Do Polyphenolic Supplements Help Allergic Rhinitis?

Polyphenolic compounds found in foods such as apples, berries, grapes, onions, tea, and coffee have been shown to reduce mediators of allergic reactions (e.g., eosinophils and proinflammatory cytokines), but data regarding symptoms of allergic rhinitis are inconclusive. To gather more evidence, researchers in Japan performed a systematic review and meta-analysis, including 13 randomized, placebo-controlled trials of oral polyphenolic supplements (flavonoids in 10 trials, nonflavonoids in 3) in 800 patients with allergic rhinitis (perennial in 500, seasonal in 300).