Major Breakthroughs In the Prevention and Treatment Of High Blood Pressure

The beginning of the new millennium was marked by the publication of the results of randomized clinical trials about two “breakthrough, novel and innovative” interventions for the prevention and treatment of high blood pressure. Randomized clinical trials are the scientific “gold standard” for assessing the effectiveness of all types of medical interventions. Neither of these breakthroughs requires a doctor’s visit nor a trip to the pharmacy. Both save rather than cost money and there are no known adverse effects associated with their use.

The first study was supported by the National Heart, Lung, and Blood Institute, a part of the National Institutes of Health, and was published in the January 2, 2001 issue of Annals of Internal Medicine. It was called Trials of Hypertension Prevention, Phase II (TOHP II) and involved 1,191 subjects who were randomly assigned to one of four intervention groups: (1) weight loss only; (2) salt (sodium) reduction, only; (3) combined weight loss and sodium reduction; and (4) as a control group usual care. Eligible participants were overweight adults who were not receiving drugs to treat high blood pressure or taking drugs that would increase their pressure. They had to have a diastolic blood pressure (lower number) of 83 to 89 millimeters (mm) of Mercury (Hg) and a systolic blood pressure (upper number) of less than 140 mm Hg.

Subjects assigned to the weight loss groups had a goal of losing 10 pounds during the first six months of the study. They started with an individual counseling session, and then attended 14 weekly group meetings led by dietitians or health educators, then six biweekly group meetings and finally monthly group meetings. In addition to cutting calories, physical activity was increased gradually to 30 to 45 minutes per day.

The average amount of weight lost for the weight loss groups was 9.7 pounds after six months, 4.8 pounds at 18 months, and at 36 months the amount of weight lost was 0.4 pounds. The average weight gained in the control group receiving usual care at the same times was 0.2, 1.5, and 4.0 pounds, respectively. This translated at 36 months to a 0.35 mm Hg reduction in diastolic and a 0.45 mm Hg reduction in systolic blood pressure per 2.2 pounds (one kilogram) of weight lost.

The researchers also assessed the likelihood of the trial subjects developing high blood pressure. High blood pressure was defined for the purpose of this study as a systolic pressure 140 mg Hg and a diastolic pressure of at least 90 mm Hg. Using this definition, those assigned to the weight loss group were significantly less likely than the controls receiving usual care to develop high blood pressure. The risk of developing high blood pressure at 6, 18, and 36 months and at the end of the study was reduced by 42, 22 , 19 and 21 percent, respectively in the weight loss group.

The second study was also supported in part by the National Heart, Lung, and Blood Institute and was published in January 4, 2001 issue of the New England Journal of Medicine. This trial goes by the acronym DASH standing for the Dietary Approaches to Stop Hypertension diet.

The DASH diet emphasizes fruits, vegetables, and low-fat dairy products. It includes whole grains, fish, poultry, and nuts, contains only small amounts of red meat, sweets and sugar containing drinks, and has decreased amounts of total and saturated fat and cholesterol. This type of diet has been shown previously to lower blood pressure in those with and without high blood pressure compared to a typical diet in the U.S.

Clinical trials have shown that limiting the quantity of salt in typical diets in the U.S. or northern Europe reduces blood pressure. Guidelines recommend reducing the amount of salt in the diet to one-fifth of an ounce (5.8 grams of sodium chloride, 1 ounce = 28.35 grams) a day.

The researchers wanted to know if reducing the level of salt from the average American diet of 8.7 grams to below the currently recommended upper limit of 5.8 grams would reduce blood pressure more than reducing salt intake only to the recommended limit of 5.8 grams.

Participants, 412 in total, were randomly assigned to eat either a typical U.S. diet or the DASH diet. Within each group the participants ate food with high, intermediate, and low levels of salt for 30 consecutive days, in random order.

Participants assigned to the DASH diet showed a significantly lower systolic blood pressure at each level of salt intake (high, intermediate, low). The difference was the greatest with high salt intake compared to low salt intake. Blood pressure can be lowered in both those on a typical U.S. diet and the DASH diet by reducing salt intake.

Another remarkable finding from this study was that according to the study’s authors, in participants with high blood pressure, the combined effects of the DASH diet plus a low level of salt intake were greater than or equal to treatment with any of a variety of different single high blood pressure lowering drug. It is equally remarkable that the effects seen in this trial took place in only 30 days. The combination of low salt intake with the DASH diet was well tolerated by the participants.

It is unlikely that you will see direct-to-consumer TV ads or glossy magazine promotions touting weight loss and reducing daily salt intake to treat or prevent high blood pressure because the only one that would profit from these steps is you.

What You Can Do

You may be able to prevent on your own or treat your high blood pressure, in consultation with your doctor, by instituting the type of dietary lifestyle changes tested in these two clinical trials.