High Blood Pressure THE END OF AN EPIDEMIC?
A new study, called DASH-Sodium, has made it clear that a healthy diet can keep blood pressure from rising as quickly as it does on a typical American diet. DASH (Dietary Approaches to Stop Hypertension) caps decades of research on how foods, salt, exercise, and weight affect blood pressure.
"We now have all the science we need to end the hypertension epidemic," says Jeremiah Stamler of Northwestern University Medical School in Chicago.
The DASH diet isn't complicated, Spartan, or built around unusual foods, And it may also cut the risk of cancer and osteoporosis.
Death rates from heart disease and strokes have plummeted over the last 25 years. And while the two diseases still kill 635,000 Americans a year, that's roughly half the 1970 death rate. That's partly because we've gotten better at lowering blood pressure and blood cholesterol through diet and drugs and at getting people not to smoke. We've also gotten better at treating heart attacks and strokes when they occur.
Nevertheless, heart disease is still the number-one killer and stroke is still the number-three killer in the U.S. (cancer is number two). High blood pressure is a major risk factor for both.
When Normal Isn't Good Enough
If your blood pressure isn't high, don't assume it's low enough to ignore. Only one out of two adults has "optimal" blood pressure (see "What's Your Pressue?"). Two out of four have "high," "high-normal," or "normal" blood pressure. Despite the comforting sound of "normal," that level is elevated enough to raise the risk of a heart attack or stroke (see "The Risk of Being Normal"). And, chances are, normal or high-normal will creep up to high as you get older.
Why not wait until then to deal with your blood pressure? Here are three good reasons:
1. You might die first. Hypertension has no symptoms. Many people learn that they have high blood pressure only when they have a stroke or heart attack. Others never hear the diagnosis. "In about 25 percent of untreated patients, the complication of hypertension will be sudden death," says Paul Whelton, vice president of Tulane University School of Public Health and Tropical Medicine in New Orleans. Many others are diagnosed before a stroke or heart attack, but by then the excess pressure in their blood vessels has already damaged their heart, eyes, kidneys, or brain.
2. Your risk never goes back to where it was. Treating high blood pressure lowers your risk of a heart attack or stroke, but only so much. "Under the best circumstances, a treated patient has twice the risk of a heart attack or stroke of someone who never had high blood pressure," says Whelton.
3. It's a life sentence. Once it's diagnosed, hypertension has to be monitored--and often treated with drugs--for the rest of your life. And medication means more expense, more inconvenience, and possible side effects like sexual impotence.
That's why researchers are so keen on preventing high blood pressure. But most people don't know how.
The So-Called Great Debate
Name four soft drinks. Good. Now name four ways to prevent high blood pressure. Having trouble?
It's been seven years since the National Heart, Lung, and Blood Institute released its Working Group Report on the Primary Prevention of Hypertension. Yet few people can rattle off its findings.
The Working Group, chaired by Whelton, came up with several strategies to keep blood pressure low (see "The Bottom Line"). Three of them--lose (or keep from gaining) excess weight, get regular exercise, and limit or avoid alcoholic beverages--caused little or no ruckus. A fourth--eat less salt (sodium chloride)--fueled what some called the "Great Debate."
"It was a false, synthetic debate created by special interests, just like the Tobacco Institute nurtured the so-called debate over the dangers of smoking," says Northwestern University professor emeritus Jeremiah Stamler. By the time the Working Group released its report, hundreds of studies of animals and people had already convinced most experts that sodium was a blood-pressure booster.
At the same time, Whelton's group concluded that it was too early to say whether a number of other steps--like consuming more potassium, calcium, magnesium, protein, or fiber or cutting fat and cholesterol--could lower blood pressure. For all practical purposes, the first DASH study settled those questions. Then the second DASH Study, DASH-Sodium, tackled salt.
"When the late 20th-century and early 21st-century history of medical research is written," says Stamler, "DASH and DASH-Sodium will go down as landmark studies."
