What are the benefits of quercetin?
A natural molecule
Quercetin is a pigment belonging to a group of plant compounds called flavonoids.
It is extracted from different plant sources, and is present in a wide variety of foods.
It is found in fruits (apples, red or black berries, cherries), in vegetables (onions, peppers, spinach, broccoli, tomatoes), in aromatic herbs (parsley, chives, dill), in tea and red wine.
An antioxidant action
Quercetin is particularly sought after for its powerful antioxidant properties (protection against cellular aging).
It fights oxidative stress, a chemical oxidation process that accelerates the aging of our body and is involved in the onset of many diseases.
Several studies have validated its antioxidant effects.
Indeed, this study observed that a higher intake of quercetin contributes to protection against the onset of chronic diseases.
This other study showed a protective effect against age-related cognitive decline.
An anti-inflammatory and immunological action
Numerous studies have confirmed that it reduces inflammation.
In this study, a 2-month quercetin supplementation in people suffering from a chronic inflammatory disease, rheumatoid arthritis, significantly reduced the clinical symptoms of the disease, notably morning pain or pain after exertion.
Quercetin also supports natural immunity.
In another study, taking quercetin for two weeks reduced the incidence of infections in athletes stressed by exercise, and increased their immune function.
An anti-allergic action
Its anti-inflammatory and antioxidant properties make it a preferred ingredient in the treatment of allergic rhinitis and asthma.
Indeed, quercetin reduces the release of histamine, the substance responsible for the allergic reaction.
Also read | The best natural antihistamines
Numerous studies have demonstrated its effectiveness in allergic diseases, such as asthma, allergic rhinitis, or atopic dermatitis, improving clinical symptoms without side effects.
An intestinal action
It also has beneficial effects on our gut. Indeed, a study has shown that it may be effective in rebalancing the gut microbiota after antibiotic use, and could also have a prebiotic effect.
Another study shows that quercetin improves the intestinal barrier.
Which form for the best quercetin?
In capsules
It is mostly found in capsule form, generally of plant origin. The capsules contain either quercetin dihydrate or anhydrous quercetin.
The capsule has the advantage of combining effectiveness and convenience. The concentration of active ingredients is often higher than in liquids, and dosing is better controlled.
This form also provides good long-term preservation by limiting the risk of moisture and oxidation. Its portability makes it easy to carry and promotes good adherence to the treatment.
Finally, capsules often have a lower concentration of excipients.
In liquid
The liquid form allows a very good absorption of quercetin. Manufacturers encapsulate it in liposomes, lipid vesicles that facilitate its passage through the intestine.
The drawback of the liquid form is the high cost of dietary supplements, as the manufacturing process is complex.
Criteria to consider
Different forms
It exists in different forms in dietary supplements.
The form most commonly found is the quercetin dihydrate: the product then contains water molecules in addition to quercetin. It’s an inexpensive form with decent absorption.
Anhydrous quercetin is another form of quercetin that does not contain water. This form is pure and therefore more readily absorbed.
Its only drawback is its price, but its effectiveness is increased.
These two forms are found in capsules. Another form, generally in liquid formulations, is the liposomal quercetin. Its absorption is excellent, but it is rarer and more expensive.
Dosage
There are no official dosage recommendations for quercetin, but scientific studies generally use doses between 500 and 1500 mg per day for an adult depending on the conditions.
For a significant effect, it is important that the dietary supplement contain at least 500 mg of quercetin per capsule.
Capsule quality
Quercetin capsules are generally of natural origin. They are either HPMC or pullulan capsules.
- HPMC, whose proper name is hydroxypropylmethylcellulose, is derived from pine or rice cellulose, and is predominant on the dietary supplement market. It is important to choose high-quality HPMC capsules, to avoid possible traces of solvents. Hence the importance of turning to transparent supplement brands (certification regarding the quality and origin of their capsules).
- Pullulan, for its part, is produced by fermentation of tapioca starch using a fungus. Its production does not involve chemical agents, but it cannot be organic (because of the fermentation process). The shells do not contain GMOs, solvents, or allergenic substances.
Origin and traceability
How is it extracted? Where are the products manufactured? It is important to have this information in order to make your choice.
Quercetin is generally extracted from the flowers of Sophora japonica, a tree from China later introduced to the West.
Another alternative is the onion extract.
You should check the purity of the products (absence of solvents and chemical residues) and the amount of active ingredient to ensure a quality product.
Be careful, a formula claiming 95% purity may contain only 85% pure quercetin, for example with the dihydrate form where it is associated with water.
You can find the information directly on the box, on the manufacturer’s website, or upon request from the laboratory (origin of quercetin extracts, place of manufacture, batch analysis).
Organic quercetin
In organic foods, it is present in greater quantities than in non-organic foods.
On the dietary supplement market, organic quercetin is still very rare. Be vigilant! Many laboratories play on the designation “organic quercetin”, but are not certified organic.
On the box, you should find a logo or label attesting to the “Organic Farming” certification by an accredited organization.
The absence of excipients
The longer the list of ingredients, the more the concentration of active ingredients and the product quality tend to decrease.
The same applies to products combining quercetin with other molecules. The presence of preservatives, flavorings, or coating agents should be avoided, particularly silicon dioxide (nanoparticles) or magnesium stearate, which can be allergenic.
Is there a danger in consuming quercetin?
Short-term course
Naturally present in many foods, an appropriate quercetin supplementation does not pose major problems. However, it is important to follow precautions for use.
When taken as a short-term course, it can be used safely at the usual doses. As with any antioxidant, the effects of long-term supplementation are unknown.
Contraindications and adverse effects
In case of kidney or thyroid problems, it is advised to avoid taking quercetin.
If you are taking medication, I invite you to seek approval from your doctor or pharmacist before any use: it could reduce the effects of certain antibiotics, antihypertensives, antidiabetic drugs, and anticoagulants.
Finally, it can cause headaches and stomach aches, especially at high doses.
To summarize
To be sure you’re choosing the best quercetin, check:
- Form: anhydrous quercetin is better absorbed
- Dosage: the dietary supplement should contain at least 500 mg of quercetin per capsule
- Capsule quality: those made of pullulan are free from GMOs, solvents, and allergenic substances
- Origin and traceability : origin of quercetin extracts, place of manufacture, batch testing
- Absence of excipients : notably silicon dioxide (nanoparticles) or magnesium stearate, which can be allergenic
- Precautions for use: there are contraindications in case of kidney or thyroid problems, and if you take certain antibiotics, antihypertensives, antidiabetics, and anticoagulants. Ask your doctor or pharmacist for approval
