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March 1, 2000 (Minneapolis) -- In a new study, researchers say that people with heart failure might benefit from a combination of exercise and the dietary supplement arginine to improve blood flow to the heart and the rest of the body. But other heart experts warn that the findings are inconclusive.
Other recent research has shown that heart failure may be a disorder that affects the entire body, rather than just a problem with the heart. Earlier studies have shown, for example, that people with heart failure have alterations in muscle metabolism that contribute to their inability to exercise.
Although earlier studies have shown that an enlargement of blood vessels, allowing increased blood flow, resulted with just exercise and with arginine alone, the authors of a study published in today's issue of the Journal of the American College of Cardiology wanted to determine if a combination of both might lead to greater benefits.
The preliminary trial involved 40 men 70 years or younger, all with heart failure. Each did handgrip exercises six times a week and/or took the supplement L-arginine three times a day. The researchers found that the combination of regular exercise and the over-the-counter dietary supplement led to a greater enlargement of blood vessels than either therapy alone.
Rainer Hambrecht, MD, an author of the study, says that exercise and arginine together seem to significantly improve the ability of the blood vessels to supply oxygen and nutrients to the cells of the body, including the heart. Hambrecht is with the University of Leipzig Heart Center in Germany.
Heart specialists who spoke with WebMD were unanimous in their opinion that the results are inconclusive and were quick to point out the study's limitations.
" trials with as many as 500 patients have shown opposite results," Andrew L. Smith, MD, tells WebMD. "It would be a huge leap to suggest that there are implications [for the patient] from a trial of 40 people." Smith is assistant professor of medicine in the Division of Cardiology and medical director for the Congestive Heart Failure Program at Emory University School of Medicine in Atlanta.
"There are weaknesses in this study," Steven Almany, MD, tells WebMD. He points out that the study participants were healthier than those doctors usually see, and that the researchers looked only at arm exercises. "Does that mean that exercising the leg or heart should show similar responses? We just don't know that," he says. Almany, medical director in the department of cardiology at William Beaumont Hospital in Royal Oak, Mich., was not involved in the study.
Smith says that though the new data are interesting, larger-scale trials are needed. "While is a natural substance, we know that certain natural substances can be harmful," he says. "There is a concern in the heart failure community that patients are taking [over-the-counter] medications that may have harmful effects."
But Almany has no problem giving arginine to his patients. "Right now, if a patient asked me about taking arginine, I would have no with it," he says. Still, he adds, "This is not a definitive study, and we need to take it further. One thing we do know is that exercise is beneficial for people with heart failure. That's been proven."
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