Tart cherry juice has no acute effects on uric acid, vascular function and inflammation: A randomised crossover trial

Background: Hyperuricaemia increases the risk of gout, and cardiovascular disease, thus dietary modifications that reduce urate are of interest. Cherries have been reported to lower urate, but studies examining acute effects have mostly failed to include a control group, despite urate being known to exhibit diurnal fluctuations, typically falling throughout the day. Aim: This study aimed to determine the acute effects of a single serving of tart cherry juice on uric acid metabolism and risk factors for cardiovascular disease relative to a control drink. Methods: In an open-label, randomised, controlled, crossover design, 12 healthy adults (mean age 41.1 (±11.1) y; mean body mass index 26.4 (±4.3) kg/m²; 7 men and 5 women) consumed 250 mL tart cherry juice (containing 30 mL of concentrate) and 250 mL water (control) on separate occasions ≥7 days apart. Serum uric acid, central and brachial blood pressure, augmentation index and pulse wave velocity were measured at baseline, 1, 2, 3, 5 and 24 h, post-drink, serum C-reactive protein at baseline, 2 and 5 h, and creatinine-adjusted urinary uric acid at 0 to 2, 2 to 4 and 4 to 5 h. Results: There were no statistically significant main effects of drink type or drink by time interactions (all outcomes p > 0.05). However, independent of drink type, serum uric acid (p = 0.008), urinary uric acid (p < 0.001), C-reactive protein (p = 0.023) and measures of blood pressure (all p < 0.05) changed with different temporal patterns throughout the day (main effects of time, p < 0.05). Conclusion: These results indicate that diurnal fluctuations may partly explain the beneficial acute effects of cherry consumption on uric acid metabolism and inflammation previously reported in studies without a comparator control group.