To the Editor: There is an established link between salt intake and blood pressure. The public health impact of a 1–3 mmHg reduction in blood pressure by lowering salt intake could be substantial. An American study found that a projected reduction in diastolic blood pressure of 2 mmHg would result in a 17% decrease in the prevalence of hypertension, a 6% reduction in the risk of coronary artery disease events, and a 15% reduction in risk of stroke and transient ischaemic attacks.1 In Finland, a one-third decrease in average salt intake achieved over 30 years was accompanied by a fall of more than 10 mmHg in the population averages of systolic and diastolic blood pressure.2 However, in the absence of active measures to reduce salt in the food supply, public health messages to reduce salt intake have largely been unsuccessful.

The National Health and Medical Research Council (NHMRC) has recently revised its recommendations and now states that an adequate sodium intake for adults is 460–920 mg/day (20–40 mmol/day), with a suggested dietary target for chronic disease prevention of 1600 mg/day (70 mmol/day).3

The most recent Australian sodium intake data are from the 1995 Hobart Salt Study, in which the then national target of 6 g/day was achieved by only 6% of men and 36% of women, with an average salt intake of 7–10 g/day.4 Volunteers in weight-loss studies at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) Human Nutrition unit over the past 5 years continue to have a high salt intake of 8–11 g/day (urinary sodium/24 h: men [n = 85], 181 ± 95 mmol; women [n = 189], 136 ± 61 mmol; reference range, 40–100 mmol).5 Recent data from another Australian study report similar urinary sodium concentrations.6 The average salt intake of Australian adults appears to be 7–12 g/day, which is little changed from 10 years ago.

Achieving a low salt intake in the present food supply is difficult, as more than 80% of intake is from salt added to food during processing. As well as the more obvious foods in which salt is a preservative, staple foods such as bread also contain salt. The variety of foods has increased considerably, and many of the numerous processed foods now available contain very high salt levels. Processed and convenience foods frequently have salt added that the consumer cannot avoid. It is clear that large changes to the food supply are needed to reduce salt intake. We believe that salt reduction in the food supply should be the first line of attack to reduce the risk of cardiovascular disease in the population.