January 09, 2015NEW YORK (Reuters Health) – Inorganic nitrate administration via beetroot juice improves exercise capacity in patients with heart failure and preserved ejection fraction (HFpEF), according to findings from a single-dose study.
The inorganic nitrate “increased exercise capacity in patients with HFpEF by targeting peripheral abnormalities, specifically, enhancing the vasodilatory response during exercise (with a consequent increase in the cardiac output during exercise) and reducing the late systolic load of the left ventricle, which has deleterious consequences on the LV,” Dr. Julio A. Chirinos, a cardiologist at the University of Pennsylvania Perelman School of Medicine in Philadelphia, told Reuters Health by email.
“These findings,” he continued, “have implications for our understanding of the disease and probably for its treatment. In particular, it provides proof of concept that inorganic nitrate may represent a viable therapeutic approach for HFpEF. However, this remains to be tested in larger trials with sustained (chronic) administration, which we hope to accomplish in the new few years.”
As reported December 22 online in Circulation, Dr. Chirinos and colleagues conducted a randomized, double-blind, crossover study with 17 subjects.
Following a single dose of beetroot juice or nitrate-depleted placebo, the subjects performed supine-cycle, maximal-effort cardiopulmonary exercise tests.
Supplementation increased median plasma NO-metabolites from 10 to 326 micromoles (p=0.003). Peak oxygen volume was also significantly increased (12.6 versus 11.6 micromoles p=0.005) as was total work performed (55.6 vs 49.2 kilojoules, p=0.04). There was, however, no change in efficiency.
Supplementation also increased exercise vasodilatory and cardiac output reserves and reduced arterial wave reflections, which are linked to left ventricular diastolic dysfunction and remodeling, the investigators said.
Commenting by email, Dr. Mark T. Gladwin, co-author of an editorial, told Reuters Health that “Nitrate and nitrite have historically been considered toxic elements of our diet but over the last decade it has become clear that they are metabolized to form nitric oxide, a very important vasodilator, that regulates cardiovascular functions, like blood pressure and blood flow.”
“Nitrate that is present in food like beets,” continued Dr. Gladwin, “is converted by bacteria in our mouths to form nitrite and then nitrite is then absorbed into the blood and converted in our bodies to nitric oxide.”
“The current study,” he added, “addresses a major challenge in medicine, the treatment of heart failure with preserved ejection fraction. This type of heart failure is common with increasing age and is often associated with high blood pressure, exercise intolerance and diabetes. There are currently no therapies for this very common form of heart failure. In the present study, a single drink of beet root juice with nitrate, increased exercise duration by one minute and improved blood flow to skeletal muscles, suggesting a potential role in treating this condition.”
“However,” concluded Dr. Gladwin of the University of Pittsburgh in Pennsylvania, “More studies are needed with longer courses of therapy before we should all start drinking beetroot juice.”
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