Intersalt study

The INTERSALT Study was a 1988 international observational study which investigated the link between dietary salt, as measured by urinary excretion, and blood pressure. The study was based on a sample of 10,079 men and women aged 20–59 sampled from 52 populations around the world. The authors of the study provided a widespread international investigation of the correlation between dietary salt intake and blood pressure in a systematic and standardized way with regards for relevant confounding variables, beyond just age and sex.^[1]

Results

The study found a significant direct relationship between dietary salt intake, the urinary sodium:potassium ratio and systolic blood pressure, and between salt intake and the slope of blood pressure with age – both for all 52 populations, and for 48 populations excluding four low-sodium populations (Yanomamo and Xingu Indians of Brazil, Papua New Guinea and rural Kenya).^[1]

Reception

The results were disputed by the Salt Institute (the salt producers' trade organisation, since disbanded), who demanded that the results be handed over for re-analysis.^[2] A re-analysis was published in 1996 and the results were the same.^[3] The results have since been confirmed by the TOHP I and TOHP II studies,^[4] trials of salt reduction and blood pressure in chimpanzees,^[5][6] meta-analyses of the human clinical trial data^[7] and the SSaSS trial of salt substitute and cardiovascular disease.^[8]