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Tackling high blood pressure.

Tackling High Blood Pressure

Each year, roughly 1.5 million Americans--half under age 65--have heart attacks. Another half million suffer strokes. High blood pressure, or hypertension, contributes to both. According to some estimates, the "silent killer" affects 60 million people--one out of every three adults. Among those over 65, it's one out of two.

Enter Norman Kaplan. The nationally known expert at the University of Texas Southwestern Medical School in Dallas has made a career out of studying and fighting high blood pressure.

While some people need drugs to lower their blood pressure, says Kaplan, millions can do it through diet.

Few people know as much about high blood pressure as Norman Kaplan, Head of the Hypertension Section at the University of Texas Southwestern Medical School. Kaplan has written more than 300 scientific papers, and he served on the Third and Fourth Joint National Committees on the Detection, Evaluation, and Treatment of High Blood Pressure. His books include Clinical Hypertension, Prevention of Coronary Heart Disease, Prevent Your Heart Attack, and Hypertension. His latest book, Travel Well, co-authored by his wife, Audrey, lists restaurants in 44 cities that will help diners keep their blood pressure and cholesterol down.

NAH's Bonnie Liebman spoke with him from CSPI's office in Washington, D.C. Q: In the past, doctors were concerned that high blood pressure was going untreated. Are people now being overtreated? A: Yes. To begin with, the diagnosis is being made too quickly, and many people are being diagnosed as having high blood pressure when, in fact, they don't. In a recent study, researchers used automatic monitors to measure the blood pressures of almost 300 hypertensives. The monitoring was done outside the doctor's office, while the people were working, riding subways, and going about their daily lives in New York City. The study showed that about 20 percent of them only had high blood pressure when it was measured in the doctor's office. A lot of hypertensive people probably only have what we call "office hypertension." Q: How can people tell if they really have high blood pressure? A: People should be aware that a single blood pressure measurement isn't enough. They should get multiple readings. We're also doing a lot more home blood pressures. Consumer Reports (August, 1987) did a story on devices that measure blood pressure at home. I firmly believe it's a technique we ought to be pressing people to perform.

DRUGS Q: Once the diagnosis is made, do physicians feel compelled to treat high blood pressure? A: They often do. Most physicians say, "why bother to make a diagnosis if you're not going to do something?" Doctors are simply trying to help people reduce their risk of heart attack and stroke, but they often don't realize that most people with fairly mild hypertension are not at that big a risk. In fact, physicians often could simply monitor the patient's blood pressure and use dietary approaches before they jump to medication. Q: Why are some doctors so eager to prescribe drugs? A: A lot depends on the physician's and the patient's time and energy. It's easier to write out a prescription and give it to the patient than to spend a half hour discussing why he or she needs to go on a diet, start exercising, or cut back on alcohol.

Also, the doctor knows the medication will work. That's not necessarily true for sodium restriction or cutting back on drinking. Not all people who make those changes have a significant fall in blood pressure. So the assumption is that we can't depend on these non-drug approaches, while we know medication will be effective. Q: Don't drugs have adverse effects? A: We're now increasingly aware of the hidden toxicities of drugs. Diuretics are the largest selling high blood pressure drug. Over fifty million prescriptions were written last year. We know that chronic use of diuretics may raise cholesterol for a significant number of patients by five to ten percent. That's about 20 points.

Also, diuretics cause blood sugar levels to become elevated in some people and potassium to fall in about one-third of patients. So we have a number of problems with diuretics--which is not to say they should be thrown out. Rather, we should use them more judiciously. For example, we used to give up to 200 mg. of the most common form of diuretics, hydrochlorothiazide. Now we know that one-twentieth, or 10 mg., may be enough. Q: What about other blood-pressure-lowering drugs? A: Over thirty million prescriptions for beta-blockers were written last year. These medications can cause HDL ["good"] cholesterol to decline.

So while we're lowering blood pressure, we're creating conditions that increase another risk factor. It doesn't happen to every patient, but it can happen, and a lot of people are taking these drugs without being aware of the potential problems.

SODIUM Q: How effective are non-drug treatments, such as low-salt diets? A: About 50 percent of the people who cut their sodium in half will have a significant fall in blood pressure. Studies find an average drop of about 5-over-4 mm. of mercury (Hg). That's not a big-league fall, but it's significant.

Three-fourths of all people with high blood pressure have mild hypertension--that is, their blood pressure is between 140 to 150 over 90 to 100 mm. Hg. It's these people who ought to try non-drug therapies, because they're the ones who are often going to have enough of a drop to bring their blood pressure down to normal. Q: Does a young person with normal or low blood pressure have to worry about sodium? A: If we could be sure they wouldn't develop hypertension, no. If someone in your family has hypertension or if you're overweight, we know you have a significantly greater likelihood of developing hypertension. But we have no good marker to determine who is sodium-insensitive and therefore doesn't have to worry. That's why a population-wide push to cut down on sodium makes the most sense. Q: What did we learn from the recent "Intersalt" study that compared sodium intakes and blood pressures in several countries? A: Those who don't like sodium say it proves their point. Those who like sodium say the same.

