Hidden inside vegetables, fruits, flowers, herbs, and grains are certain pigments that seem to do a lot more than add color to the scene. Once thought to be lacking in nutritional value, the compounds called bio flavonoids are now in the spotlight and are being given new consideration for a lot of their colorful activities. Among their other powers, research has shown, these hidden stars may have anti-inflammatory, anti-allergic, antiviral, and anti-cancer properties. Bioflavonoids were discovered in the 1930s by Albert Szent-Györgyi, a Hungarian-born American chemist who won a Nobel Prize in medicine for his work with vitamin C. He found that when combined with vitamin C in his animal studies, a substance in the rinds of citrus fruits, which he named citrin, helped strengthen the small blood vessels called capillaries. When he traced the active ingredients in citrin, Szent-Györgyi discovered a group of compounds that he named vitamin P, later to be called bioflavonoids.
Subsequently, doctors began using these compounds to treat various bleeding problems such as bruising. In 1950, though, a committee of experts decided that they were not actually vitamins, since no studies could prove that they are essential to our health. And in the late 1960s, the Food and Drug Administration determined not only that bioflavonoids were not vitamins but also that they had no nutritional value whatsoever.
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With the publication of new research, some medical experts regard these substances as powerful antioxidants, providing protection against the free-roaming, unstable molecules called free radicals. That’s a significant contribution because free radicals have been linked to cancer, heart disease, arthritis, and other ailments. Supplements are now being used to prevent and treat fragile capillaries, bleeding gums, varicose veins, hemorrhoids, bruises, diabetes, heavy menstrual bleeding, glaucoma and other vision problems, and many other conditions.
Between the date of Szent-Györgyi’s original discovery and today, a lot of laboratory work has been done. Nearly 4,000 bioflavonoids have been identified. Selected from this vast array, a much smaller number are commonly found in supplements.
One that has been studied is quercetin, found in grapes, green tea, tomatoes, onions, kale, green beans, and strawberries. Other supplements contain rutin, which comes from buckwheat and a number of other plants. A third widely available bioflavonoid is hesperidin, derived from the rinds of oranges, lemons, and other citrus fruits.
You’ll also see supplements called proanthocyanidins, or PCOs, which are primarily from red wines and grapeseed extract. In the United States, Pycnogenol is a registered trademark name for a PCO from a different source—the bark of the French maritime pine tree.
Some bioflavonoid supplements contain both hesperidin and rutin. A combination of rutin and vitamin C is sold as vitamin C complex, says Michael Janson, M.D., president of the American College for Advancement in Medicine, based in Laguna Hills, California, and author of The Vitamin Revolution in Health Care. The combination makes sense because bio-flavonoids and vitamin C work together to provide protection from free radicals, says Dr. Janson. He adds, however, that it’s usually less expensive to take vitamin C and bioflavonoid supplements separately.
SUPPLEMENTSNAPSHOT
| Bioflavonoids Individual names: Quercetin, rutin, hesperidin, and proanthocyanidins, among others. May help: Allergies, asthma, carpal tunnel syndrome, bruises, gout, high cholesterol, varicose veins, hemorrhoids, low immunity, arthritis, and sciatica. With vitamin C, used for gingivitis, colds and flu, canker sores, cold sores, menopausal discomforts, heavy menstrual bleeding, vaginitis, and genital herpes. May also strengthen capillaries, enhance connective tissue repair, decrease risk of heart disease and stroke, and help prevent cancer. Special instructions: Take with food. Good food sources: Rinds of oranges, lemons, and other citrus fruits; onions, kale, green beans, broccoli, endive, celery, cranberries, tomatoes, red bell peppers, apples, green and black tea, grapes, and red wine. Cautions and possible side effects: Generally regarded as safe. |
A Case for Quercetin
Among the bioflavonoids, quercetin is perhaps the most highly regarded as a supplement to reduce inflammation and relieve asthma and allergies.
The main causes of run-of-the-mill allergy symptoms are histamine and leukotrienes, biochemicals that are released by your immune system to defend your body against invading allergens. For many allergies, antihistamine drugs do just what their name implies: They help prevent histamines from getting into your cells and causing symptoms such as congestion and sneezing, says Elliott Middleton Jr., M.D., professor emeritus of medicine at the State University of New York at Buffalo.
