Flavonoids are phytonutrients in plant-based food products that often contribute to the color of the foods. They provide antioxidant activity which may play a significant role in cardiovascular health and may help to prevent against diseases such as cancer caused by free-radical damage. They may also provide benefit in the prevention of other chronic conditions such as osteoporosis and diabetes. Certain plant-based food groups are known to be much higher in flavonoids than others including some fruits, vegetables, spices and grains.
Many of the berries are high in flavonoids, particularly red, blue and purple berries. Darker and riper berries tend to have higher flavonoid value and processing may reduce levels. Blueberries and cranberries are known to contain quantities of the flavonol group including quercetin and myricetin. Blackberries and black grapes are high in the flavonoids epicatechin and catechin while raspberries, cherries and red grapes may be high in anthocyanidins and cyanidin.
Fruits that grow on trees have been shown to be high in flavonoids. Bananas contain quantities of anthocyanidins including cyanidin and delphinidin. Citrus fruits including grapefruit, lemons, limes and oranges are high in the flavonone group of flavonoids including hesperetin, naringenin and eriodictyol. Members of the Rosaceae family of tree fruits including apples, pears, plums, peaches and apricots are known to be high in catechin and epicatechin and are best if consumed raw with the skin on.
Nuts and Beans
Some nuts and certain beans, in addition to being high in protein, are also high in flavonoids. Dark beans such as black and kidney beans tend to be higher in flavonoids from the anthycyanidins group including delphinidin, malvidin, petunidin and kaempferol while beans that are consumed in an immature form such as fava beans or pinto snap beans are rich in flavonols such as epicatechin and epigallocatechin. Walnuts and pecans are high in anthocyanidins while pistachios and cashews are high in the flavonols catechins. The king of all plant proteins is the soybean, which is high in catechins and a particular type of flavonoid, the isoflavone group including genistein and daidzein.
Most vegetables contain quantities of flavonoids, particularly green and red vegetables. Members of the nightshade family including peppers, tomatoes and eggplants are high in the flavonols, quercetin and the flavones luteolin. Onions, particularly red onions and green onions, are also high in quercetin. Green vegetables such as celery and artichokes are high in the flavones apigenin and luteolin, while vegetables such as snap beans, okra and broccoli are high in flavonols including quercetin, kaempferol and myricetin.
Some spices and flavoring agents are particularly high in certain types of flavonoids, and, while generally consumed in smaller quantities, may still offer some health benefits particularly if used while fresh. Dill is known to be high in the flavonols quercetin and isorhamnetin while parsley is high in apigenin along with isorhamnetin. Thyme is high in the flavones luteolin and capers though rarely used are very high in the flavonols kaempferol and quercetin. The best news for some people may be that chocolate is known to be very high in catechins, particularly if consumed in the dark variety.
Fruit juices made from raw, unprocessed fruit maintains many of the health benefits of the fruit, particularly if consumed in an unfiltered form, as do vegetable juices. Red wine carries many of the health benefits of grapes and grape juice including high levels of anthocyanidins and the flavonols quercetin and myricetin. Tea of all types including black, red and green varieties have been shown to be high in catechins such as epigallocatechin along with related flavonols such as thearubigin.