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Quercetin—The Anti-Allergy Bioflavonoid

Every spring, summer and fall millions of Americans sneeze, wheeze, drip, and sniffle their way through a world filled with trillions of airborne pollen, dust, and smoke particles. Over-the-counter anti-allergy drugs (antihistamines) tend to leave their users either sleepy or over-stimulated. Fortunately, modern nutritional science now offers a highly effective, natural and nontoxic remedy for allergies: the bioflavonoid quercetin.

Quercetin, a "cousin" of the more well-known bioflavonoid rutin, is one of a thousand or so members of the bioflavonoid family. This is a group of coloring pigments widely found throughout the plant kingdom, where they also provide plants with antioxidant protection against environmental stresses. Natural diets high in vegetables, fruit, sprouts, and whole grains typically provide a total of 1,000 to 2,000 mg. a day of a broad range of flavonoids. Blue-green algae are the usual source of quercetin, but it's also available as a food supplement.

Allergies and asthma are inflammatory conditions usually triggered by air- or food-borne pollens and chemicals called "allergens." After these allergens are absorbed into the blood (through the lungs, skin, or intestines), they cause the B cells (white blood cells) of allergy-sufferers to produce billions of molecules of the allergic antibody IgE. The IgE molecules then travel through the bloodstream until they combine to with mast cells or basophils. Mast cells (which line many blood vessels) and basophils (a type of white blood cell circulating in the bloodstream) are the main storage sites for histamine and serotonin. The IgE allergic antibody then causes the cell membranes of the mast cells/basophils to become "leaky, " allowing their storage load of histamine and serotonin to pour into the surrounding blood and tissues. The IgE-released histamine and serotonin then produce the familiar allergic symptoms of runny, swollen nose; blocked sinuses; itchy eyes; skin blotches; coughing and wheezing; etc.

Quercetin to the rescue! Quercetin has a strong affinity for mast cells and basophils. It tends to stabilize their cell membranes, preventing them from spilling their pro-inflammatory, allergy-symptom-causing load of histamine/serotonin into the surrounding blood and tissue in response to the IgE antibody. And without the release of these potent inflammatory mediators, the familiar misery of allergies simply will not occur, even though you've inhaled the pollen, animal hair, or whatever normally triggers allergy attacks.

Asthma is an allergic inflammation involving the lungs. During an asthma attack (which can be triggered by air- or food-borne pollen, dust, animal hair, chemicals, etc.), the millions of tiny air sacs within the lungs are constricted, seriously impairing breathing and causing a feeling of tightness in the chest. In addition to IgE-released histamine, the primary biochemical cause of the asthmatic symptoms is a group of fatty acid derivatives called leukotrienes (LTs). These asthma-causing LTs are made from arachidonic acid (a key fatty acid constituent of many cell membranes) by the action of two enzymes - phospholipase A2 and lipoxygenase. Quercetin is known to be a powerful inhibitor of both these enzymes. Thus it prevents the formation of asthma-causing LTs, even when the IgE antibody (formed in response to inhaled or swallowed allergens) is present in the lungs to stimulate LT Production and release. Since quercetin suppresses the release and/or production of the two primary inflammatory mediators–histamine and leukotrienes–that cause the actual symptoms of asthma, its potential benefit in the prevention and treatment of asthma is evident.

Quercetin is a safe, nontoxic substance. A report by I. Hirono et al in Cancer Letters (1981), for example, found no evidence of toxicity or carcinogenicity in rats, even when quercetin made up 10 percent of their total dietary intake.

Unfortunately, quercetin is barely soluble in water, so poor dietary absorption may limit its efficacy. Because of this, Murray, N.D., has suggested that quercetin be taken in combination with bromelain to improve its absorption. Bromelain is a natural, protein-digesting enzyme derived from pineapples. It has been used "to increase absorption of compounds, including antibiotics. Also, bromelain has powerful anti-inflammatory properties that synergize with quercetin. Bromelain inhibits several other common inflammatory mediators, including bradykinin and fibrin. It's widely used in sports medicine to reduce the pain and swelling of bruises, sprains, muscle tears, etc., for this reason.

As a clinical nutritionist I have had numerous occasions to use quercetin on allergy and asthma suffers. About 1,000 to 2,000 mg. a day, divided into three to six doses, is sufficient to control most cases of allergy and many cases of asthma. I have remained virtually allergy and asthma free for several years through daily use of quercetin, and finding it much more effective for this purpose than other bioflavonoids.

Lets Live Magazine, September, 1992