A study by Dr Michael Alderman and colleagues, from the Albert Einstein College of Medicine in New York, USA, found that after adjustment for age and sex, the mortality rate from any cause was highest among people who reported the lowest salt (sodium) intake (23·18 per 1000 person-years). The mortality rate was lowest (19·01 per 1000 person-years) in the group with the highest sodium intake. The results of their study appears in this week’s The Lancet.

The data on which the study was based were collected in 1971-75 in the first National Health and Nutrition Examination Survey (NHANES I). In this study, 11 346 US adults (aged 25-75) were medically examined and gave details of their food intake, by recalling all they had eaten during a 24-hour period. In 1992, the researchers searched the US national death index and traced and interviewed surviving participants. They then calculated the death rates in four groups (quartiles) defined by the salt intake or the total calorie intake reported at the original survey. 3293 people had died, 1970 from cardiovascular causes.

The findings were similar for death from any cause and for death from cardiovascular disease specifically. The rates decreased from the highest to the lowest quartile of sodium or calorie intake. For the ratio of sodium to calorie intake (ie, salt as a fraction of everything eaten), however, the death rate increased slightly from the lowest to the highest quartile (from 20·27 to 21·71 per 1000 person-years). These data are valuable, say the investigators, because they relate sodium intake to the eventual mortality rather than to an intermediate variable such as blood pressure. They emphasize that these data do not justify any particular dietary recommendation. The findings "do not support current recommendations for routine reduction of sodium consumption, nor do they justify advice to increase salt intake or to decrease its concentration in the diet".