The flavonoid rutin is a flavonol glycoside comprised of the flavonol quercetin and the disaccharide rutinose. Rutin is found in many plants, especially the buckwheat. Other rich dietary sources of rutin include black tea and apple peels.

Rutin is considered to be an important nutritional supplement because of its ability to strengthen capillaries, whereby helping people suffering from arteriosclerosis (the hardening of the arteries) or high blood pressure. Rutin belongs to a group of plant compounds called bioflavonoids that also include the important catechins of green tea and the polyphenols of red wine. Recent studies have shown that the bioflavonoids are powerful antioxidants that fight free radicals. Free radicals are said to be responsible for as much as 90 percent of all the human diseases such as cancer, arteriosclerosis, strokes, senility due to aging, etc.

Typical doses used are 500 mg once or twice daily. Those with venous insufficiency/varicose veins often use 500 mg taken twice daily.