A quercetin containing supplement reduces in niacin-induced flush in humans

Coronary artery disease is associated with increased serum levels of cholesterol, triglycerides: and LDL, but low levels of HDL. The most potent agent capable of reversing this trend is the vitamin nicotinic acid (niacin). However, compliance even with extended-release preparations and addition of acetylsalicylic acid (ASA) is hampered by the development of a feeling of erythema and burning ("flush"), especially on the face. We recently showed that the natural flavonoids quercetin and luteolin can eliminate "flush", as well as inhibit both niacin-induced plasma prostaglandin D₂ (PGD₂) and serotonin increase in an animal model. We conducted a pilot clinical study in humans. Four normal male subjects received (a) 1 g immediate release niacin either alone or after (b) the dietary formulation (Algonot-plus®) containing 150 mg quereetin per capsule. Subjects completed a visual scale (1=no, 5=worst response) symptom assessment. Erythema and burning sensation scores were both 4.75±0.50 and lasted for 3.63±1.11 hours. After Algonot-plus® administration, both scores were reduced to 2.5±0.58 and lasted for only 1.68±0.70 hours. Quercetin also inhibited methylnicotinate-induced human mast cell PGD₂ release. These preliminary results suggest that quercetin could reduce niacin-induced "flush" in humans.