New DASH Diet Improves Heart Health
Federal health experts kick off the new year with words of wisdom about healthy diet and reduction of long-term cardiovascular health risk.
Findings for the use of the Dietary Approaches to Stop Hypertension (DASH) diet were reported at a meeting of the American Heart Association and in the Journal of the American Medical Association (JAMA).
Two carbohydrate-reduced versions of the government's DASH diet have a beneficial effect on blood pressure, cholesterol levels, and long-term cardiovascular risk, researchers report.
The new diet shifts about 10 percent of calories from carbohydrates to either protein-rich foods or to monounsaturated fats such as olive or canola oil.
"This diet should be a frontrunner," says Dr. Frank Sacks, one of the authors of the study and a professor of medicine and nutrition at Brigham and Women's Hospital and Harvard in Boston.
"It improved the whole cardiovascular risk spectrum," notes Dr. Sacks. "A lot of patients are tough to control with the medications we have. Patients might not even need drugs if they go on the diet."
"This is a modified version of the old diet," Dr. Sacks explains. "The DASH diet was a real breakthrough for lowering blood pressure and we changed it. We reduced the carbohydrate content and replaced it with unsaturated fat or protein, and it lowered blood pressure more and improved lipids, and overall cardiovascular risk goes down."
He calls the new regimens "an improvement over something that's already good."
Another expert agreed that the two new versions of the DASH diet, as well as the original DASH, which was developed by the National Heart, Lung, and Blood Institute (NHLBI), should work.
"These are just alternative versions," says Dr. Jay Skyler, a professor of medicine and associate director of the diabetes research institute at the University of Miami School of Medicine.
"To me, whether you get a little bit more lowering with one or another diet than the other matters less than the fact that you ought to stick to any one of these three," he comments. "They're all better than the conventional diet that these people were on."
The DASH diet has been considered the gold standard of heart-healthy nutrition since it was pioneered in the mid-1990s.
The original diet was carbohydrate-rich, emphasizing fruits, vegetables, and low-fat dairy products.
Unfortunately, in addition to lowering "bad" or low-density lipoprotein (LDL) cholesterol, the regimen also reduced "good" or high-density lipoprotein (HDL) cholesterol, and had no effect on blood fats called triglycerides.
To help make the regimen even healthier, the same researchers updated the diet and compared the two new versions with the old one.
For this study, 164 adults aged 30 and older with elevated blood pressure were assigned to one of three diets: one in which carbohydrates represented 55 percent of calories (close to the original DASH diet); one that shifted 10 percent of carbohydrate calories to protein (about two-thirds from plant sources and the rest from chicken and egg whites); and one that shifted 10 percent of calories to unsaturated fat, mostly olive or canola oils.
About half of the participants were African American, a group at especially high risk of developing hypertension.
All of the diets lowered participants' blood pressure, LDL cholesterol, and estimated coronary heart disease risk, the researchers report, and the protein and unsaturated fat diets showed even better improvements.
Compared to the old diet, the enhanced-protein version decreased blood pressure by an extra 1.4 millimeters of mercury (mm Hg) overall and by an extra 3.5 mm Hg among those with hypertension; it decreased LDL cholesterol by an additional 3.3 milligrams per deciliter (mg/dL) and triglycerides by 15.7 mg/dL.
Compared to the original DASH diet, the unsaturated fat-rich version decreased systolic blood pressure by an additional 1.3 mm Hg overall and by 2.9 mm Hg among those with hypertension; it increased HDL cholesterol by an extra 1.1 mg/dL and lowered triglycerides by 9.6 mg/dL.
Both the protein and unsaturated fat diets reduced heart disease risk more than the DASH diet.
Breakfast was similar in all three diets and included fresh fruit, fruit juice, whole grain cereal, and skim milk. Lunches and dinners were varied. A typical protein-diet dinner might include one ounce of raisins and cherries, where the carbohydrate dinner included a peppermint patty.
