Nitrate ingested in foods such as beetroot juice can considerably increase the amount of nitric oxide (NO) exhaled during respiration, researchers in Ireland reported — a finding of interest to cystic fibrosis (CF) patients, known to have low nitric oxide in their exhaled breath.
Nitric oxide plays important roles in protecting the airways against inflammation and infections, although the exact effect of low levels of exhaled NO on people is rather less certain. But it is also established that CF patients with higher levels of NO in their airways and NO metabolites in their sputum have better lung function, which suggests that increasing levels of nitric oxide may improve lung function in CF.
Previous efforts by scientists to increase levels of NO in CF patients, including inhaled NO, have shown inconsistent results.
In the study, “Dietary Nitrate Acutely and Markedly Increased Exhaled Nitric Oxide in a Cystic Fibrosis Case,” published in the journal Clinical Medicine and Research, Conor Kerley and colleagues at the Paediatric Respiratory Department at National Children’s Hospital in Dublin reported the case of a 12-year-old boy with CF who showed a marked increase in exhaled NO following dietary nitrate consumption.
“To our knowledge, this is the first report of dietary nitrate in [cystic fibrosis],” the authors said.
The researchers used a double-blind, randomized, placebo-controlled, crossover design to assess the acute impact of dietary nitrate on exhaled NO levels. Specifically, they gave the boy either 140 mL of beetroot juice, which is high in nitrate, or 140 mL of beetroot juice that had been depleted of nitrates. Neither the boy nor the researchers knew which drink contained nitrates, and which did not. They then measured the amount of NO the boy exhaled before and, again, 1.5 hours after he drank the juice.
Results showed a 150% increase in the amount of NO exhaled after the boy drank the normal beetroot juice, and a 17% decrease after drinking the juice depleted of nitrates. There was no difference in his lung function after either drink.
Researchers concluded that, although their work is limited to a single boy with mild CF, dietary nitrate is remarkably safe and can increase levels of NO to a greater extent than existing CF therapies.
“We suggest the dietary modification of [NO], including via vegetable consumption in [cystic fibrosis] is worthy of further exploration,” the team concluded.