What are flavonoids?
Flavonoids are polyphenols found in plant foods. They are natural pigments, which give yellow, red or blue color to fruits and vegetables.
Flavonoids in Foods
Naturally occurring flavonoids (except catechins and proanthocyanidins) are connected to one or more sugar molecules–in this form they are called flavonoid glycosides; when they are not connected to sugars, they are called aglycones. For example, hesperidin is a glycoside (with sugar) and hesperitin is an aglycone (without sugar).
|FLAVONOID SUBCLASS||FLAVONOID||FOODS HIGH IN FLAVONOIDS|
|Anthocyanidins||Cyanidin, delphinidin, malvidin, pelargonidin, peonidin, petunidin||Red, blue, and purple berries; red and purple grapes; red wine|
|Flavanols||Catechin, epicatechin, epicatechin gallate, epigallocatechin, epigallocatechin gallate||Yod kratin (a Thai vegetable), green tea, white tea, chocolate, grapes, berries, apples|
|Theaflavins, thearubigins||Black tea, oolong tea|
|Proanthocyanidins or condensed tannins or flavolans or flavan-3-ols||Chocolate, apples, berries, red grapes, red wine, maritime pine bark, cinnamon, aronia (chokeberry), grape seeds|
|Flavanones||Hesperetin, naringenin, eriodictyol||Oranges, grapefruits, lemons and their juices|
|Flavonols||Quercetin, kaempferol, myricetin, isorhamnetin||Yellow onions, scallions, kale, broccoli, apples, berries, Ginkgo biloba, teas|
|Flavones||Apigenin, luteolin, nobiletin, sinensetin, tageretin||Parsley, thyme, celery, hot peppers|
|Isoflavones||Daidzein, genistein, glycitein||Soybeans, soy products, legumes|
Flavonoids Health Benefits
There is INSUFFICIENT EVIDENCE about the effectiveness of high flavonoid intake from foods on the prevention or treatment of colorectal cancer or as antioxidants [1,3].
According to one 2002 cohort study in Finland :
- High quercetin intake (mainly from apples and onions) was associated with lower asthma incidence and lower mortality from ischemic heart disease in general population, and in lower incidence of lung cancer in men.
- High hesperitin intake (mainly from citrus fruits) was associated with lower incidence of asthma, cerebrovascular disease.
NOTE: The study results do not mean that quercetin or hesperitin actually prevent any disease.
In various studies, green tea polyphenols, catechins, and genistein supplements were associated with better protection against sun .