How practical are the improvements? All the study participants were given their meals. In the real world, people will have to prepare these meals themselves.
"Would people be able to stick to any of these as effectively when they're doing it at home? That's the unknown thing here," Dr. Skyler says. "I think whatever people will stick to and are happy with will work. I would be happy with the results of any of these three."
Dr. Sacks says his team was working on making the diet easy to use.
"Our next project is to work on foods and menus and things that people can use, to give people more specific guidance," he remarks. "Hopefully that'll be out in a couple or three months. We feel a sense of urgency to get some real practical stuff out like we did with the DASH diet."
An accompanying editorial also emphasizes the need for lifestyle changes such as more exercise, in addition to diet, to keep blood pressure low.
Always consult your physician for more information.
Difficulty breathing, called dyspnea, is considered a risk factor that could signal heart trouble, according to a study reported in the New England Journal of Medicine.
A study of nearly 18,000 people who had standard stress tests found that those with dyspnea but no other signs of heart problems were at more than twice the risk of death from cardiac causes (or any other reason) than those with angina, the chest pain that is typically regarded by physicians as a significant sign of risk.
The lesson for people when they visit a physician is to be sure to mention any shortness of breath, says senior researcher Dr. Daniel S. Berman, director of cardiac imaging at Cedars-Sinai Medical Center in Los Angeles.
"The patient often doesn't think of it as a symptom," notes Dr. Berman. But when signs of a heart problem are discovered, "and we ask whether there is shortness of breath, they say 'yes.'"
Dyspnea has many causes, and physicians routinely ask people if they have trouble breathing, says Dr. Alan Rozanski, director of nuclear cardiology at St. Luke's-Roosevelt Hospital in New York City, and another member of the research team.
He says trouble breathing is often a tip-off to the physician that a patient may have some underlying lung disease, maybe even heart failure.
But until now, only a few studies, most with a limited number of participants, have looked at whether dyspnea is a predictor of cardiac events, Dr. Rozanski says.
The New York team divided their 17,991 patients into five groups based on the number and type of symptoms: no symptoms, two different forms of angina, chest pain not caused by angina, and dyspnea alone.
After an average follow-up of nearly three years, the death rate among patients with dyspnea was significantly higher than for those with any other symptom or no symptoms - even in patients with no known history of coronary artery disease.
The risk of sudden death was also four times higher for patients with dyspnea and coronary artery disease than for people with no symptoms, the researchers note.
The bottom line: "People who have developed shortness of breath without any obvious lung problem should consider whether it is of cardiac origin," says Dr. Berman.
"For years, cardiologists have focused on chest pain as the primary symptom," he says. "They consider a variety of other factors as well, including depression, lack of sleep, and fatigue. This study increases interest in looking at other factors."
"We should think of shortness of breath not only in terms of lung disease," Dr. Rozanski adds. "We might need to screen a little more deeply for coronary artery disease. Someone with dyspnea might have a heightened need to undergo stress testing or other screening."
Dr. Rozanski says the study is already affecting decisions on stress testing in his practice. Now, when evaluating the need for an individual to have the test, he includes such factors as age, chest pain, and gender (men are more likely to be referred for the test).
But Dr. Rozanski adds there is "one important caveat."
"This study was done in a population of middle- to upper-class white individuals," he says. "We know that cardiac risk can vary by gender, ethnicity and other factors. To see whether dyspnea is as predictive in African-Americans or Hispanics, another population study has to be done."
Always consult your physician for a diagnosis.
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American College of Cardiology
American Heart Association
Centers for Disease Control and Prevention (CDC)
Journal of the American Medical Association
National Heart, Lung, and Blood Institute (NHLBI)
National Institutes of Health (NIH)
National Library of Medicine
National Women's Health Information Center
New England Journal of Medicine
NHLBI DASH Eating Plan
US Health and Human Services