What are flavonoids? Flavonoids are naturally found in plants giving them their unique colors. More recently they have been isolated and studied for their health benefits. Some of the more well-known flavonoids including epicatechin (found in green tea) and quercetin (found in onions) have been researched extensively. In total there are thousands of flavonoids found in plants with estimates reaching more than 5,000 different types of flavonoids.
Flavonoids are often associated with their ‘antioxidant properties but research is suggesting they may have a bigger role in promoting health. Pharmacological studies have begun to reveal specific mechanisms that can benefit those with heart disease, inflammation, detoxification, brain health and more.
A search of PubMed using the keyword ‘flavonoid’ will reveal more than 97,000 research articles. If you use the keywords ‘flavonoid AND inflammation’ more than 5,000 articles will be available to you.
Background on Flavonoids
Flavonoids are found in a variety of foods giving them their vibrant colors. Flavonoids are a large class of compounds that include anthocyanidins, flavanols, flavones, flavonols, flavonones, and isoflavones.
Flavones: Examples include luteolin and apigenin. Good sources of flavones are celery, parsley, various herbs and hot peppers.
Here are research articles about anthocyanidins.
Anthocyanidins: Examples include malvidin, pelargondin, peoidin and cyanidin. Good sources of anthocyanidins include red, purple and blue berries; pomegranates; plums; red wine; and red and purple grapes.
Flavonones: Examples include hesperetin, eriodictyol and naringenin and most commonly found in citrus fruits.
Isoflavones: Examples include genistein, glycitein and daidzein. Isoflavones are highly concentrated in soybeans, soy products, and legumes. Isoflavones are phytoestrogens and can act like the hormone estrogen.
Flavonols: Examples include quercetin and kaempferol and found in found in onions, leeks, Brussels sprouts, kale, broccoli, tea, berries, beans and apples. Quercetin is very popular for relieving allergies, hay fever and hives. Quercetin also has anti-inflammatory benefits. These powerful anti-inflammatory flavonols including Kaempferol and other flavonols have been suggested to reduce inflammation associated with chronic diseases.
Flavanols: The most common example is catechins which are found in tea, cocoa, grapes, apples, berries and red wine. There are three primary types of flavanols: monomers (more widely known as catechins), dimers and polymers. For example, green tea contains monomer called a catechin while black tea contains dimers of catechins (i.e. 2 catechins linked together).
Here are some research articles about the health benefits of tea.
Function of Flavonoids in Plants
Flavonoids help protect plants against ultraviolet (UV) damage, help one plant cell to send a signal to another plant cell, protect the plant against chemical damage, and protect the plant against bacteria and fungus infections.
Health Benefits of Flavonoids
Heart health
Flavanoids have antioxidant properties and have been suggested to protect LDL cholesterol particles from breaking down. The breakdown of LDL particles is associated with atherosclerosis. Flavonoids can help protect blood vessels. A study published in the American Journal of Clinical Nutrition analyzed flavonoid intake in 4,807 people. The results found that those who consumed higher levels catechins from tea had lower risk of heart attacks. The flavonoid intake of querecetin, kaempferol, and myricetin were significantly associated with lower risk of fatal heart attacks. (1)
Cocoa and chocolate not only taste good but also can provide flavonols. The flavonols found in ‘dark’ chocolate, not milk chocolate have been suggested by researchers to reduce inflammation in the arteries. A clinical trial published in the journal Vascular Pharmacology found high flavonol dark chocolate improves cardiovascular function.
Anti-inflammatory
Flavonoids have been linked in laboratory studies to reduce inflammation. One of the mechanism to reduce inflammation is to reduce the activity of cyclooxygenase, lipoxygenase, and cytokines. High activity of these enzymes are associate with inflammation and are an important target when attempting to reduce chronic inflammation. The mechanism of reducing inflammation would be different from aspirin or ibuprofen. In fact, recent studies have linked ibuprofen to heart failure.
Brain function
Flavonoids have long been associated with promoting heart health but more recent studies have suggested a benefit for improving memory and cognition. A possible mechanism includes the ‘direct action’ on cell signaling pathways including the MAP kinase (mitogen-activated protein kinase), ERK (extracellular signal-regulated kinase), and PI3k-Akt (phosphoinositide 3-kinase-Akt) signaling. An ‘indirect action’ could be the role of flavonoids in promoting normal blood flow, reducing platelet aggregation (i.e. sticky platelets), and improving blood pressure. (2)
Here are research articles about plant medicine for brain health.
Detoxification
Flavonoids can also help your body detoxify chemicals that get into your body. Human research has found that flavonoids can increase the activity of detoxification enzymes including glutathione-s-tranferase (GST), Nrf2, NQO1 and more. These enzymes will recognize a foreign chemical in your body and ‘tag’ it. Once the foreign chemical is tagged it can be quickly removed from your body in your stool or urine. (3)
References:
- Am J Clin Nutr. 2002 May;75(5):880-6.
- Front Nutr. 2017 May 16;4:19.
- 2013 Aug;95(8):1525-33.
His research on plant medicine has led to more than 45 publications and abstracts.This research has been presented at international meetings in the USA, France, Turkey, Peru, Israel, Austria, and Italy.
Categories: Antioxidant, Ask the Pharmacist, Cholesterol, Detoxification, Heart, Inflammation