Nutrition Action Healthletter
October 1997 — U.S. Edition


Don't have high blood pressure?

Don't assume you never will.

One out of four American adults does. Among people 60 or over, it's one out of two (see "Older and Higher").

But that doesn't mean everyone else is in the clear.

Say your doctor says that your blood pressure is "high normal," or even "normal." Sounds good, huh?

Not so good.

Even so-called normal blood pressure raises the risk of heart disease and stroke. What you want is "optimal" blood pressure (see "What's Your Risk?"). Less than half of all Americans have it ... and most of them are young.

How can you keep your blood pressure from creeping up from optimal to normal to high?

For years, experts have recommended four proven strategies. The Big Four: cut back on salt; lose excess weight; exercise; and, if you drink, limit alcoholic beverages to two drinks a day.

Now we can make it the Big Five. A landmark study called DASH -- Dietary Approaches to Stop Hypertension -- shows that eating the right foods also works. It can lower blood pressure as much as taking a drug.

Better yet: It's the same diet that may help cut your risk of cancer, heart disease, osteoporosis, and diabetes.

Designing DASH

For years, researchers were stumped.

"In the 1970s, we found that blood pressures were lower in vegetarians, who eat little or no fat and cholesterol and lots of fruits, vegetables, and grains rich in potassium, magnesium, and fiber," says Frank Sacks, a researcher at Harvard Medical School who helped create the DASH study.

Other studies showed that people who ate more protein also had lower blood pressure. And some scientists argued that calcium played a role as well.

But when researchers gave people calcium or magnesium supplements, blood pressures barely budged.

"In the Trials of Hypertension Prevention, the only thing that lowered blood pressure was cutting back on salt and reducing overweight," says Jeremiah Stamler, professor emeritus at Northwestern University Medical School in Chicago, who also helped design DASH.

"The scientific literature was confusing," says Lawrence J. Appel, a DASH researcher at Johns Hopkins University in Baltimore. So they constructed a diet to provide all of the promising nutrients.

"We decided to test the whole diet, not supplements," says Sacks.

Researchers enrolled 459 adults at four centers around the country. Less than a third already had hypertension. The rest had normal or high-normal blood pressure -- that is, diastolic pressure between 80 and 89. ("Diastolic" is the lower of the two blood pressure numbers.)

For eight weeks, people were randomly assigned to one of three diets:

"We kept the salt constant in all three diets at 3,000 mg a day," says Appel. (That's slightly less than the average American's 3,600 to 4,000 mg a day, but more than the 2,400 mg health experts recommend.) Ditto for other things known to influence blood pressure: Calories were the same for all three diets (so no one would gain or lose weight) and alcohol was limited to a drink or two a week.

The researchers didn't have to wait long.

The Winner

"Blood pressure fell within days," says Appel. The fruit and vegetable diet lowered pressure significantly. But the combination diet won hands down. It lowered average pressures by:

"That's about what you'd get in people given a drug," says Appel.

Why such success when supplements of calcium, magnesium, and other individual nutrients flopped in earlier studies?

"Maybe you need to eat the nutrients together because the effect of each one is small," says Eva Obarzanek, a DASH co-author at the National Heart, Lung and Blood Institute in Bethesda, Maryland. "Or maybe the foods improve the absorption of the nutrients."

It's also possible that something else in fruits, vegetables, and low-fat dairy products lowers blood pressure. The DASH can't say. Nor can it say which nutrients made the difference.

But it said enough.

"Now we have everything we need to know to end the epidemic rise in blood pressure with age -- and high blood pressure -- in this country," says Jeremiah Stamler.

"We've known how to lower blood cholesterol since 1960. Now we know the same about blood pressure. So we can prevent both major diet-related risk factors for heart disease and stroke."

DASH-2 is already under way. It will test the combination diet at three levels of sodium intake: 3,450 mg, 2,300 mg, and 1,650 mg a day. "We want to see what bang you get for your buck when you combine the DASH diet with less salt," says Appel.

And who knows? Maybe someday, someone will compare the DASH diet to those recommended by Nathan Pritikin and Dean Ornish to see if their advice -- to cut fats and cholesterol even further, use only whole grains, and add little or no sugar -- yields even greater benefits.

But you needn't wait. Adding the DASH diet to the Big Four (see "The Bottom Line") is easy to follow, inexpensive, and not too strict.

"The beauty of DASH is that it doesn't take a genius to follow," says Norman Kaplan, a hypertension expert at the University of Texas Health Sciences Center in Dallas. "You just cut the fat, double your fruits and vegetables, and use low-fat dairy products."

What's more, the DASH has everything: fruits and vegetables to cut your risk of cancer, calcium to lower your risk of osteoporosis, and limits on saturated fat and cholesterol to cut your risk of heart disease.

"It's not a diet for one disease," says Appel. "It's a diet for all diseases."


