The DASH Diet – Does It Work?

Are you concerned about maintaining healthy blood pressure? The diet most often recommended by physicians is a good place to start. Let’s take a look at the DASH diet and relevant research findings that support it.

In the past, researchers tried to find clues about what in the diet affects blood pressure by testing various single nutrients, such as calcium and magnesium. These studies were done mostly with dietary supplements and their findings were not conclusive.

Then, scientists supported by the National Heart, Lung, and Blood Institute (NHLBI) conducted two key studies. The first was called “DASH,” for Dietary Approaches to Stop Hypertension. It tested nutrients as they occur together in food. Findings showed that blood pressures were reduced with an eating plan low in saturated fat, cholesterol, and total fat, and that emphasizes fruits, vegetables, and lowfat dairy foods.

The DASH diet also includes whole grain products, fish, poultry, and nuts. It’s reduced in red meat, sweets, and sugar-containing beverages. It’s rich in magnesium, potassium, and calcium, as well as protein and fiber.

blood pressure stats
Graphic based on 2014 survey by MillionHearts.hhg.gov – public domain

Two DASH studies and their results

The first DASH study involved 459 adults with systolic blood pressures of less than 160 mm Hg and diastolic pressures of 80–95 mm Hg. About 27 percent of the participants had hypertension.

DASH compared three eating plans:

  • A plan similar in nutrients to a typical American diet
  • A plan similar to what Americans consume, but higher in fruits and vegetables
  • The DASH diet

All three plans used about 3,000 milligrams of sodium daily. None of the plans were vegetarian or used specialty foods. Results were dramatic: Both the higher fruits and vegetables plan and the DASH diet reduced blood pressure. But the DASH diet had the greatest effect, especially for those with high blood pressure. Further, the blood pressure reductions came fast— within 2 weeks of starting the plan.

The second study was called “DASH-Sodium,” and it looked at the effect on blood pressure of a reduced dietary sodium intake as participants followed either the DASH diet or an eating plan typical of what many Americans consume.

DASH-Sodium involved 412 participants. Their systolic blood pressures were 120–159 mm Hg and their diastolic blood pressures were 80–95 mm Hg. Participants were randomly assigned to one of the two eating plans and then followed for a month at each of three sodium levels.

The three sodium levels were:

  • A higher intake of about 3,300 milligrams per day (the level consumed by many Americans)
  • An intermediate intake of about 2,400 milligrams per day
  • A lower intake of about 1,500 milligrams per day

Results showed that reducing dietary sodium lowered blood pressure for both eating plans. At each sodium level, blood pressure was lower on the DASH diet than on the other eating plan. The biggest blood pressure reductions were for the DASH diet at the sodium intake of 1,500 milligrams per day.

Those with hypertension saw the biggest reductions, but those without it also had large decreases. Those on the 1,500-milligram sodium intake, as well as those on the DASH diet, had fewer headaches.

Other than that and blood pressure levels, there were no significant effects caused by the two eating plans or different sodium levels.

DASH-Sodium shows the importance of lowering sodium intake —whatever your eating plan. But for a true winning combination, follow the DASH diet and lower your intake of salt.

Tips to help you reduce salt and sodium

  • Use reduced sodium or no-salt added products
  • Buy fresh, plain frozen, or canned with “no-salt-added” vegetables
  • Use fresh poultry, fish, and lean meat, rather than canned, smoked, or processed types
  • Choose ready-to-eat breakfast cereals that are lower in sodium
  • Limit cured foods (such as bacon and ham), foods packed in brine (such as pickles, pickled vegetables, olives, and sauerkraut), and condiments (such as MSG, mustard, horseradish, catsup, and barbecue sauce)
  • Limit even lower sodium versions of soy sauce and teriyaki sauce—treat these condiments as you do table salt
  • Be spicy instead of salty — flavor foods with herbs, spices, lemon, lime, vinegar, or salt-free seasoning blends
  • Start by cutting salt in half
  • Cook rice, pasta, and hot cereals without salt
  • Cut back on instant or flavored rice, pasta, and cereal mixes, which usually have added salt
  • Choose “convenience” foods that are lower in sodium
  • Cut back on frozen dinners, mixed dishes such as pizza, packaged mixes, canned soups or broths, and salad dressings—these often have a lot of sodium
  • Rinse canned foods, such as tuna, to remove some sodium

How to get started with DASH

It’s easy to adopt the DASH eating plan. Here are some ways to get started:

  • Change gradually … if you now eat one or two vegetables a day, add a serving at lunch and another at dinner
  • If you don’t eat fruit now or have only juice at breakfast, add a serving to your meals or have it as a snack
  • Gradually increase your use of fat free and lowfat dairy products to three servings a day
  • Choose lowfat (1 percent) or fat free (skim) dairy products to reduce your intake of saturated fat, total fat, cholesterol, and calories
  • Read food labels on margarines and salad dressings to choose those lowest in unsaturated fat
  • Treat meat as one part of the whole meal, instead of the focus
  • Limit meat to six ounces a day (2 servings)
  • If you now eat large portions of meat, cut them back gradually—by a half or a third at each meal
  • Include two or more vegetarian-style (meatless) meals each week
  • Increase servings of vegetables, rice, pasta, and dry beans in meals
  • Use fruits or other foods low in saturated fat, cholesterol, and calories as desserts and snacks
  • Try these snacks ideas: unsalted pretzels or nuts mixed with raisins; graham crackers; lowfat and fat free yogurt and frozen yogurt; popcorn with no salt or butter added; and raw vegetables

Here are a few more tips:

  • Choose whole grain foods to get added nutrients, such as minerals and fiber
  • If you have trouble digesting dairy products, try taking lactase enzyme pills or drops, or buy lactose-free milk or milk with lactase enzyme added to it
  • Use fresh, frozen, or no-salt-added canned vegetables

What’s wrong with the DASH diet?

DASH is often called “the best overall diet” for most people. There are a few drawbacks to the plan, though — although none are deal-stoppers and you can modify your own approach to DASH.

  • DASH doesn’t spell out any preference for organic foods — you’ll have to add that in yourself, if that’s your conviction
  • DASH doesn’t eliminate red meat altogether — something many people deem essential
  • DASH does not emphasize weight loss — if that’s your primary goal, you’ll probably need to modify DASH
  • There are no DASH meal plans or readymade dishes waiting for you — you’ll have to be DASH-aware and shop accordingly
  • Many people find the low-salt insistence of DASH leaves foods flavorless — you’ll need to get over it and improvise

All told, if you’re concerned about blood pressure, you should definitely take a look at DASH and incorporate the parts of it that make the most sense to you. As with all diets, it’s best to begin by talking with your physician.

(Thank you to the Kansas Department of Health and Environment for the research information listed here.)