From the "a news release" link: "Using health data gathered from 11,255 adults over a 30-year period, researchers analyzed links between serum sodium levels –

From the "a news release" link: "Using health data gathered from 11,255 adults over a 30-year period, researchers analyzed links between serum sodium levels – which go up when fluid intake goes down – and various indicators of health. They found that adults with serum sodium levels at the higher end of a normal range were more likely to develop chronic conditions and show signs of advanced biological aging than those with serum sodium levels in the medium ranges. Adults with higher levels were also more likely to die at a younger age. " Um. Clearly that's correlation.