COUNT THE NUTRIENTS

The DASH "Combination Diet" is low in cholesterol, high in fiber, potassium, calcium, and magnesium, and moderately high in protein. Here's how it compares with the DASH "Control Diet," which is closer to what the typical American eats. (Both diets supply 2,000 calories a day.)

Nutrient

DASH Combination Diet DASH Control Diet

Fat (% of cals.)

27 37

Saturated Fat (% of cals.)
6 16

Monounsaturated Fat (% of cals.)
13 13

Polyunsaturated Fat (% of cals.)
8 8

Carhohydrates (% of cals.)

55 48

Protein (% of cals.)

18 15

Cholesterol (mg per day)

150 300

Fiber (grams per day)

31 9

Potassium (mg per day)

4,700 1,700

Magnesium (mg per day)

500 165

Calcium (mg per day)

1,240 450

Sodium (mg per day)

3,000 3,000
SOURCE: DASH clinical study

THE BOTTOM LINE

If your blood pressure is optimal, following all of these Big Five proven strategies will help keep it from climbing as you get older. If your blood pressure is normal or high-normal, the Big Five may help lower it. If your pressure is high, the Big Five my enable you to use less -- or get off -- medication.

  1. Lose weight if you're overweight. Dropping as few as ten pounds can make a difference.
  2. Cut sodium to less than about 2,400 mg a day. Check labels for the lowest-sodium brands. Limit foods with 480 mg of sodium or more per serving. That's 20 percent of the Daily Value.
  3. Walk briskly, jog, swim, cycle, or do other aerobic exercise for 30 to 45 minutes a day at least three times a week.
  4. If you drink, keep it to no more than two servings of beer, wine, or liquor a day to keep blood pressure from rising. Women should limit themselves to one drink a day. Consuming more may increase the risk of breast cancer.
  5. Try a DASH-like diet. It should help reduce your risk of heart disease, stroke, cancer, osteroporosis, and diabetes.


The DASH Diet

It's not tough to follow the DASH diet. "Almost 100 percent of the participants completed the study," says researcher Lawrence Appel. Granted, when it came to food, all they had to do was eat. The researchers did all the planing, shopping, and cooking. Still, the foods weren't unusual -- no specialty foods with fat substitutes, nothing you couldn't buy at a local supermarket. (For detailed information about the DASH study, the results, and the diet, see the DASH's web page.)

Here's how many servings of which kinds of foods were in the DASH study's 2,000-calorie-a-day "Combination Diet" -- the one that lowered blood pressure the most.

Food and Servings Examples of 1 Serving Our Comments

Grains and grain products 7 to 8 a day

1 slice bread, half a cup dry cereal, half a cup cooked rice, pasta, or cereal Seven or eight servings a day seem like a lot, but they're small

Vegetables 4 to 5 a day

1 cup raw leafy vegetable, half a cup cooked vegetable, three quarter cup vegetable juice Eight to ten servings a day of fruits and vegetables tops the five to nine servings recommended by the National Cancer Institute's "5 A Day" program. The averae American is stuck at just over three.

Fruits 4 to 5 a day

three quarter cup fruit juice, 1 medium fruit, one quarter cup dried fruit, one half cup fresh, frozen, or canned fruit Ditto

Low-fat or non-fat dairy food 2 to 3 a day

1 cup skim or 1% milk, 1 cup low-fat yogurt, 1 and a half oz. part-skim or non-fat cheese Three servings a day is better to help reduce the risk of osteoporosis

Meats, poultry, & fish 2 or less a day

3 oz. broiled or roasted lean meats, skinless poultry, or fish We now average more than two servings a day, and they're often fatty: hamburgers, fried chicken or fish, or chicken with the skin.

Nuts, seeds, & bean 4 to 5 a week

one third cup nuts, 2 Tbs. sunflower seeds, half cup cooked beans Most people eat only two servings of beans a week. They're missing out on delicious lentil soups, Cuban black-beans-and-rice, Middle Eastern hummus, Mexican bean burritos, etc.

Added fats, oils, & salad dressing 2 to 3 a day

1 tsp. oil or soft margarine, 1 tsp. regular mayonnaise, 1 Tbs. low-fat mayonnaise, 1 Tbs. regular salad dressing, 2 Tbs. light salad dressing The "control" diet had six servings a day. Add your fats to vegetables, beans, breads, or other foods for flavor.

Snacks & sweets 5 a week

1 medium fruit, 1 cup low-fat yogurt, half cup low-fat frozen yogurt, three quarter cup pretzels, 1 Tbs. maple syrup, sugar, jelly, or jam, half cup Jell-O, 3 pieces hard candy, 15 jellybeans The healthier, the better. If you're more likely to go for the jellybeans than the fresh fruit, keeping your snacks to less than one a day minimizes the damage. The "control" diet had four snacks a day.

SOURCE: DASH clinical study

Nutrition Action Healthletter