Tart cherry concentrate had no impact on gout flares over a 28-day period, based on data from 50 adult patients.

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Urate-lowering therapy is part of gout management, and previous studies have suggested that tart cherry concentrate lowers sodium urate within hours in healthy volunteers and to a nonsignificant extent over 120 days in patients with gout, but “the optimal dose of tart cherry concentrate for either a serum urate effect on or flare prevention is unknown,” wrote Lisa K. Stamp, MD, of the University of Otago, Christchurch, New Zealand, and colleagues.

In a study published in Rheumatology, the researchers randomized 50 adults with gout and baseline serum urate levels greater than 0.36 mmol/L (6 mg/dL) to receive one of four doses of tart cherry juice concentrate (7.5 mL, 15 mL, 22.5 mL, or 30 mL) or a placebo twice daily for 28 days. Half of the participants were taking allopurinol and half were not taking any urate-lowering therapy.

After 28 days, patients who received cherry juice showed no significant changes in serum urate regardless of whether they were also taking allopurinol. In addition, cherry juice at any dose had no significant effect on reducing the serum urate area under the curve and no apparent impact on measures including urine urate excretion, change in urinary anthocyanins, and frequency of gout flares, compared with placebo. However, the cherry juice was well tolerated, and 84% of the study participants said they would recommend it to a friend as a method of gout prevention.

The researchers collected blood samples at baseline, and at 1, 3, and 5 hours after consuming cherry juice, and on days 1, 3, 7, 14, 21, and 28. “If there is an effect of cherry concentrate on gout flares over a longer time period, it is not likely to be mediated by reduction in serum urate,” the researchers said.

Of 24 adverse events reported during the study, 18 occurred in patients taking cherry juice at all dosage levels, and one case of hyperglycemia was potentially related to cherry concentrate. No serious adverse events associated with tart cherry concentrate occurred during the study period.

The study findings were limited by several factors including the inability to blind the study because participants prepared their doses at home, and the lack of data on the exact contents of the cherry juice concentrate used in the study, the researchers noted. However, the results suggest that tart cherry concentrate has no effect on serum urate concentration or urinary urate excretion, which make it unlikely to be useful in reducing gout flares, they concluded.

The study was supported by the Health Research Council of New Zealand. The researchers had no financial conflicts to disclose.

SOURCE: Stamp LK et al. Rheumatology. 2019 Dec 31. doi: 10.1093/rheumatology/kez606.