Hypertension--Shaking the Salt Habit

May 2004
Volume III, Number 11

In his busy research at the VA Medical Center in Indianapolis, Dr. Howard Pratt, a member of Indiana Center for Vascular Biology and Medicine, focuses on the role of genetics in salt retention. Specifically, he is concerned with the impact of ethnicity in hypertension.

"We are investigating genes that encode for proteins involved in the retention of sodium by the kidney," explains Dr. Pratt, a professor at IU School of Medicine. "A number of sites within the kidney transport sodium from the urine back into the bloodstream--99 percent of the sodium filtered by the kidneys is returned to the blood. Our hypothesis is that certain sites within the kidney are too active with respect to their transport of sodium--keeping on board more than is good for us. If one retains too much sodium, there is a risk for hypertension."

Medical experts concur that Americans consume excessive quantities of sodium. According to the National Institutes of Health, 50 million Americans, or about one in four American adults (and an increasing number of obese adolescents), have high blood pressure. Consider that the recommended government guidelines call for no more than 2.4 grams of sodium a day, or about one teaspoon, for a healthy American adult, while the Institute of Medicine of the National Academy of Science concluded that 1.5 grams daily is sufficient for most individuals. The average consumer takes in about twice the recommended daily amount of sodium. A restaurant-prepared meal can deliver a whopping full day's quota of salt in a single sandwich.

"Sodium retention, or holding on to too much sodium, underlies much of the risk for hypertension in Western societies," Dr. Pratt believes. "Combine a diet that is high in sodium and calories, and there is even a greater likelihood for hypertension."

Along with the revitalized interest in (and more widespread appreciation of) salt and its role in hypertension, there is increasing evidence supporting the use of diuretics in treating patients with hypertension. Results from the landmark Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) found that diuretics that help rid the body of excess fluids and sodium work better than many newer medications to treat high blood pressure and prevent heart disease, though most hypertensive patients require more than one medication to control blood pressure.

"Diuretics alone may be all that are required for control of blood pressure," adds Dr. Pratt. "They certainly make the other blood pressure medications more effective. The results of the ALLHAT study were not surprising to many of us, but the trial did re-emphasize how important it is that physicians make use of diuretics in treating patients with hypertension."

While you can't change the kidney's capacity for holding onto sodium, you can consume less salt to reduce the risk of hypertension and/or complications of the disease.

Along with boosting one's physical activity and losing excess weight, increasing water intake may also help.

"There is new evidence that sodium excretion may be enhanced by drinking more water, which may modestly reduce the risk for hypertension," notes Dr. Pratt. "Whether that translates into sustained lowering of blood pressure is not as clear."

Reducing salt intake requires a little detective work on your part, as most of today's salt consumption comes from hidden sources (see below). Despite fast-food restaurants' attempts to lower the fat, calorie, and carbohydrate content of their products, salt reduction has not been a priority. In fact, to satisfy the consumer's taste buds, some companies have actually increased the salt content of their foods.

"Most people get into trouble not from using the salt shaker in excess," says Dr. Pratt, "but rather from the hidden sources, such as most any of the processed foods where sodium content is high."

You may send your questions about vascular problems to Dr. March, 1100 Waterway Blvd., Indianapolis, IN 46202. Answers will be published in future issues of this newsletter and at neighborhood-heart-watch.org. For more information about the work of ICVBM, log on to: vascularbiomed.iu.edu.

Where Is Sodium Found?

Canned and Frozen Foods

Fast Foods

Learn more about the Neighborhood Heart Watch program at www.neighborhood-heart-watch.org. This article © American Foundation for Preventative Medicine. All Rights Reserved.