Salt, Hypertension, and Cardiovascular Disease

Abstract

Excess dietary salt intake has been justified for almost 5,000 years by the adoption of salt as a unique food preservative, a feature no longer required in modern times thanks to the availability of more advanced food preservation technologies. Nowadays, a persistently high salt intake depends mainly on its addition to foods during industrial processing or home food preparation with the aim to improve their organoleptic characteristics or simply meet the perceived current taste preference. The risks of a high-salt diet emerged quite clearly in the second half of the twentieth century with the demonstration of the causal association between habitual high-salt intake and the incidence of various chronic degenerative diseases, primarily hypertension and its severe cardiovascular complications. Recent meta-analyses of randomized controlled trials have convincingly shown the efficacy of even a moderate reduction in salt intake in reducing blood pressure both in hypertensive patients, to a degree proportional to the severity of hypertension, and in normotensive subjects of all age groups. The relationship between habitual salt intake and the incidence of cardiovascular events, primarily stroke, in turn demonstrated by the meta-analysis of prospective studies, is felt to be mainly a consequence of the greater incidence of hypertension. There is increasing evidence, however, that the adverse effects of excess dietary salt intake are also linked to atherogenic mechanisms, oxidative stress, and endothelial dysfunction, which produce structural and functional alterations of the arterial wall with subsequent organ damage. Taken together, these findings provide the bases for the recommendations made by the main scientific societies and by the World Health Organization in favor of the implementation of national strategies to reduce dietary salt intake at the population level through educational campaigns and negotiations with the food industry for appropriate food reformulation and progressive reduction of hidden salt in the food available to purchase.