Some of the most common flavonoid-rich foods are berries and green or black tea. There are five distinct subcategories of flavonoids. There are several fruits, vegetables, nuts and grains in each category that contain a high amount of each specific flavonoid.
The five subcategories of flavonoids are: flavonols, flavan-3-ols, flavones, flavonones and anthocyanins. In order to consume a diet rich in flavonoids, it is important to eat foods from each category. Onions, apples, romaine lettuce, tomatoes and almonds are some foods that are rich in flavonols. Flavan-3-ol foods include green or black tea, bananas, peaches and pears. Blueberries, strawberries, cranberries and raspberries are all rich in anthocyanins. Lemons, oranges and grapefruit have flavonones. The flavones group has a diverse range of plants including celery, chili peppers and watermelon.
Flavonoid-rich foods are susceptible to nutrient loss during cooking, as flavoniods are soluble in water. Boiling flavonoid-rich foods may result in a decrease in flavonoid content. Because flavonoids contribute to a plant's color, foods that dull during cooking may lose some of their nutrients. Flavonoid content also decreases over storage time. Fruits and vegetables have the highest nutrient content when they are fresh.
Many flavonoid-rich foods have the highest nutrient concentration in their skins or peels. Before consumption, rinse the plant or wash with a vegetable brush. Most of the flavonoid plant peels and skins are safe for consumption. Don't pre-peel, cut or slice the plant before storing. This compromises the exterior and contributes to flavonoid loss.