The relationship between sodium (Na) intake and human health indicators has been investigated in observational studies and randomized controlled trials (RCT). The most extensive body of information details the relationship between Na and blood pressure (BP). High BP was identified as the leading risk factor, among 67 studied, for worldwide mortality and disability adjusted life years. It is also one of the best surrogate markers for cardiovascular disease (CVD), especially stroke. Consistent with prior reports, three recent meta-analyses of RCT identified significant declines in BP following a reduction in Na intake. The decrements in BP were greater in those with higher starting levels of BP, more successful intervention, older age, and African-American ethnicity. In the two meta-analyses with greatest relevance for clinical practice and public health, Na reduction was associated with a small but expected physiological increase in elements of the renin-angiotensin-aldosterone system, little or no effect on total cholesterol or catecholamine levels, and changes in urinary protein consistent with a beneficial effect on renal function.