It turns out that the accepted wisdom on dietary salt, that too much causes dangerous increases in blood pressure, might be a little oversimplified.
The body strives to maintain a constant level of salt in the blood; when there is too much, the body draws water in from surrounding tissues to keep the correct concentration. This process is called homeostasis and is important for physiological function.
However, increases in blood volume cause pressure in blood vessels to rise, which can then lead to a stroke, heart attacks, and other problems.
Over the past few decades our view on dietary salt has become a little more nuanced: research suggests there are two different type of people – about half of all adults are ‘salt sensitive’, meaning consuming salt will increase their blood pressure, while the rest are ‘salt tolerant’, meaning they can consume salt without an increase in blood pressure.
Although these categories have been around for years, people were unsure as to why this is the case. Interestingly, there is a greater death rate for adults who are ‘salt sensitive’ irrespective of their blood pressure, so we know it’s important.