Do low-salt diets improve health outcomes? The evidence
There have been relatively few studies of the fundamental question of whether reducing an individual's -- or a population's -- salt intake will improve their health outcomes. Usually only one risk factor is considered: blood pressure. Other impacts confound blood pressure, itself a rather herterogeneous response. None of the outcomes studies is a controlled trial. Thus, policies embracing universal salt (or sodium) reduction have a weak foundation in the medical literature.
Here are the health outcomes studies reported publicly with links to the original sources where available:
Cutler, J.R., Presented May 30, 1997, at American Society of Hypertension annual meeting, San Francisco, CA. (unpublished).
Tunsall-Pedoe. “Comparison by prediction of 27 factors of coronary heart disease and health in men and women of the Scottish heart health study cohort study. British Medical Journal, 1997; 315:722-729. See Table 6, age-adjusted hazard ratios.
Valkonen, V-P. “Sodium and potassium excretion and the risk of acute myocardial infarction” Presented October 15, 1998 to the American Heart Association Scientific Sessions, Dallas, TX (unpublished).
Cohen, J.D. presentation to NHLBI Workshop on Sodium and Blood Pressure, January 28, 1999, Bethesda, MD
Grobbee, D.E. et al. "Sodium and potasium intake and risk of cardiovascular events and all-cause mortality: the Rotterdam Study" presented to the 13th European Meeting on Hypertension in Milan, Italy, June 13-17, 2003 (published abstract)
Cook, N.R. et al "Long term effects of dietary salt reduction on cardiovascular disease outcomes: observational follow-up of the trials of hypertension prevention (TOHP)." British Medical Journal, doi:10.1126/bmj.39147.604896.55 (published 20 April 2007)
Cohen, H.W. et al "Sodium intake and mortality follow-up in the Third National Health and Nutrition Examination Survey (NHANES III). Journal of General Internal Medicine (6) Online First (May 2008) -- likely to be published in the July edition
Stolarz-Skrzypek, et al "Fatal and Nonfatal Outcomes, Incidence of Hypertension, and Blood Pressure Changes in Relation to Urinary Sodium Excretion." The Journal of the American Medical Association (JAMA). 2011.