Salt and blood pressure revisited.

Modern attempts to link intake of salt with population blood pressure (BP) show striking similarity to early 19th century attitudes which attributed human disease and premature death to inappropriate diet. Under these circumstances there is a danger that conviction of the truth of a hypothesis may lead to selection of evidence. A pooled meta-analysis of rigorously conducted studies of the effect of salt restriction on BP has been carried out. This indicates small but real effects in hypertensive patients although the degree of heterogeneity cannot be assessed. The effect in normotensive subjects is minimal and throws doubt on the value of general reduction in salt intake in lowering population BP.