The study found that there was no difference in blood pressure between populations that consumed a lot or a little sodium. But that was only true after researchers excluded populations that consumed very little sodium, and I don't think that's fair.

What's more, in populations with higher sodium intakes, blood pressures rose more steeply as people aged. In populations with lower sodium intakes, blood pressures didn't rise as high as people got older.

If blood pressure didn't rise with age in the U.S., hypertension would no longer be a major public health problem. In other words, if we consumed less sodium, it would make a difference.

The study does suggest that beyond a threshold of two grams [2,000 mg.] of sodium per day, it probably doesn't matter how much you consume. Now, that's true as far as the development of hypertension is concerned, and if you look at large populations. On the other hand, if you cut an individual's intake down from four grams to two, in many cases you will see a positive effect.

POTASSIUM Q: Is potassium getting too little credit for its role in lowering high blood pressure? A: Potassium does need more attention. We don't have as much evidence for potassium as for sodium, but there are a number of good studies showing that adding about 2 to 3 grams of potassium to a diet that already has about that much potassium can lower blood pressure by 3 to 5 mm. Hg. Louis Tobian at the University of Minnesota has shown that potassium protects against kidney damage and strokes in animals.

I tell people not to take potassium tablets, but to eat more natural, unprocessed foods--anything that comes out of the ground. Nature never intended us to eat a lot of sodium, because all foods--fruits, vegetables, meats, grains--are low in sodium. Only when they're processed do we leach out the potassium and add the sodium.

CALCIUM & MAGNESIUM Q: How good is the evidence that calcium lowers blood pressure? A: It's a major controversy. In most studies, adding 800 to 1,500 mg. of calcium lowers blood pressure by about 5 mm. Hg in one-third or less of the patients. No one has found that all patients respond.

David McCarron, of the Oregon Health Sciences University in Portland, is calcium's major advocate, and his research is heavily supported by the National Dairy Council.

But I don't think giving calcium supplements has been documented as useful in lowering blood pressure.

As for epidemiological evidence, most of the careful analyses of the National Health and Nutrition Examination Survey data say low calcium intakes are not linked to high blood pressure, except for black males.

Furthermore, we have no rationale that would explain why more calcium would lower blood pressure. On the contrary, we expect calcium to tighten blood vessels and contract the heart.

The only exception may be people who excrete extra calcium in their urine. That may lower blood calcium, which would increase the levels of parathyroid hormone, which in turn could raise blood pressure.

Giving these people calcium might do something. But they probably comprise no more than 30 percent of those with high blood pressure. And keep in mind that extra calcium could increase the risk of kidney stones in people who are already excreting calcium in their urine. Q: Is there any evidence that magnesium lowers blood pressure? A: In well-controlled studies, magnesium doesn't seem to have an effect. Q: How important is the link between obesity and high blood pressure? A: Being even slightly overweight can increase the risk of hypertension, especially for the upper-body obese--those people with excess fat mainly in their abdomen and chest. The simplest way to tell if you've got upper-body obesity is to divide your waist measurement by your hip measurement. If the number is higher than 0.85, you're at risk.

I'm a good example. Even though I haven't gained much weight, and I'm not overweight, over the years my weight has shifted to my waist. My ratio is 0.94, which puts me above the risky level.

I never thought my waist was a health problem, only a social one. I've taken it as a personal challenge to start a better diet and exercise program. Q: Why should a paunch put you at greater risk than chubby thighs or hips? A: Abdominal fat is metabolically different than fat that's stored in the thighs and hips. Lower-body fat is largely inactive, except during pregnancy and lactation, when the thighs serve as a depot for fat stores that are used to make milk.

In contrast, upper body fat is active--that is, it is more readily released from the cells into the bloodstream, where it can clog arteries. The fat can also enter the liver, where it may interfere with the body's ability to get rid of insulin. That increases insulin levels in the blood, which turns out to raise blood pressure.

ALCOHOL AND FIBER Q: How does alcohol affect blood pressure? A: Social drinking can raise blood pressure. One or two drinks a day is okay, but with more than two drinks-- about an ounce of alcohol--you begin to see effects on blood pressure. Q: What about polyunsaturated fats or fiber? A: We don't have enough data to say they lower blood pressure. My advice is to eat less saturated fat and more fiber, but for other reasons.
COPYRIGHT 1989 Center for Science in the Public Interest
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Author:Liebman, Bonnie
Publication:Nutrition Action Healthletter
Article Type:interview
Date:May 1, 1989
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