In 1997, an eating plan named DASH: Dietary Approaches to Stop Hypertension was published as a scientifically proven dietary means of preventing and/or controlling hypertension. The eating pattern emphasizes fruits, vegetables, low-fat dairy foods, whole grains, poultry, fish, and nuts consumed in a total daily consumption of approximately 2000 calories. In the initial study, people with elevated blood pressures who followed the DASH diet lowered their blood pressures an average of 11.4/5.5 mm Hg; these results are as good as many blood pressure medications can achieve. However, in those earlier dietary studies, the salt content in all three analyzed eating patterns was kept constant at about 3 grams of sodium per day. As a consequence, the question of whether sodium restriction could further control/lower blood pressure was not answered at that time.
Over the last two decades, there has been considerable debate about the value of sodium restriction and blood pressure effects. Several studies in the 1980s concluded that salt restriction had no effect on blood pressure at all. However, multiple studies since then have found that reduced salt intake can decrease average blood pressures, decrease age-specific stroke mortality, and decrease mortality from heart disease. To further assess the role of sodium in blood pressure control, a new DASH trial, the DASH-Sodium trial, has recently been completed. Its results are impressive. . . certainly worth their salt.
Volunteers were stratified into three groups: one group consumed an average of 3,300 mg of sodium per day (about the average American consumption); one group consumed 2,400 mg per day, and the third group consumed 1,500 mg of sodium per day. Results were clear; the lower the sodium in the diet, the lower the blood pressure–whether volunteers followed the typical American diet or the DASH diet. The biggest blood pressure benefit occurred in the hypertensive people, but even people with normal blood pressures dropped their readings as well. The biggest drops in blood pressure were seen in the lowest sodium-consumption group who followed the DASH diet–an average drop of 11 mm Hg in hypertensive people and 7 mm Hg in volunteers with normal blood pressure. These results were consistent in men and women, African Americans and caucasians. We physicians have known for a while that there are a group of ‘salt sensitive’ individuals who have a genetic predisposition for blood pressure elevation with salt consumption. But, it’s new news that reducing dietary sodium can actually benefit people with normal blood pressures by decreasing their risk of ever developing hypertension. Additionally, the DASH-Sodium trial indicates that a salt consumption below the current recommendations could help many Americans prevent the blood pressure rises that seem to occur ‘naturally’ as we age.
So, based on this new information, who should limit their salt intake? The answer is: EVERYBODY! Unfortunately, this is not as easy as it sounds. 2,400mg of sodium is equivalent to approximately one teaspoon of salt. Though most of us do not intentionally add this much salt to daily meals, we get much of our dietary sodium from prepared foods. Processed foods, soups, canned vegetables, peanut butter, and most snack foods are very high in sodium content as are the fast-food meals that so many of us grab as we race between obligations. Additionally, salt helps to enhance the flavors of many foods, so cutting back on usage can diminish the sensory pleasure of a meal. Nevertheless, with an average consumption of 3,300mg of sodium per day (and some folks consuming up to 6,000mg per day), most of us are well above the recommended 1,800 mg/day advocated by the National Research Council of the National Academy of Sciences or the 1,500mg/day found to be the ideal consumption in the DASH trial.
In conclusion, if you have high blood pressure and/or are significantly overweight, you will receive the greatest health benefits from restricting salt in your diet. But ALL of us can benefit from sodium restriction by decreasing our lifetime risk of ever developing blood pressure problems. The more you restrict (aiming for a daily consumption in the 1,500 to 1,800mg/day range) the greater your benefit will be. Try to eat fresh fruits and vegetables whenever possible and make a conscientious effort to limit consumption of processed foods, highly salted snacks and fast foods. Experiment with herbs and spices as a substitute seasoning to add flavor and zest to meals. By making these long term dietary changes, you might just improve your chances of making it to that stage in life when you’ll be known as a salty ole sage.
You can obtain more information about the DASH diet at http://dash.bwh.harvard.edu/dashdiet.html
Stephen L. Hines, M.D.