The first DASH was launched to solve a puzzle. Researchers had noticed that people who ate diets rich in potassium, calcium, magnesium, protein, and fiber had low blood pressure. But when the scientists actually gave people calcium, magnesium, or other supplements, only potassium consistently made a dent in the participants' blood pressure.
"The scientific literature was confusing," says Lawrence J. Appel, a DASH researcher at Johns Hopkins University in Baltimore.
So instead of testing each nutrient separately, they went back to the big picture. "We decided to test the whole diet, not supplements," says Frank Sacks, a cardiovascular researcher at the Harvard School of Public Health who participated in DASH.
DASH was an eight-week study of 459 adults with normal, high-normal, or high blood pressure. Each was randomly assigned to eat one of three diets, all prepared by DASH dietitians:
* The "usual" diet had average levels of fat and cholesterol and below-average levels of potassium, magnesium, and calcium.
* The "fruit and vegetable" diet was identical to the usual diet, except that eight to ten servings of fruits and vegetables a day replaced most snacks and sweets. That bumped up the potassium, magnesium, and fiber.
* The "combination" diet cut fat, saturated fat, and cholesterol while upping not only fruits and vegetables (in place of snacks and sweets), but low-fat dairy foods (all of which meant more potassium, magnesium, fiber, protein, and calcium).
Calories (adjusted to keep the participants from gaining or losing weight), alcohol (limited to a drink or two a day), and sodium (kept at 3,000 milligrams a day) were the same in all three diets, so they weren't an issue. (Before entering the study, the participants in the DASH study averaged roughly 3,500 mg of sodium a day.)
The results, reported in 1997, were indisputable: The combination diet knocked down average blood pressures the most: by 5.5 points (systolic) over 3.0 points (diastolic). Blood pressure fell whether the participants were men or women, black or white, or whether or not they had hypertension.
Which nutrients deserved the credit? "We couldn't tease out the individual effects," says Stamler.
For example, "magnesium, potassium, and fiber all come from fruits and vegetables," he explains. "But it's difficult, if not impossible, to separate out the contribution of each."
No matter. "We could spend the next 100 years working out the mechanisms, but from a public health point of view, it doesn't mean a hoot," says Stamler.
What does matter is that a diet rich in fruits and vegetables, with low-fat dairy foods, seafood, and only lean meats and poultry, lowers blood pressure dramatically (see "A Typical Dash Menu").
To researchers, DASH was an effective new tool to lower blood pressure. To the salt industry, DASH was an excuse to let salt off the hook.
"The evidence mounts that sodium is a `bit player' in the drama of diet and hypertension," charged the Salt Institute in response to the study's release.
And then came DASH-Sodium.
The Definitive DASH
Researchers designed DASH-Sodium to see if blood pressure could be lowered further by eating a DASH diet and cutting sodium. They also aimed to end the salt controversy. "We were interested in doing a definitive study," says Harvard's Frank Sacks, who chaired the DASH-Sodium Steering Committee.
Of the 412 men and women in DASH-Sodium, about 40 percent had hypertension, while 60 percent had normal or high-normal blood pressure. "The people we tested represent 50 percent of all adults and 80 percent of all middle-aged and older adults," says Sacks.
The participants were randomly assigned to eat either a DASH combination diet (now simply called the "DASH diet") or a usual diet for 12 weeks. But the sodium in both diets was changed every four weeks to one of three levels: a "higher" intake of 3,300 mg a day, an "intermediate" intake of 2,400 mg a day, or a "lower" intake of 1,500 mg a day.
Once again DASH scored a home run: On both the DASH and the usual diets, the lower the sodium fell, the lower blood pressures fell. "I was surprised at the magnitude of the effect," says Sacks, "especially when you go from the intermediate sodium intake--which matches the government's current guidelines--to the lower level."
For the group as a whole, the DASH diet with the lowest sodium intake (1,500 mg a day) cut blood pressure by an impressive 8.9 points (systolic) over 4.5 points (diastolic) compared to the usual diet with the higher sodium intake (3,300 mg a day). That was roughly twice the impact of the DASH diet alone. As expected, blood pressure fell more in people with hypertension (11.5 points systolic) than in those without (7.1 points). (More details will be available when the study is published.)