In preventing allergy symptoms, quercetin and other bioflavonoids act somewhat differently. Instead of blocking the pathways into the cells, they inhibit the manufacture and release of histamine and leukotrienes in the first place, explains Dr. Middleton. Plus, it seems that they can inhibit the action of these allergy-causing chemicals even after they’ve been released.
Because of quercetin’s anti-allergy properties, some naturopathic doctors regularly prescribe supplements. During hay fever season, Jennifer Brett, N.D., a naturopathic doctor at the Wilton Naturopathic Center in Stratford, Connecticut, recommends quercetin for many of her patients, particularly those who are allergic to ragweed and leaf mold. According to Dr. Brett, quercetin helps reduce her patients’ allergy symptoms, including itchy eyes, runny noses, and scratchy throats. She’s found that it’s also effective for people who have asthma, which is sometimes touched off by allergic reactions. If they take the bioflavonoid, Dr. Brett says, they don’t need to rely as much on inhalers for relief.
Something for the Heart.......and More
Quercetin and other bioflavonoids have also been targeted for bio- detective work because of their ability to prevent heart disease and strokes. When Dutch scientists studied the eating patterns of 805 men ages 65 to 84, they discovered that those who consumed the most bioflavonoids—specifically from tea, onions, and apples—were less likely to die from a heart attack than those who ate less. The more bioflavonoids the men consumed, the lower their risk of heart attack. Those who got the most preventive paybacks were consuming the equivalent of 4 cups of tea, an apple, and 1¼8 cup of onions a day.
In another study from the Netherlands, researchers gathered health and dietary information from 552 men ages 50 to 69. Fifteen years later, during follow-up examinations, the researchers found that those who consumed a high amount of bioflavonoids—mostly from black tea—had a 73 percent lower risk of stroke than those with a low intake.
Bioflavonoids appear to reduce the risk of cardiovascular disease by making small blood cells called platelets less sticky, explains Joe Vinson, Ph.D., professor of chemistry at the University of Scranton in Pennsylvania. Sticky platelets can cause blood clots that ultimately result in heart attacks.
Bioflavonoids also act as antioxidants and may prevent the oxidation of LDL cholesterol, which is believed to be a leading cause of atherosclerosis (hardening of the arteries).
Preventing Cancer and Cataracts
These multitalented pigments also show some promise in cancer prevention, according to Dr. Middleton. So far, the evidence comes from animal and laboratory studies in which bioflavonoids were used. "They have some remarkable effects," says Dr. Middleton, "but the one that especially fascinates me is that certain bioflavonoids can convert malignant cells into normal cells. It’s extraordinary."
Cataract prevention is another area where bioflavonoids, particularly quercetin, may help. When cataracts develop, obscuring normal vision, substances called sugar-protein complexes are deposited on the lens of the eye. According to Dr. Janson, quercetin reduces the activity of an enzyme that leads to these deposits. When the deposits are reduced, there’s less risk of developing cataracts.
Finally, bioflavonoids are believed by some to enhance vitamin C activity in situations where the vitamin alone is ineffective and to improve the strength of blood vessels and connective tissue. You can get the benefit of those actions in a number of ways. Stronger blood vessels mean less bruising and offer some protection against the development of varicose veins and hemorrhoids. There’s also less chance of developing bleeding gums.
Bioflavonoids may strengthen and repair connective tissue by stimulating the synthesis of collagen, the fibrous protein that helps hold cells together. They also inhibit the breakdown of collagen, which means that connective tissue between your cells is more likely to stay strong and unbroken. This benefits the nervous system and may reduce allergy symptoms, such as inflammation.
The Pluses of Getting Enough
While the many benefits of bioflavonoids are being explored, experts are still trying to decide whether most of us can benefit from supplementation. Some say that we get all the bioflavonoids we need from our diets and that supplementing provides no additional benefits. Others argue that supplements provide extra protection and help fill the gaps when our diets are lacking.
"There are many good things in your food that you can’t isolate in a supplement," says Dr. Vinson, who believes that bioflavonoid supplements aren’t usually necessary.
Dr. Janson agrees that food is the preferred source of bioflavonoids, but he recommends supplementation as well. "Therapeutic doses for allergies, for example, are higher than you can get from diet. If people eat a wide variety of plant-based foods, they’ll probably get a good supply of bioflavonoids. But I still believe there are benefits to supplementation." Based on this view, Dr. Janson regularly prescribes bioflavonoids to his patients.
