Dietary Salt and Blood Pressure: Verdict is Clear, so why Any Debate?

Repeated reviews of the evidence to produce recommendations for dietary salt intake have been conducted by independent committees of national and international scientific and governmental organizations. These recommendations support reducing dietary salt to less than 6 gm/day and many to less than 5 gm/day. Nevertheless, there is controversy about recommendations to reduce dietary salt. This commentary discusses low quality research studies and commercial interests as sources of the controversy. Especially, research that assesses usual salt intake in individuals based on a single spontaneously voided (spot) urine sample is discussed as a weak research method prone to erroneous findings. Further, some investigators have altered scientific formula to make their data using spot urine samples appear more robust and made misleading and false statements about evidence relating to dietary salt. Counterintuitive findings based on studies that have used spot urine samples is frequently disregarded in expert committee review given the low quality evidence is incompatible with higher quality evidence which shows direct linear relationships between dietary salt, hypertension and cardiovascular disease in the general population.