flavonoid

noun

fla·​vo·​noid ˈflā-və-ˌnȯid 

: any of a large group of typically biologically active water-soluble plant compounds (such as the anthocyanins and flavones) that include pigments ranging in color from yellow to red to blue and occur especially in fruits, vegetables, and herbs (such as grapes, citrus fruits, peppers, and dill)

Blueberries are packed with a flavonoid known as anthocyanin, an antioxidant proven to help boost the immune system …

—Margaret Darby

Flavonoids are effective scavengers of free radicals in the test tube (in vitro). However, even with very high flavonoid intakes, plasma and intracellular flavonoid concentrations in humans are likely to be 100 to 1000 times lower than concentrations of other antioxidants …

—Jane Higdon

The rich palette of dyes in butterflies' wings are all derived from chemicals called flavonoids, which the insects cannot make themselves and must sequester from their food plants.

—Nicholas Wade

see bioflavonoid

Examples of flavonoid in a Sentence

Recent Examples on the Web

Kash says they are packed with antioxidants such as polyphenols and flavonoids to neutralize free radicals that cause stress and inflammation and help with boosting your immune system overall. — Marie Bladt, Vogue, 11 Aug. 2026

In lab studies, specific plant chemicals called flavonoids have been shown to stimulate glucagon-like peptide-1 (GLP-1), a hormone that regulates digestion and blood sugar levels. — Brittany Lubeck, Verywell Health, 7 Aug. 2026

Chamomile contains natural plant compounds called flavonoids, including apigenin, which have antioxidant and anti-inflammatory effects. — Brianna Tobritzhofer, HEALTH, 3 Aug. 2026

Watch the next revision of the Dietary Guidelines for Americans and any American Heart Association or Alzheimer’s Association statements that name specific flavonoid sources by food, not nutrient class. — Samantha Agate, Fort Worth Star-Telegram, 22 July 2026

Word History

Etymology

flavone + -oid

First Known Use

1947, in the meaning defined above

Medical Definition

flavonoid

1 of 2 adjective

fla·​vo·​noid ˈflāv-ə-ˌnȯid  ˈflav- 

: of, relating to, or being a flavonoid

flavonoid

2 of 2 noun

: any of a large group of typically biologically active, water-soluble, plant compounds (such as the flavones) that include pigments ranging in color from yellow to red to blue and occur especially in fruits, vegetables, and herbs (such as grapes, citrus fruits, peppers, and dill)

Tea contains substances called catechins (tea flavonoids) that may protect against heart disease and even cancer.

—UC Berkeley Wellness Newsletter

Flavonoids are effective scavengers of free radicals in the test tube (in vitro). However, even with very high flavonoid intakes, plasma and intracellular flavonoid concentrations in humans are likely to be 100 to 1000 times lower than concentrations of other antioxidants …

—Jane Higdon, An Evidence-Based Approach to Dietary Phytochemicals

Note: Flavonoids are polyphenolic 15-carbon compounds with a basic structure consisting of two benzene rings joined by a chain of 3 carbons.

see bioflavonoid