By Howard LeWine, M.D.
Brigham and Women's Hospital

More results from the DASH (Dietary Approaches to Stop Hypertension) study have been published in the Annals of Internal Medicine. In this study, volunteers were provided with all of their meals and snacks for three one-month periods.

Some got a diet that emphasized vegetables, fruits, whole grains, fish, poultry and low-fat dairy products. Others received a "typical United States-type diet." The researchers varied the daily amount of salt from month to month.

Results from a previous DASH study (in which the amount of salt was kept constant) showed that the DASH diet all by itself can substantially lower blood pressure. These new results show that eating more salt tends to increase blood pressure, even among people eating a healthy diet. They also show that a low-salt DASH diet yields the largest reductions in blood pressure.

On average, those eating the very low-salt diet saw their blood-pressure readings go down about 4 points compared to those eating the high-salt diet (which contained the amount of salt most Americans consume daily).

Keep in mind, though, that this average does not mean the same thing will happen to your own blood pressure if you eat a low-salt DASH diet. If you have high blood pressure, it may drop by 10 points. Or it may not change at all. And for the rare individual, it may actually go up a little.

The good news from the new report is that eating less salt and following a DASH-type diet can help some people who are headed for hypertension control their blood pressure without needing to take drugs. For those already taking medication, a low-salt DASH diet might reduce the dosage they need, or even completely eliminate the need for drugs to maintain normal blood pressure.

Eating less salt has the most dramatic effects on blood pressure among African-Americans and people over age 45. But everyone with hypertension (blood pressure greater than 140/90) should try eating less salt. Even if it makes no difference in the readings, there may be other benefits. Many blood pressure drugs are more effective when combined with a low-salt diet.

For adults with normal blood pressure (less than 130/80), moderation will remain the message. While we don't know for sure whether eating less salt is healthier for these people, the DASH studies and others suggest that a healthy lower-salt diet may help prevent blood pressure from creeping upward. One thing is certain — it can't hurt.

Howard LeWine, M.D., is chief editor of Internet Publishing, Harvard Health Publications. He is a clinical instructor of medicine at Harvard Medical School and Brigham and Women's Hospital. Dr. LeWine has been a primary care internist and teacher of internal medicine since 1978.

Used with permission of the copyright owner. All rights reserved. This article is not intended to provide advice on personal medical matters or to substitute for consultation with a physician.