"This study unequivocally shows how important it is for people with or without hypertension to cut salt," says Stamler.
But getting there isn't easy.
Salt, Salt Everywhere ...
Cutting back to 1,500 mg of sodium a day isn't about tossing your salt shaker (though that wouldn't hurt). It's about avoiding the massive amounts of sodium that manufacturers dump into our food before it reaches the table. (Salt in processed foods and restaurant fare accounts for more than 75 percent of the sodium we consume.)
And it's not just a matter of skipping salty snacks like potato chips and fries. A serving of Cheerios has more sodium than a serving of potato chips. Any burger on McDonald's menu has more sodium than its super size French Fries. Frozen dinners, pizza, lunch meats, processed cheese, and canned or ramen noodle soups are just a few of the many offenders (see "The Sodium Scoreboard").
Even bread--because it's such a staple-is a major source of sodium. Yet bread rarely tastes salty. The bottom line is that you need a food label, not your taste buds, to tell how much sodium you're getting. And in restaurants, where there are no labels, the sodium numbers are staggering.
The lowest you can expect when you eat out at most restaurants is roughly 1,000 mg of sodium, and that's for a simple meal, like grilled chicken breast or steak plus salad (with dressing) and a baked potato. Even a tuna salad sandwich has 1,300 mg. An appetizer like Buffalo wings or flied mozzarella sticks hovers around 1,800 mg--that's more than the ideal "lower" level in an entire day's DASH-Sodium diet.
Yet, those aren't the highest numbers.
Just about any meal you order in a Chinese or Mexican restaurant will supply at least 2,000 mg of sodium (beef with broccoli and house lo mein top 3,000 mg). And an order of cheese flies clocks in at 4,000 mg. With ranch dressing it nearly hits 5,000 mg.
"We need firm, steady persuasion on the food industry to incorporate less salt into our food both in restaurants and supermarkets," says Stamler. "The food industry needs to straighten up and fly right."
But that doesn't mean that you can't cut sodium from your diet. It may not be easy, but it's not impossible either.
On Your Own
The DASH participants didn't have to scour labels, interrogate waiters, or revamp recipes to keep their salt in check. All their food was prepared for them by DASH dietitians. But other studies, like the Trial of Nonpharmacologic Interventions in the Elderly (TONE), have demonstrated that people can cut sodium on their own.
"The TONE study is one of the best demonstrations of the feasibility of cutting sodium in the real world," says hypertension expert Norman Kaplan of the University of Texas Health Sciences Center in Dallas.
Researchers took 975 men and women aged 60 to 80 off their blood-pressure-lowering medication. The 390 who weren't overweight were randomly assigned to either eat less salt or get "usual care" (that is, they were invited to attend meetings on topics that had nothing to do with the study). The 585 who were overweight were randomly assigned to reduce their salt intake, lose weight, do both, or get usual care.
"Only 16 percent of the overweight usual care group was able to stay off medication," says Kaplan. "But about 35 percent of those who either lost weight or cut sodium--and 44 percent of those who did both--kept their blood pressure down with no drugs." Among those who weren't overweight, 24 percent of those on usual care and 38 percent of those who cut salt were able to stay off drugs.
And that's without a salt-free or starvation diet. On average, the participants cut their sodium by only about 900 mg a day--they started at about 3,400 mg--and lost an average of just nine pounds. Only about 40 percent of the volunteers dropped their sodium intake as low as the study's 1,800-mg target.
"They modified their diets in a sensible way," says Kaplan. "It's not beyond our ability. We can make an impact on blood pressure and that can translate into prevention."
WHAT'S YOUR PRESSURE?
Blood pressure that increases the risk of disease SYSTOLIC DIASTOLIC HIGH 140 or above or 90 or above 140 90 HIGH-NORMAL 130 to 139 or 85 to 89 130 85 NORMAL 120 to 129 or 80 to 84 120 80 OPTIMAL below 120 and below 80
If your systolic and diastolic pressures fall into different categories, your risk depends on the higher category.
