The phytonutrients known as flavonoids are well known for their protective effects against cancer, decrease of inflammation, prevention of mutations and control over vital cellular enzyme activities.1 Plants, fruits, vegetables, grains, flowers and other natural or isolated substances contain these chemicals. A more thorough explanation of flavonoids and flavonols, their dietary sources and their potential health advantages will be discussed in this article.
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The phytonutrients known as flavonoids are well known for their protective effects against cancer, decrease of inflammation, prevention of mutations and control over vital cellular enzyme activities.1 Plants, fruits, vegetables, grains, flowers and other natural or isolated substances contain these chemicals. A more thorough explanation of flavonoids and flavonols, their dietary sources and their potential health advantages will be discussed in this article.
There are several types of flavonoids found within a diversity of plant categories. The largest category is flavonols found in kale, lettuce, tomatoes, apples, grapes, berries, garlic and onions. Other categories are:
- Flavones: parsley, celery, thyme, green olives;
- Flavanones: citrus fruit;
- Isoflavones: soybeans and legumes;
- Anthocyanins: cranberry, blackberry, red grapes and strawberries.1
Flavonoids are the natural substances that defend plants from many ecosystem challenges. They provide a unique ultraviolet filter and serve as signaling molecules, detoxifying agents and antimicrobial defense compounds. One study found that flavonoids are the components that protect plants against cold and drought, and may play a functional role in heat acclimation and freezing tolerance.2
Discovering Flavonols
Of all the flavonoid subgroups, flavonols are the largest, with more than 6,000 types.1 Many fruits and vegetables contain flavonols, including kale, lettuce, tomatoes, apples, grapes, berries, onions, garlic and scallions.
Found in the pigments of plants, quercetin is the most studied species of flavonols and can also be found in cocoa, green tea, red wine, bananas, peaches and pears. Quercetin is a strong antioxidant and is used as an additional treatment for Alzheimer’s disease as an anti-inflammatory agent.3, 4
A study by Weng suggested that quercetin works as an immune regulatory agent within the body through basophils and mast cells (immune-response cells) as a stabilizer and prevents pro-inflammatory and allergy-causing mediators. Immune cells are present during allergic reactions, autoimmune diseases and inflammatory diseases. The study found that quercetin and other flavonols can also block inflammatory cells that develop into other skin conditions or diseases.3
Related: Flavonoids From Tea Improve Well-Being of Older Clients
Flavonoids & Health
Flavonoids have been recognized as an essential component in a wide range of nutraceutical, pharmacological, therapeutic and cosmetic applications. This is due to their antioxidant, anti-inflammatory, anti-mutagenic and anti-carcinogenic capabilities, as well as their ability to alter essential cellular enzyme performances.1
They have been traditionally known to be created in specific places in plants and are responsible for the color and perfume of flowers. Flavonoids are present in fruits to attract pollinators to help in seed and spore germination, as well as the growth and development of seedlings.
Research has revealed that some flavonoids can provide health benefits including enhanced circulation, reduced inflammation in blood vessels and lowered blood pressure. These benefits may eventually reduce the risk of heart disease and stroke. Additionally, flavonoids have been discovered to increase cognitive performance by increasing blood flow to the brain and guarding against neurodegenerative illnesses.3
Chromophores are the skin's ultraviolet (UV) absorbing molecules, which include melanin, urocanic acid, amino acids and nucleic acids. Researchers have found that flavonoids applied topically may shield the skin by absorbing UV rays, preventing penetration and any negative effects that may follow.5 Topical application of certain flavonoids may provide sunscreen-like protection to the skin by absorbing UV radiation before it interacts with and harms topical cells (corneocytes) and eventually the skin.5, 6, 7
An increasing number of studies indicate that including foods or supplements high in flavonoids in your diet can improve your general health and well-being. For example, a study indicated that people who consumed diets rich in foods high in flavonoids, like berries, dark chocolate and green tea, had lower incidences of cardiovascular disease than people with diets low in flavonoids.8
References:
- Panche AN, Diwan AD, Chandra SR. Flavonoids: an overview. J Nutr Sci. 2016 Dec 29;5:e47. doi: 10.1017/jns.2016.41. PMID: 28620474; PMCID: PMC54658 Flavonoids
- Samanta, A, Das, G & Das, S (2011) Roles of flavonoids in plants. Int J Pharm Sci Tech 6, 12–35.Google ScholarHeal
- Weng Z, Zhang B, Asadi S, Sismanopoulos N, Butcher A, Fu X, Katsarou-Katsari A, Antoniou C, Theoharides TC. Quercetin is more effective than cromolyn in blocking human mast cell cytokine release and inhibits contact dermatitis and photosensitivity in humans. PLoS One. 2012;7(3):e33805. doi: 10.1371/journal.pone.0033805. Epub 2012 Mar 28. PMID: 22470478; PMCID: PMC3314669.
- Deepika, Maurya PK. Health Benefits of Quercetin in Age-Related Diseases. Molecules. 2022; 27(8):2498. https://doi.org/10.3390/molecules27082498
- Sime S, Reeve VE. Protection from inflammation, immunosuppression and carcinogenesis induced by UV radiation in mice by topical Pycnogenol. Photochem Photobiol. 2004;79(2):193-198.
- Rahul, Siddique YH. Neurodegenerative Diseases and Flavonoids: Special Reference to Kaempferol. CNS Neurol Disord Drug Targets. 2021;20(4):327-342. doi: 10.2174/1871527320666210129122033. PMID: 33511932.
- Hruza LL) , Pentland AP. Mechanisms of UV-induced inflammation. J Invest Dermatol. 1993;100(1):35S-41S. Chiu AE, Chan JL, Kern DG, Kohler S, Rehmus WE, Kimball AB. Double-blinded, placebo-controlled trial of green tea extracts in the clinical and histologic appearance of photoaging skin. Dermatol Surg. 2005 Jul;31(7 Pt 2):855-60; discussion 860. doi: 10.1111/j.1524-4725.2005.31731. PMID: 16029678.
- Mahmoud) AM, Hernández Bautista RJ, Sandhu MA, Hussein OE. Beneficial Effects of Citrus Flavonoids on Cardiovascular and Metabolic Health. Oxid Med Cell Longev. 2019 Mar 10;2019:5484138. doi: 10.1155/2019/5484138. PMID: 30962863; PMCID: PMC6431442.
Susan Wade, M.Ed., LE, has more than 30 years of experience in education, kinesiology, athletic training, nutrition and aesthetics. Her functional medicine business dives deeper into resolving health issues, connecting the gut, stress, skin and inside health to help others regain their own health.
