We have been told for years to limit our salt intake for the sake of our health.
Now, new research on rats, partly done at the University of Otago, has discovered how salt affects a part of the brain that controls blood pressure.
Researchers said more research was needed on whether the same thing happened in humans, and how it might be reversed.
The link between salt and hypertension is well known, but the research showed a brain mechanism by which salt affects blood pressure by altering neurons that release the hormone vasopressin.
Excessive salt when ingested over a long period interfered with the natural safety mechanism that prevented high blood pressure.