finland.

A community-based programme to reduce salt consumption to lower general blood pressure levels has been started in North Karelia, a county eastern Finland with high hypertension and CVD rates. The programme is based on the previous activity in the community to control CVD risk factors (the North Karelia Project). Previously, however, salt reduction was not included among the objectives. The aim of the study is to evaluate the feasibility and effects of this new community programme to reduce salt intake. The study period is from spring 1979 to spring 1982. At the outset and at the end cross-sectional random population samples, ages 14 to 65, are examined both in North Karelia and a matched reference community. The surveys include among other measurements 24-hour urine collection (for Na, K and creatinine excretion) and blood pressure. The effect evaluation is concerned whether the programme reduced the general salt intake and whether this was associated with reduction in blood pressure levels among the population. Principles and methods of intervention are presented. Preliminary results from the baseline survey confirmed the high salt intake of the population: the mean 24-hour urinary Na excretion was 215-218 mmol among men and 171-173 mmol among women. The respective K excretion values were 89-91 mmol and 72-72 mmol, and Na/K ratios 2.5-2.6 and 2.4-2.5.