Flavonoids: Antioxidants Help the Mind
Naturally occurring plant pigments, flavonoids are one of the reasons fruits and vegetables are so good for you. Among the many benefits attributed to flavonoids are reduced risk of cancer, heart disease, asthma, and stroke.
By July 8, 2003 - last reviewed on June 9, 2016published
You probably know about the powerful antioxidant properties of vitamins C, and E, and beta carotene. But there's another group of antioxidants receiving a lot of attention; their names are less pronounceable, but their health benefits are at least as powerful.
Quercitin, kaempferol, and epigallocatechin might never become household words, but they are already household ingredients. They are just three among over 4,000 compounds classified as flavonoids. Naturally occurring plant pigments, flavonoids are one of the reasons fruits and vegetables are so good for you. Among the many benefits attributed to flavonoids are reduced risk of cancer, heart disease, asthma, and stroke. They may play a special role in protecting the brain.
Flavonoids, like other antioxidants, do their work in the body by corralling cell-damaging free radicals and metallic ions. But flavonoids go beyond the yeoman work of your average antioxidant. Scientists have found that certain flavonoids have antihistamine, antimicrobial, memory- and even mood-enhancing properties.
Food scientist Alyson Mitchell, Ph.D., who studies flavonoids at UC Davis, is optimistic about the salutary power of these compounds: "The current hope of scientists is to discover exactly what flavonoids should be eaten in what amounts to fight specific diseases."
Scientists already have some proof that antioxidants protect against and even reverse the cognitive declines seen from aging. The brain is especially subject to attack from free radicals of oxygen, as it is extremely metabolically active and the body's largest consumer of oxygen. Yet, it is deficient in free radicals to start with. Cumulative damage from free radicals occurs across the board but is especially implicated in memory decline, slowing of body movements and the fatigue, irritability, and mood disturbance that mark depression.
Flavonoids are present in myriad fruits and veggies, common and uncommon, but some sources are better than others. In general, the more deeply-hued the plant, the more flavonoids it provides. Fortunately, you don't have to eat brussels sprouts (they have a low flavonoid content) to get your flavonoid fix. Some potent flavonoid sources may even be on your favorite foods list. Good sources of various flavonoids include:
Quercetin is the flavonoid that enables apples to keep the doctor away. Quercetin has been shown to reduce cancer risk, prevent heart attacks, stave off cataracts, control asthma, prevent recurrent gout attacks, and speed healing from acid reflux.
Green tea contains, among others, the cancer-fighting flavonoid epigallocatechin gallate (ECGC). ECGC is unique in that it seems to battle cancer at all stages, from thwarting chemical carcinogens, to suppressing the spread of tumors. ECGC is as much as 100 times more powerful an antioxidant as vitamin C, and 25 times more powerful than vitamin E. ECGC also may account for the antibacterial properties of green tea.
Chocolate contains many of the same flavonoids found in tea. The darker the chocolate, the more flavonoids present. Cocoa powder is the richest source by weight, and to maximize your benefits, make your hot chocolate from scratch. Homemade hot chocolate will provide you with more flavonoids than a store-bought mix.
Flavonoids are the source of the well-known "French Paradox"—the ability of the French to consume lots of fat-laden cheese without dropping like flies from heart attacks. The red wine they enjoy is flavonoid-rich, which lowers their risk of heart disease. And if you're not a drinker, you can get almost all the same benefits from purple grape juice.
The pomegranate carries with it the mystique of ancient myth, but we moderns are beginning to realize that its health benefits are very real: pomegranate juice may have almost three times the antioxidant potency of an equal volume of green tea or red wine.
Delicious, relaxing chamomile tea is home to the flavonoid called apigenin, one of a handful of flavonoids recently found to have mood-enhancing properties. Currently the focus of intense study, they are thought to act on the same parts of the brain as common anti-anxiety drugs. In fact, certain synthetic flavonoids have been shown to have anxiolytic properties superior to diazepam. Research is in its infancy, however. For now, take your apigenin with sugar and lemon.
While many health benefits of flavonoids are not in dispute, there are a couple caveats to consider before sitting down to fill your face with flavonoids.
First, scientists are only now beginning to understand the effects of flavonoids in the body. As natural but real chemicals, flavonoids can interact with prescription drugs in a harmful way. The flavonoid naringenin found in grapefruit, for example, can interfere with the breakdown of certain drugs, magnifying their potency. It's best not to take any drugs with grapefruit juice unless the drug interaction profile of the medication is well known.
Second, taking flavonoid supplements is not the way to go. UC Davis' Dr. Mitchell cautions people not to think they can just take a supplement instead of consuming more fruits and vegetables. Whole foods supply the added benefits of vitamins, minerals and fiber.
Furthermore, the dosage furnished by supplements can vary widely but is likely to be much higher than what you'd receive from a healthy, balanced diet. Reseachers have yet to determine exactly what levels of flavonoids are optimally beneficial, or even whether flavonoids become harmful at very high doses. As with all supplements, flavonoid supplements are not stringently regulated by the FDA.
"Much about flavonoids still remains to be discovered," observes Dr. Mitchell, "and it's important not to view them as the latest fad cure-all." Her advice echoes what your mother once told you: The most positive thing you can do for your health is to eat more fruits and vegetables.
If you're curious to learn about more whole food sources of flavonoids, the USDA has an online database of 225 foods and their flavonoid content. You can find it at www.nal.usda.gov/fnic/foodcomp/Data/Flav/flav.html.