Numbers apply to adults who aren't taking drugs to lower their blood pressure.
Source: National Heart, Lung, and Blood Institute.
The DASH Diet
It wasn't tough for people in the DASH study to follow the DASH diet. Granted, when it came to food, all they had to do was eat. The researchers did all the planning, shopping, and cooking. Still, the foods weren't unusual--nothing you couldn't buy at a local supermarket (see "A Typical DASH Menu").
Here's how many servings of which kinds of foods were in the first DASH study's 2,000-calorie-a-day "Combination Diet." You can turn it into a lower-salt DASH diet by choosing lower-salt versions of breads, cereals, nuts, salad dressings, vegetable juices, and other foods.
Food & Servings Examples of 1 Serving Grains & grain products 1 slice bread 7 to 8 a day 1/2 cup dry cereal 1/2 cup cooked rice, pasta, or cereal Vegetables 1 cup raw leafy vegetables 4 to 5 a day 1/2 cup raw non-leafy vegetables 1/2 cup cooked vegetables 3/4 cup vegetable juice Fruits 3/4 cup fruit juice 4 to 5 a day 1 medium fruit 1/2 cup fresh, frozen, or canned fruit 1/4 cup dried fruit Low-fat or non-fat 1 cup fat-free or 1% milk dairy foods 1 cup low-fat yogurt 2 to 3 a day 1 1/2 oz. non-fat cheese Meats, poultry, & fish 3 oz. broiled or roasted lean meat, 2 or less a day skinless poultry, or seafood Nuts, seeds, & beans 1/2 cup cooked beans 4 to 5 a week 1/3 cup nuts 2 Tbs. sunflower seeds Added fats, oils, 1 tsp. oil or soft margarine & salad dressings 1 tsp. regular mayonnaise 2 to 3 a day 1 Tbs. low-fat mayonnaise 1 Tbs. regular salad dressing 2 Tbs. light salad dressing Snacks & sweets 1 medium fruit 5 a week 1 cup low-fat yogurt 1/2 cup low-fat frozen yogurt 3/4 cup pretzels 1 Tbs. maple syrup, sugar, jelly, or jam 1/2 cup Jell-O 3 pieces hard candy 15 jellybeans
Source: DASH study.
A Typical DASH Menu
Here's a sample menu from the DASH-Sodium study. The DASH dietitians kept the sodium low--less than 1,500 mg for the day--by limiting processed foods. If you can't keep your salt down every day, especially when you eat in restaurants, don't give up. You can still help keep a lid on your blood pressure by following the basic DASH diet (see "The DASH Diet") and cutting salt whenever possible.
Sodium (milli- Servings grams) Breakfast Shredded wheat cereal (112 cup) 2 1 grain Skim milk (1 cup) 130 1 dairy Orange juice (1 cup) 5 1 fruit Banana (1 medium) 1 1 fruit 100% whole-wheat bread (1 slice) 150 1 grain Lunch Chicken Salad(*) (3/4 cup) 150 1 poultry 100% whole-wheat bread (2 slices) 300 2 grains Dijon mustard (1 tsp.) 130 -- Tomato (2 large slices) 5 1/2 vegetable Mixed cooked vegetables (1 cup) 25 2 vegetables Fruit cocktail, juice pack (1/2 cup) 5 1 fruit Dinner Spicy Baked Cod(*) (3 oz.) 90 1 fish Green snap beans, cooked from frozen, without salt (1 cup) 10 2 vegetables Baked potato with skin (1 large), without sail: 20 1 vegetable Low-fat sour cream (2 Tbs.) 30 1 fat Chives or scallions (1 Tbs.) 0 Fat-free cheddar cheese (3 Tbs.) 170 1 dairy Tossed salad with mixed 30 1 lb greens (1 1/2 cups) vegetables Olive-oil-and-vinegar dressing (2 Tbs.) 0 1 oil Snack Orange juice (1/2 cup) 3 1 fruit Almonds, dried, blanched, 3 1 nuts, without salt (1/3 cup) seeds, etc. Raisins, seedless (1/4 cup) 5 1 fruit Yogurt, blended, fat-free, with sugar (1 cup) 100 1 dairy
This one-day menu provides: 2,010 calories, 5 servings of fruits, 7 servings of vegetables, 3 servings of dairy foods, 59 grams of fat, 120 milligrams of cholesterol, and 1,360 milligrams of sodium.
