A low salt diet known as the Dietary Approaches to Stop Hypertension (DASH) diet significantly lowers blood pressure in those with either high or normal blood pressure, according to a new report.

Scientists belonging to the DASH Sodium Collaborative Research Group studied 412 subjects who were randomly assigned to follow either a control diet that was typical of a normal US diet or the DASH diet, which emphasises fruits, vegetables and low fat dairy, and includes wholegrains, poultry, fish and nuts, but little red meat, sweets and saturated fats and cholesterol.

Sodium levels were varied periodically in both dietary groups. Thus, subjects ate foods with a high, intermediate and low level of salt for 30 days in random sequence. All of the participants had blood pressure higher than 120/80 mmHg and 41 per cent were hypertensive, with systolic blood pressures ranging from 140 to 159 mmHg.

The researchers found that reducing sodium intake from the high (150 mmol/ day) to the intermediate (100 mmol/day) level resulted in a decrease in mean systolic blood pressure of 2.1 mmHg among those on the control diet and a mean of 1.3 mmHg for those on the DASH diet. When salt was reduced to the lowest level (the target was 50 mmol/day), there was an additional mean reduction in systolic pressure of 4.6 mmHg among those receiving the control diet and a mean of 1.7 mmHg for those on the DASH diet.

Overall, when compared with the high sodium control diet, the low sodium DASH diet produced a mean reduction in systolic blood pressure of 7.1

mmHg among those who were not hypertensive and 11.5 mmHg among those who were hypertensive.

In this study, the effect of salt reduction from the recommended 100 mmol/ day to 50 mmol/day or the effect of the DASH diet, or a combination of the two, gave the same if not better results than antihypertensive drug therapy. More over, say the researchers, some patients already on drug therapy may be able to reduce their medication or even eliminate the need for it by making dietary adjustments (N Engl J Med, 2001; 344: 3-10, 53-4).