Description
The National Heart, Lung, and Blood Institute (NHLBI) convened a working group of multidisciplinary researchers on May 29, 2014, in Bethesda, MD, to share current knowledge regarding the effects of dietary salt on the human body and to explore and identify scientific gaps and challenges.
This working group is responsive to NHLBI Strategic Plan Goals 1, 2, and 3 (2007).
Background:
Humans have had a long and complicated relationship with salt. While highly valued in many societies, dietary salt has long been associated with high blood pressure, or hypertension, and, more recently, other diseases. One study found that about half of the subjects with high blood pressure had salt-sensitive hypertension, a condition more prevalent among African Americans, older persons, and individuals with renal insufficiency or diabetes. In general, for those with salt-sensitive hypertension, excess sodium intake is associated with high blood pressure, while a low-salt diet decreases blood pressure. In spite of this well-known association, the basic biological mechanisms underlying the effects of salt on blood pressure regulation are still not well understood. In addition, although individuals with high blood pressure are at increased risk for coronary artery disease, heart failure, stroke, and renal disease, it is unclear whether a high dietary salt intake directly leads to cardiovascular diseases—i.e., in the absence of hypertension.
Our understanding of the effect of salt on health grew even more complex with a recent finding. Researchers reported a new connection between salt and autoimmunity: a high-salt diet was shown to accelerate autoimmune activity in a mouse model of multiple sclerosis. Interestingly, recent research has also revealed a connection between hypertension and the immune system: basic science experiments demonstrated that the immune system contributes to hypertension, and clinical observations indicate an increased incidence of hypertension in patients with certain autoimmune conditions, such as psoriasis. As is the case with hypertension, salt, and cardiovascular disease, scientists have not yet worked out the causal relationships between salt, immunity, and hypertension (e.g., how salt may mediate interactions between the immune system, vasculature, brain, and kidney to control blood pressure).