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food for thought

Eating the right diet and getting regular exercise are effective strategies to lower elevated blood pressure.

Clinical trials have found this to be true in people with hypertension (high blood pressure) who don’t take blood-pressure-lowering drugs, as well as those who are treated with one or two medications.

What is the best diet to help with high blood pressure?

Yet among people with high blood pressure that doesn’t respond to drug therapy, called resistant hypertension, studies investigating the potential benefit of diet and exercise have been almost non-existent.

Until now.

A randomized controlled trial from Duke University School of Medicine in Durham, N.C., demonstrated that the combination of diet, reducing sodium intake and exercise led to significant blood-pressure-lowering effects in people with resistant hypertension.

What is resistant hypertension?

Hypertension, affecting almost one in four Canadians, is a leading preventable risk factor for heart disease, heart attack and stroke. Up to 30 per cent of people diagnosed with hypertension have resistant hypertension, defined as having a blood pressure reading that remains above target despite taking three or more blood-pressure-lowering drugs at optimal doses.

Over time, uncontrolled blood pressure is associated with a 50-per-cent greater risk of heart attack, stroke and cardiovascular death compared to controlled blood pressure.

About the new research

The TRIUMPH study, published on Sept. 27 in the American Heart Association’s journal Circulation, was the first to test the effect of comprehensive lifestyle modification on resistant hypertension. (TRIUMPH stands for Treating Resistant Hypertension Using Lifestyle Modification to Promote Health.)

For the four-month trial, 140 participants with resistant hypertension received either an intensive lifestyle intervention or standardized education and physician advice.

Those in the lifestyle intervention group were instructed how to follow the DASH diet with a calorie and sodium restriction. (DASH stands for Dietary Approaches to Stop Hypertension.) These participants also received feedback on their adherence to the diet during weekly 45-minute group sessions led by a dietitian and psychologist.

The lifestyle intervention also included 30 to 45 minutes of biking and/or walking (and eventually jogging) three times a week under the supervision of an exercise physiologist.

Participants in the comparison group attended a one-hour educational session and received DASH diet materials. They were also given weight-loss targets and exercise goals which they were to achieve on their own.

All participants adhered to their blood pressure medication regimens during the study.

After 16 weeks, both groups experienced a significant reduction in blood pressure, comparable to that seen with blood-pressure-lowering medications.

Participants in the intensive lifestyle intervention group, however, achieved the greatest reduction in blood pressure. They also lost significantly more weight over the study period, 15 pounds versus 8.5 for those in the comparison group.

Diet and exercise modifications are often recommended before starting a medication to lower blood pressure. These new findings demonstrate that they are also an effective strategy when medications alone are not doing enough to manage blood pressure.

What’s in the DASH diet?

The DASH diet, first proven to lower blood pressure in people with mild hypertension in 1997, focuses on fruits and vegetables, low-fat dairy products, and beans, lentils, nuts and seeds. These foods supply plenty of calcium, magnesium and potassium, minerals that help regulate blood pressure.

The diet plan also emphasizes whole grains and limits red meat and sweets. It also limits foods high in saturated fat such as fatty meats, high-fat dairy products, butter and coconut oil. Sodium intake is restricted to 1,500 to 2,300 milligrams per day. (One teaspoon of table salt contains 2,300 milligrams of sodium.)

The DASH diet advises specific daily or weekly servings of food groups depending on your calorie needs.

A 1,600-calorie DASH diet recommends, for example, eating three to four vegetable servings, four fruit servings, six whole grain servings, two to three low-fat dairy servings, three to six lean protein servings and two unsaturated oil servings daily. A serving of beans, lentils, nuts or seeds is recommended three times per week.

One serving is equivalent to one half-cup cooked vegetables or one cup salad greens, one medium-sized fruit or one half-cup fresh fruit, one slice whole grain bread or one half-cup cooked grains, one cup milk or yogurt, one ounce cooked fish or meat, one teaspoon vegetable oil or two tablespoons salad dressing and one-third-cup nuts or one half-cup cooked beans or lentils.

Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan. Follow her on Twitter @LeslieBeckRD

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