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Background Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease characterised by breathlessness and reduced exercise capacity. Dietary nitrate (NO 3 −) supplementation, in the form of beetroot juice (BRJ), increases nitric oxide (NO) bioavailability, which may enhance vascular function and oxygen delivery. This study investigated the acute effects of nitrate-rich BRJ (NR-BRJ) supplementation on exercise performance in individuals with confirmed IPF.Methods Patients with IPF who required ambulatory oxygen or demonstrating exercise-induced desaturation were enrolled in a randomized, double-blind, placebo-controlled crossover study. Each participant completed screening followed by two interventional visits. Participants received 140 mls nitrate-rich beetroot juice (NR-BRJ) on one occasion and nitrate-depleted placebo beetroot juice (Plc-BRJ) at the other, with a 7–30 day washout period. Primary endpoint was the Endurance Shuttle Walking Time (ESWT). Endothelial function was assessed using flow-mediated dilatation (FMD). Data normality was assessed with the Shapiro-Wilk test. Paired t-tests and Wilcoxon signed-rank tests were applied as appropriate.Results The cohort included 20 patients with IPF (mean age: 70.3 ± 11.3 years; 75% male). Mean FVC was 3.21 ± 0.75 L (88% ±16.3% predicted) and TLco 48.6 ± 7.9% predicted. ESWT performance improved by median difference of 31 s (IQR: –9.5 to 100.0; p = 0.043); with small to moderate effect (d = 0.44). Median [IQR] values were 373 s [291.3–619.8] for NR-BRJ and 370.5 s [276.0–527.5] for Plc-BRJ. A statistically significant increase in endothelial function, as measured by FMD, was observed 180 minutes post-consumption (NR-BRJ: +2.97 ± 5.46%; Plc-BRJ: –0.71 ± 4.72%; p = 0.043).Abstract P30 Figure 1Conclusion These findings suggest benefit from acute dietary nitrate supplementation with NR-BRJ in IPF patients with hypoxia on exercise and vascular function, consistent with previous findings in COPD and pulmonary hypertension. Longer term studies are needed to see if this translates into sustained clinical benefit.