What Is It?
Quercetin may be a major reason why eating an apple a day has been associated with good health. Quercetin, primarily found in apples and onions, is a type of flavonoid (plant pigment) and serves as a building block for other members of the flavonoid family.
Quercetin may be beneficial in combating a host of disorders from asthma to cancer. Among people with high dietary intakes of quercetin and other flavonoids, study results show lower rates of stomach, lung, pancreatic, and breast cancers. In one study, lung cancer risk was reduced 58% among people who ate the most apples compared to people who ate fewer apples. In the lens of the eye, quercetin inhibits the build up of sorbitol (a type of sugar) which could otherwise lead to cataract formation. Additionally, quercetin may be useful in relieving hay fever, sinusitis, and asthma because it can reduce inflammation in the airways and lungs and block allergic reactions to pollen.
Asthma 250-500 mg 3 times a day
Crohn’s Disease 400 mg 3 times a day
Gout 500 mg twice a day
Heartburn 500 mg 3 times a day quercetin or mixed bioflavonoids (with or without added bromelain)
Quercetin is one of the flavonoids–naturally ocurring plant pigments with a wide variety of positive effects in the body. Flavonoids can act as antioxidants, protecting us from free-radical damage. They also help prevent the accumulation of LDL (“bad”) cholesterol along our arteries and, as natural antihistamines, may minimize allergic reactions.
HOW IT HELPS ASTHMA
Quercetin is thought to benefit asthma in two basic ways. First, it inhibits the release of histamine, the chemical that your body naturally produces in response to allergens, which can lead to watery eyes, nasal congestion, and other discomforts. Second, quercetin appears to inhibit your body’s output of inflammation-producing compounds (prostaglandins and leukotrienes) that are known to tighten your airway tubes, making it hard for you to breathe freely.
WHAT TO LOOK FOR
Many common foods–apples, onions, various berries, and nuts–are rich in quercetin. Even popular herbs such as ginkgo biloba and St. John’s wort contain quercetin. There are now concentrated formulations of quercetin available in supplement form, too.
The medical situations requiring quercetin virtually always require some extra vitamin C. For this reason supplements often combine these two nutrients. This is doubly useful because vitamin C and quercetin appear to enhance and protect each other. The enzyme bromelain, extracted from pineapple, enhances the absorption of quercetin as well. So you’ll frequently see a combination of quercetin and bromelain, or of quercetin, bromelain, and vitamin C.
Make sure your combination product contains adequate amounts of quercetin–250 mg in each capsule, for example.
No toxic reactions have been reported with the use of quercetin.
David Edelberg, MD