Thu, Sep 24, 2009 page14

• [ HEALTH ] Too much salt takes a high toll on blood pressure

  Sedentary lifestyles, expanding waistlines and high salt intake increase risk of hypertension

  • By Jane E. Brody / NY TIMES NEWS SERVICE
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  Perhaps nothing in medicine more aptly depicts the paradoxical statement “doing better, feeling worse” than high blood pressure. Despite an extraordinarily easy way to detect it, strong evidence for how to prevent it and proven remedies to treat it, more Americans today have undetected or poorly controlled hypertension than ever before.

  The aging of the population is a reason but not the only one, said Aram Chobanian, a hypertension expert at Boston University Medical Center. As he summarized the problem in an interview and in The New England Journal of Medicine last month, Americans are too sedentary and fat. They eat too much, especially salt, but too few potassium-rich fruits and vegetables.

  The makers of processed and fast foods created and persistently promote a craving for high-salt foods, even in school lunch programs. And Americans without health insurance often don’t know that their blood pressure is too high because they wait for a calamity to strike before seeking medical care.

  Solutions to the blood pressure problem require broad-scale approaches — by the public, by government, by industry and by health care professionals. Several measures are similar to those that have been so effective in curbing cigarette smoking; others require better, affordable access to medical care for everyone at risk, including children and the unemployed. Still others need the cooperation of government, industry and the public to improve the American diet and enhance opportunities for health-promoting exercise.

  No one claims that the solutions are cheap. But failure to fix this problem portends even greater costs down the line, because uncontrolled hypertension sets the stage for astronomically expensive heart and kidney disease and stroke — diseases that will become only more common as the population ages.

  DOING THE NUMBERS

  Once, the prevailing medical opinion was that lowering an elevated blood pressure was hazardous because it would deprive a person’s vital organs of an adequate blood supply. But a few pioneering medical researchers thought otherwise and eventually showed that lowering high blood pressure could prevent heart attacks, heart failure, strokes and kidney disease — and save lives.

  Even then, it was long thought that the only important indicator was diastolic pressure — the bottom number, representing the pressure in arteries between heartbeats. Further studies showed that the larger top number, systolic pressure, representing arterial pressure when the heart beats, was also medically important.

  And as the various studies reached fruition, it became apparent that the long-accepted numbers for desirable blood pressure were too high to protect long-term health.

  Now the upper limit of normal blood pressure is listed as 120 over 80; anyone with a pressure of 140 over 90 or higher is considered hypertensive. Those with pressures in between are considered pre-hypertensive and should take steps to bring blood pressure down or, at least, prevent it from rising more.

  The change mirrors what happened with serum cholesterol, for which “normal” was once listed as 240 milligrams per deciliter of blood and is now less than 200 to prevent heart disease caused by clogged arteries.

  It was also long thought that blood pressure naturally rises with age. Indeed, the Framingham Heart Study showed that when 65-year-old people whose blood pressure was below 140 over 90 were followed for 20 years, about 90 percent of them became hypertensive because their arteries narrowed and stiffened with age, causing blood to push harder against artery walls.

  But in many societies where obesity is rare, activity levels are high and salt intake is low, blood pressure remains low throughout life. This is the best clue we have for the lifestyle changes needed to prevent illness and premature death caused by hypertension.

  Claude Lenfant, who served as director of the National Heart, Lung and Blood Institute, is 81 and has a blood pressure of 115 over 60, a level rarely found among older Americans not taking medication for hypertension. His secret: a normal body weight, 6 or more kilometers walking daily, and no salt used to prepare his meals, most of which are made from scratch at home.

  In an interview, Lenfant, who now lives in Vancouver, Washington, said the problem of hypertension was rising all around the world and added that by 2020 the number of people with uncontrolled hypertension was projected to rise 65 percent. One reason is that doctors today are more likely to diagnose the problem, so it is reported more often in population surveys. “But I’m much more concerned about the fact that so much high blood pressure is not controlled,” he said, and called “therapeutic inertia” an important reason.

  It is not enough for doctors to write a prescription and tell patients to return for a check-up in six months, he said. Rather, a working partnership between health care professionals and patients is needed to encourage people to monitor their pressure, adopt protective habits and continue to take medication that effectively lowers pressure.

  TREATMENT AND PREVENTION

  Diuretics are a first-line and inexpensive remedy, but many patients with hypertension also need other drugs to lower pressures to a desirable level.

  Chobanian, whose New England Journal report was titled “The Hypertension Paradox: More Uncontrolled Disease Despite Improved Therapy,” noted that “in the majority of patients, two or more antihypertensive drugs are required to achieve target blood-pressure levels.” In the interview, he emphasized the detrimental role played by diets high in salt and calories and low in protective fruits and vegetables — a result of portions that are too large, and of too many fast and processed foods that rely on salt to enhance flavor. “Generally, the average person in our society consumes more than 10g of salt a day,” Chobanian said, “but the Institute of Medicine recommends a third of this amount as optimal.”

  A new RAND Corp study finds that a one-third reduction in salt consumption could save US$18 billion a year in direct medical costs. Chobanian called for better food labeling; changes in foods served in cafeterias, restaurants and schools; and less advertising on children’s television of unhealthy foods high in fat, salt and sugar. Also needed are better opportunities for all people to get regular exercise. “We have to focus more on children,” he said. “They’re the ones who will be getting cardiovascular diseases in the future.”

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