Bioflavonoids include several families of plant-based compounds with similar chemical structures. In some studies, a diet high in foods containing flavonoids has been linked to a reduced risk of cancer, heart disease and neurodegenerative disease. However, results are mixed and it is not yet clear whether supplements or purified flavonoid extracts have the same benefits as the foods themselves.
Fruits
Red, blue, and purple berries are high in several types of bioflavonoids, including anthocyanidins, catechins and flavonols. Citrus fruits and juices contain abundant amounts of flavonoids in the flavanone family, including herperetin. Apples are rich in proanthocyanidins and catechins. Most of the these compounds are concentrated just below the skin so eat the fruit with the peel to receive the full benefit. The flavonoid resveratrol, is found in the skin of red grapes and appears to protect against heart disease.
Soy and Legumes
Isoflavones are plant compounds that appear to mimic some biological activities of estrogen in the body. They are under investigation to determine whether they offer protection from cancers regulated by hormones, such as breast and prostate tumors. Isoflavones are found in soy products, legumes and flax seed. Interestingly, soy may have different health effects depending on how it is prepared. Nonfermented soy, such as soy milk or tofu, appears to protect against stomach cancer while fermented soy products, including miso and soy paste, appear to elevate the risk.
Vegetables
Broccoli and kale are rich in flavonoids from the flavonol family, including quercetin. These flavonoids are also commonly found in yellow onions and scallions. Parsley, thyme, celery, hot peppers, tomatoes and eggplant provide flavonoids in the flavone family, including the compounds apigenin and luteolin. Cruciferous vegetables, such as broccoli, cabbage, Brussel sprouts, kohlrabi, mustard greens, rutabaga, turnips and bok choy, contain mustard oils that are rich in isothiocyanates.
Tea
Teas are a major source of flavonoids in some populations. Green and white teas have high levels of catechins while black tea and oolong varieties are rich in theaflavins and thearubigins. Importantly, different brands and products may contain very different amounts of bioflavonoids. Consult the manufacturer for more detailed information on flavonoid content.
