Flavanols and Flavonols
Perhaps the most confusing of the flavanoids are the flavanols and flavonols. Sometimes you will even see the names are even used interchangeably, as if they were the same thing. Yet, these are two different substances, with chemically different structures, but names that are distressingly similar. Like other flavanoids, flavanols and flavonols are pigments found in plants.
Flavanols are the most abundant of the flavonoids. They are also called flavan-3-ols, because of an alcohol group on carbon 3 of one of the rings. They are also sometimes called catechins because catechins are the most abundant type of flavanol we have found. Other flavanols include epicatechin, epigallocatechin, theaflavin and proanthocyanadin. Good sources are teas, chocolate, berries, apples, grapes and red wine.
Flavanols are not attached to sugar molecules. Flavonols, on the other hand, come linked to a sugar molecule. They absorb large amounts of UV light, and are found in the skin and outer layers of plants. One of their functions is to act as a sunscreen for the plant. In turn, exposing fruits such as grapes and berries to more sunlight makes them produce more flavonols. Quercetin is the most common flavonol. Others are kaempferol, myricetin, rutin and azaleatin. Some high flavonol foods are berries, apples, apricots, yellow onions, broccoli, scallions, kale, cranberries and sweet cherries.
Flavonols and flavanols are most well known for their antioxidant properties. Because of their chemical structures these compounds are easily oxidized themselves, they so they take the damaging free radicals that would go to other cells, and basically neutralize them.
See the phytonutrient page for links to specific flavonols and flavanols.
The information on this page is not meant to be used in treatment of medical conditions. Please seek the advice of a physician about any medical condition or symptom. Those with medical conditions should consult a medical professional about the appropriateness of taking dietary supplements or diet therapy, and how these methods will interact with their medications.
Antioxidant Activities of Flavonoids
Linus Pauling Institute
For detailed information about the chemical structure, formula, and molecular weight of various phytonutrients, visit
The US Dept of Agriculture.
Phytochemicals also gives detailed information on specific phytochemicals.
Search for herbs at the Sloan Kettering Memorial Cancer Center website.