There are no randomised controlled trials of effects of varying sodium intake on cardiovascular outcome other than on blood pressure levels per se . In this issue of the Journal Beard et al. have attempted to measure salt intake in an Australian population sample in the light of our national target for the year 2000. Interestingly, among both men and women, and among both those who did and those who did not comply with the sodium intake target, most stated that they never or rarely added salt to food. This apparent anomaly may raise doubts about the reliability of the participants' reports, but is probably more readily explained by the poor reliability of a single 24-hour urine specimen for estimating usual sodium intake, and the high proportion of dietary salt hidden in food. Given the proportion of participants in the study by Beard et al. who claim not to add salt to food or in cooking, the figure may be higher in Australia.
Bread is a major source of dietary salt, along with canned foods and preserves.
Take-away foods are more likely to be salted, and the growing habit of eating out leaves the consumer with less control over salt intake. Beard et al. point out that there has been relatively little publicity about the national dietary target for salt and that, although some food manufacturers have taken initiatives to reduce salt use, shoppers receive relatively little advice or encouragement. The picture is perhaps not quite as bleak as it seems. The National Heart Foundation and State health departments have long been publicising the benefits of reducing salt intake as part of a more general healthy diet that includes eating more fresh fruit and vegetables and reducing saturated fat intake. These measures may have much greater value in cardiovascular health if adopted in combination with other lifestyle changes.