(*) For recipe, see "Dashing Recipes," p. 7.
Source: National Heart, Lung, and Blood Institute.
3 1/4 cups chicken breast, cooked and cubed 3 Tbs. light mayonnaise 1/4 cup celery, chopped 1 Tbs. lemon juice 1/2 tsp. onion powder
Mix all ingredients in a large bowl. Makes five 3/4-cup servings.
Spicy Baked Cod
1 lb. cod (or other fish fillet), fresh or thawed from frozen 1 Tbs. olive oil 1 tsp. spicy seasoning mix (see below)
Preheat the oven to 350 [degrees] F. Spray a small baking dish with cooking oil spray. Wash and dry the cod. Place it in the dish and drizzle it with the oil/seasoning mix. Bake, uncovered, for 12 minutes or until the fish flakes with a fork. Cut into four pieces. Makes four servings.
Spicy seasoning mix: Mix together the following ingredients and store in an airtight container (use the rest for other recipes): 1 1/2 tsp. each white pepper and dried thyme, l/2 tsp. each cayenne pepper, black pepper, and onion powder, 1 1/4 tsp. garlic powder, and 1 Tbs. dried basil.
Source: National Heart, Lung, and Blood Institute.
COUNT THE NUTRIENTS
The DASH "Combination Diet"--which lowered blood pressure dramatically--is low in total fat. saturated fat. cholesterol, and sweets; high in fiber, potassium, calcium, and magnesium; and moderately high in protein. Here's how it compares with the DASH "Usual Diet." which is closer to what the typical American eats. (These numbers are for a diet that supplies 2,000 calories a day, but calories were adjusted to keep the DASH study participants from gaining or losing weight.)
DASH DASH Nutrient Combination Usual Diet Diet Total fat (% of cals.) 27 37 Saturated fat (% of cals.) 6 16 Monounsaturated fat (% of cals.) 13 13 Polyunsaturated fat (% of cals.) 8 8 Carbohydrates (% 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
Source: N. Eng. J. Med. 336: 1117, 1997.
THE BOTTOM LINE
Here are five strategies to help lower your blood pressure or to keep it from creeping up as you age.
1. Lose weight if you're overweight (and avoid gaining weight if you're not). Dropping as few as ten pounds can make a difference.
2. Cut sodium to less than 2,400 mg a day--and preferably less than 1,500 mg. Check labels for the lowest-sodium brands.
3. Walk briskly, jog, swim, cycle, or do other aerobic exercise for 30 to 45 minutes on most days.
4. If you drink, keep it to no more than two servings of beer, wine, or liquor a day. Women should limit themselves to one drink a day.
5. Try a lower-salt DASH diet. It should help reduce your risk of heart disease, stroke, cancer, osteoporosis, and diabetes.
FOR MORE INFORMATION
For more menus, recipes, and eating tips, see the Web sites of the National Heart, Lung, and Blood Institute (www.nhlbi.nih.gov/hbp/consumer/hearthealth/eating.html) and the DASH study (dash.bwh.harvard.edu/). Or write: Dash Study, NHLBI Information Center, P.O. Box 30105, Bethesda, Maryland 20824-0105. Keep in mind that menus and recipes for the first DASH study, which may still appear on those sites, may contain more sodium than those used in the DASH-Sodium study.
 Arch. Intern. Med. 153: 186, 1993.
 N. Eng. J. Med. 336: 1117, 1997.
 J. Amen Med. Assoc. 279: 839, 878, 1998.
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|Title Annotation:||Dietary Approaches to Stop Hypertension program|
|Publication:||Nutrition Action Healthletter|
|Article Type:||Statistical Data Included|
|Date:||Dec 1, 2000|
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