Diet can make a difference to high blood pressure. It’s one of several lifestyle approaches—including not smoking, maintaining a healthy weight, getting moderate exercise, and practicing relaxation techniques—that can help reduce blood pressure or keep it in check. That’s good news since blood pressure rises with age: People over 55 have a 90 percent chance of developing hypertension, which raises the risk for heart disease, stroke, and kidney damage. But lifestyle changes might tip these odds. In countries where a mostly vegetarian diet is eaten, with little fat, salt, and sugar, blood pressure readings are lower. I’ll discuss some other ways that foods and beverages can help control high blood pressure.
I think the DASH diet or Dietary Approaches to Stop Hypertension is a well-researched eating plan that’s been proven to work (nhlbi.nih.gov/health-topics/dash-eating-plan). It emphasizes readily available foods, including fruits, vegetables, and low-fat dairy products (you can substitute calcium-fortified soy milk or tofu products for dairy), and it’s low in saturated and total fat. These foods are also rich sources of key nutrients thought to be effective in lowering blood pressure: The minerals calcium, potassium, and magnesium as well as fiber are all believed to influence hypertension, although their exact roles in this process aren’t clear.
The first DASH trial involved 459 adults, who were given one of three diets for eight weeks: The control group received a “typical American diet,” another ate this diet but with more fruits and vegetables, and a third followed the DASH plan. Hypertensive people on the DASH diet had the greatest reductions in blood pressure, with systolic pressure (the first number in a reading) dropping an average of 11 points and diastolic by 5 points. These reductions are similar to those achieved with blood pressure drugs (New England Journal of Medicine, April 17, 1997).
I think people with prehypertension (systolic pressure between 120 and 139, diastolic 80 to 89) or those with Stage 1 hypertension (systolic 140 to 159, diastolic 90 to 99) might bring down blood pressure primarily through diet and lifestyle changes. If on blood pressure medications, lifestyle approaches might help reduce dosages or the number of drugs taken.
Roughly half the people with high blood pressure are thought to be salt sensitive, meaning that consuming too much salt can elevate blood pressure while limiting salt might lower it. Researchers investigated whether an eating plan with high levels of sodium (3,300 mg a day), medium levels (2,400 mg), or low levels (1,500 mg) would cause the biggest drop in blood pressure. The greatest reductions were seen in people with high blood pressure on the low-sodium plan, whose systolic pressure fell nearly 12 points after 12 weeks (New England Journal of Medicine, January 4, 2001).
Salt might not be a major contributor to hypertension, but most Americans get too much. The latest government recommendations encourage everyone to keep their sodium levels to 1,500 mg a day. To cut back, eat less processed and fast food, use less table salt, and read food labels carefully.
The DASH diet is rich in carbohydrates, so one recent study modified its carbohydrate content to learn how this affected heart health. One group ate meals in which 10 percent of the carbohydrate calories were shifted to protein-rich foods like beans and egg whites, another group shifted 10 percent of carbs to monounsaturated fats, like olive or canola oil, while a third followed the standard DASH plan. After six weeks, all three diets cut blood pressure and other heart disease risk factors, yet researchers were surprised to find that both the protein-enhanced and higher-fat versions produced additional reductions in blood pressure among people with hypertension (Journal of the American Medical Association, November 16, 2005). These findings suggest that the DASH diet can be further improved by replacing some carbohydrates with either plant or lean protein or healthier fats.
Other dietary factors.
If you’re overweight, shedding five to 10 percent of your body weight can ease your heart’s workload and lower blood pressure significantly. For every two pounds of weight lost, blood pressure falls 1 point. As for alcohol, one drink a day for women or two for men may protect the heart, but more than this can increase your odds for hypertension. And while the latest study of caffeine consumption found that blood pressure was raised in women who drank the most cola but not coffee, I still suggest limiting your coffee, tea, and sodas to get less of this heart stimulant.
DASH Diet at a Glance
This eating plan contains nutrients that reduce hypertension and is now a standard part of treatment guidelines in the United States and abroad.
Servings*: 6 daily
Sample serving: one slice bread; 1/2 c cereal, cooked rice, or pasta
Servings: 4 daily
Sample serving: 1 c leafy greens; 1/2 c cooked veggies; 3/4 c vegetable juice
Servings: 4 daily
Sample serving: 1/2 c fresh, frozen, canned fruit; 1/4 c dried fruit; 3/4 c juice
Low- or non-fat dairy
Servings: 2 daily
Sample serving: 1 c milk or yogurt; 1 1/2 oz cheese; 3 oz tofu
Lean meats, poultry, fish
Servings: 1 1/2 daily
Sample serving: 3 oz cooked
Fats, oils, dressings
Servings: 1 daily
Sample serving: 1 tsp oil or margarine; 1 T salad dressing
Nuts, seeds, beans
Servings: 1 or 2 a week
Sample serving: 1/2 c cooked beans; 1/3 c nuts; 2 T seeds
Servings: 3 a week
Sample serving: 1/2 c frozen yogurt