A recent study entitled “Dietary nitrate supplementation improves exercise performance and decreases blood pressure in COPD patients” suggests that supplementing nitrate in COPD patients’ diets may increase their exercise capacity while reducing blood pressure. The study was published in the journal Nitric Oxide: Biology and Chemistry.
Several studies have focused on the link between diet and exercise capacity. Recently, the role of dietary nitrate, which can be found in abundance in the green leaves of vegetables and beetroots, was shown to improve the exercise capacity of healthy individuals by being converted into nitric oxide (NO) — an important regulator of a wide range of physiological processes, including blood circulation, metabolism and immune functions.
Chronic obstructive pulmonary disease (COPD) is a progressive lung disease characterized by chronically poor airflow, with patients exhibiting symptoms of shortness of breath and cough. Thus, daily activity, such as climbing steps and exercise, is severely impaired in COPD patients, leading to a conditioned, sedentary life-style which further diminishes patients fitness and exacerbates the deterioration of their physical functions.
A team of researchers at Wake Forest University sought to determine whether supplementing the diet of a small group of COPD patients with acute beetroot juice ingestion improved their physical capacity. The authors studied fifteen patients with mild or moderate COPD – 12 males and three females — who were randomly assigned to receive either one of two treatments — beetroot juice followed by placebo or the reverse, placebo and then beetroot juice. The team measured as primary outcome patients’ sub maximal exercise work capacity (determined by patients exercising on a bicycle at 75 percent of their previously established maximum work rate); additionally, their secondary outcomes included determining nitrate and nitrite plasma levels and blood pressure; heart rate and oxygen consumption; and finally dynamic hyperinflation (exercise-induced air trapping, a phenomenon COPD patients are particularly susceptible to), dyspnea (shortness of breath) and discomfort to the legs.
The authors found that acute ingestion of beetroot juice increased ingestion of nitrate, when compared to the placebo drink (prune juice, since it lacks nitrates) resulting in a highly significant increase of plasma nitrate and nitrite levels, extended patients exercise capacity, while reducing patients blood pressure. Nitrate supplementing did not alter patients other secondary parameters, such as heart rate, inspiratory capacity nor dyspnea and leg discomfort. The authors concluded their study is the first showing that dietary nitrate supplementation significantly improves older COPD patients exercise capacity and blood pressure. However, the authors recognized limitations to their study and the necessity for further studies to confirm and extend the benefits of nitrate supplementation to COPD patients.
Michael Berry, study leading author and chair of Wake Forest’s department of health and exercise science noted, “The intent of this study was to determine if acute ingestion of beetroot juice, which is rich with nitrates, prior to exercising could improve the exercise capacity of COPD patients. One of the benefits of exercise is that if you get positive results, you’re more likely to continue doing it. If beetroot juice positively impacts those results, it could motivate COPD patients to continue to be physically active and improve their health.”