Dear Ms Brown,

You misunderstood several important points about the DASH diet. Most important: DASH is not sodium-reduced.

As president of the Salt Institute, representing the salt industry, I have monitored the literature carefully. You have made two fundamental errors in your article: DASH does not reduce sodium, and dairy products are integral to the benefits of the DASH diet.

DASH was published in 1997 and controlled, and held constant, the amount of sodium. In this 30-day feeding study, hypertensive subjects reduced their systolic blood pressure (SBP) by 11.4 mmHg. DASH is high in fruits, vegetables and dairy products. Your discussion omits dairy products and they are as important as fruits and vegetables combined.

The (US) government sponsored the trial and was unhappy with the results since they did not show any benefit of reducing sodium, so they undertook a second study that combined two interventions - the DASH diet with a low-sodium diet that reduced sodium by two-thirds. Put aside whether this is feasible in the general population (DASH was for only 30 days, used highly motivated volunteers who received intensive dietary counselling and whose entire food intake was provided free for that month). The results: those who consumed both the DASH diet and took in 1,500 mg/day Na reduced their SBP by 11.5 mmHg.

Thus, 11.4 mmHg is the "DASH effect" on BP and 0.1 mmHg is the "sodium effect." You decide if 'sodium monster' conveys the results on the research properly.

The Cochrane Collaboration and the US Preventive Services Task Force have reviewed the evidence and agree with the editor-in-chief of the American Journal of Hypertension that there is no evidence supporting any health benefit for reducing dietary sodium.

For more information, your readers may wish to visit www.salthealth.org.

Dick Hanneman

Salt Institute

Response

Dear Mr Hanneman,

Thank you for your letter and for reading this column. I too would like to make some corrections.

I am aware of the DASH studies and have written about them on numerous occasions. I made reference to the DASH diet, that is, recommended eating guidelines coming out of the study. I did not note all of its components with particular reference but spoke about them in the general article, as these guidelines are part of the general recommendations given for health management.

The DASH diet encourages an eating plan low in saturated fat, cholesterol and total fat and emphasises vegetables, fruits and fat-free or low-fat dairy products. The plan also includes whole-grain products, fish, poultry and nuts. It recommends reduced intake of lean red meat, sweets and sugar-added beverages. The second study of the DASH looks at the effect of reduced sodium on blood pressure and showed significant benefits, especially for persons with existing high blood pressure, older individuals and African Americans.

The DASH diet, therefore, recommends a goal for sodium of 2,300mg each day and indicates that 1,500mg per day is better for persons with existing high blood pressure, especially for those who are older and of African-American heritage.

Reduce sodium intake

I have visited the Salt Institute's website and note your concerns, but as a dietitian, I recommend a healthy lifestyle and overall health and well-being. Sodium can be safely reduced in our diets without compromising flavour, and this should be done in conjunction with consuming whole foods which are beneficial to our total well-being.

The DASH study is not the only study which shows the effect of high sodium intake on blood pressure control. Two recent studies reviewed in August 18 issue of the AARPBULLETINtoday (I have not yet read the studies), reported evidence from researchers out of St George's University, London, that even modest reduction in sodium chloride for six weeks can lower high blood pressure and may have beneficial effects on the kidneys and bones. In a second study in Australia, it was found that high-salt diets may reduce the effectiveness of blood pressure medication. My professional recommendation is that consumers should eat less sodium. This can be achieved by consuming less processed foods as sodium is a major ingredient.

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