Quercetin is a plant-based chemical, called a phytochemical, that is found in some types of plants, fruits and vegetables. It is often responsible for giving plants, flowers, fruits and vegetables their color. The color in apples and red onions is caused by quercetin.
Quercetin is part of a group of phytochemicals known as flavonoids, most of which are responsible for coloring of a plant product to a certain extent. Flavonoids, and quercetin in particular, may offer a number of benefits to humans. In addition to the aesthetic value of plant coloration, they may offer the practical benefit of improving health to a certain degree.
For example, quercetin is known to have a number of different uses in the medical field. It is an antihistamine that can be used to reduce allergy symptoms. It can also be used to reduce inflammation for those who suffer from arthritis. Quercetin can also help reduce the number of free radicals in the body. These harmful particles are known to contribute to cancer and heart disease.
Quercetin can be taken in two forms. It is most commonly taken through the natural consumption of fruits and vegetables which contain significant amounts of the chemical. However, it is also available in capsule form for those who wish to take it that way. It is the method of choice for those truly expecting to use quercetin to reduce symptoms of illness.
Quercetin may be a popular natural remedy for allergies and inflammatory ailments because of its lack of side effects. There are no harmful side effects known, though it may have some interaction with certain forms of chemotherapy. More study is needed to determine whether this interaction is positive, negative or neutral.
For those wishing to use quercetin as an anthistamine, it is suggested the daily dose should not exceed 600 mg. It is recommended not to take this all at once, but in several doses throughout the day. In order to get quercetin in such numbers, it is necessary to take it as a supplement as one apple has approximately 13mg of quercetin.
Quercetin is also generally thought to be non-toxic. Studies conducted on quercetin toxicity showed no harmful effects between groups given low doses and high doses. The only side effect mentioned was that some in the high dose group experienced more weight loss than those in the low dose group.