Quercetin lowers plasma uric acid in pre-hyperuricaemic males: a randomised, double-blinded, placebo-controlled, cross-over trial.
Level 2 - randomized trial
Individual randomized, double-blinded, placebo-controlled crossover trial
PubMed 26785820 · doi:10.1017/S0007114515005310
What was done
A randomised, double-blinded, placebo-controlled, cross-over trial evaluated 22 healthy males aged 19-60 years with baseline plasma uric acid in the higher-normal range (mean 339 [SD 51] µmol/l). Participants received 500 mg oral quercetin daily for 4 weeks versus placebo, separated by a 4-week washout period. The primary outcome was change in plasma uric acid concentrations at 2 and 4 weeks; secondary outcomes were changes in fasting plasma glucose, resting blood pressure, and 24-h urinary excretion of uric acid.
What was found
Quercetin significantly lowered plasma uric acid concentrations by -26.5 µmol/l (95% CI, -7.6 to -45.5; P=0.008) compared with placebo. No significant effects were observed on fasting glucose, resting blood pressure, or 24-h urinary uric acid excretion.
Why it matters
The study shows that a nutritional dose of quercetin can reduce circulating uric acid in humans, providing clinical support for its known in vitro inhibition of xanthine oxidoreductase.
Limits
The sample size was small (22 participants) and restricted entirely to healthy adult males with high-normal uric acid levels, limiting generalizability to females and individuals with clinical hyperuricemia or gout. The intervention duration was short (4 weeks), and long-term clinical outcomes were not measured.
Cited by
- supports Flavonoids like quercetin and luteolin inhibit the enzyme xanthine oxidase and reduce uric acid production.