The Salt Institute (SI) has long argued that dietary salt has little impact on blood pressure (BP) in normotensive people and only raises BP modestly in those with hypertension (HTN) who are ?salt sensitive?. The results from the DASH-Sodium trial discredit both claims. This study, unlike many in the past, which found little or no impact of dietary salt and BP, accurately controlled and monitored sodium intake. According to Dr. Eva Obarzanek, a?nutritionist and Project Officer for DASH-Sodium, the results showed that reducing dietary sodium by less than 1 tsp daily (about 1800 mg of sodium) reduced BP slightly more than the original DASH diet which was high in fruits, vegetables and low-fat dairy products. However, the DASH diet with a low-sodium intake (about 1500 mg/d) proved to be by far the most effective strategy for lowering BP in people with HTN and those with normal BP.
In a press release, the SI claims, ?we know from the Trials of Hypertension part II study that there is an immediate BP lowering result of sodium restriction which disappears over time.? Really? Then why is it that in every human population ever studied in which very little or no salt is added to the diet BP does not increase with age as it does in populations that do add salt to their diet. The Trials of Hypertension part II, like so many before it, found it difficult to keep people on a reduced salt diet because so much salt is added to processed foods and to foods consumed away from home. This makes sticking to a low-salt diet difficult without intensive dietary counseling. The DASH-Sodium study overcame this problem by providing all the foods consumed by their subjects during the study.
The drop in systolic BP was 11.5 mmHg in just 4 weeks on the DASH low-sodium diet. By contrast, the average rise in systolic BP during adulthood in all societies that consume as much salt as Americans is about 50 mmHg. If one actually follows a low-salt diet (<1500 mg sodium/d) DASH-style diet for many years, BP will usually drop very slowly (after an initial big drop in the first 2-3 weeks) over the next 5-7 years. Even greater drops in BP will occur if people exercise, lose excess body weight and moderate their alcohol intake as well as eat a low-fat, low-salt diet with plenty of fruits, vegetables, whole grains and moderate amounts of nonfat dairy products and fatty cold water fish e.g. salmon, mackerel or herring.
By Dr.?James Kenney, PhD, FACN
Stephanie Ronco has been editing for Food and Health Communications since 2011. She graduated from Colorado College magna cum laude with distinction in Comparative Literature. She was elected a member of Phi Beta Kappa in 2008.