Quercetin
Quercetin
Dr. med. Heinz Lüscher
The phytochemical is found in many plant-based foods, is well researched and has various interesting health-promoting effects.
What is quercetin and where is it found?
It is a yellow natural pigment that belongs to the secondary plant substances, or more precisely to the group of flavonoids. It is contained in many plants, which produce the substance to protect themselves against harmful environmental influences such as UV radiation, predators, fungi or microorganisms. Accordingly, the highest concentrations are found in peel, bark and petals. Capers contain particularly large quantities. However, as hardly anyone eats huge quantities of capers, it is more interesting to know that the substance is also found in high quantities in onions or apples, for example, especially in old varieties. In this country, onions are probably the most important source of quercetin, especially red onions.
Japanese string tree as a source of quercetin
The Japanese string tree (Sophora japonica), whose flowers and buds contain a lot of quercetin, has a somewhat less common origin. Its natural range extends from Japan via Korea to China, but it is now also planted in our parks and gardens. The fruit clusters of the string tree resemble strings of pearls in appearance, which is why it is also known as the pearl string tree. The tree is very robust, it tolerates heat and drought without any problems and can live for several hundred years. It can only achieve this with a good defense system.
Effects
The positive properties of quercetin have long been known to science and the substance has been researched for over 150 years. Quercetin is above all a highly potent antioxidant, i.e. it helps to scavenge and neutralize free radicals. These are known to contribute to inflammation, accelerate the ageing process and promote a number of chronic diseases such as heart disease. Quercetin also alleviates the symptoms of allergies, bronchial asthma and viral infections of the upper respiratory tract. Athletes or people under increased stress also enjoy better physical performance and recovery. The development of AGEs is also inhibited. AGEs (advanced glycation end products) are involved in a large number of diseases of civilisation and typical age-related diseases and yet are virtually unknown among doctors. Find out more about AGEs in our interview with Dr Achim Refisch. For example, caper extract (which, as mentioned, contains a high amount of quercetin) inhibits the further development of advanced AGE precursors. This has even been proven for one of these precursors in a human randomised controlled trial (RCT). In addition, caper extract can occupy the RAGE receptor on the cell wall and thus prevent AGEs from docking.
The effects at a glance:
- Highly antioxidant
- Anti-inflammatory
- Antiallergic
- Immunomodulatory
- Delays ageing due to senolytic effect
- Antiviral
- AGE development is inhibited
Indications
- Allergies, asthma
- Viral infections (especially of the upper respiratory tract)
- Sport, physical strain
- Injuries
- Inflammations
- Prevention of diseases caused by free radicals
- Protection against hyperglycemic damage
- Inhibition of AGEs
I do not recommend quercetin on its own, but rather in combination with other effective plant substances. For example, in preparations to strengthen the body and psyche (e.g. with extracts from grape seeds, roseroot, reishi, brown algae and dandelion), in a sophisticated anti-inflammatory product to treat leaky gut (with vitamins B12, C and E, folic acid, beta-carotene and alpha-lipoic acid) or in a product to combat AGEs (e.g. with capers, black garlic, noni, olive oil polyphenols, brown algae, rosemary, etc.).
Studies
Quercetin for inflammation and the immune system: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4808895/
Quercetin bei Allergien: https://aacijournal.biomedcentral.com/articles/10.1186/s13223-020-00434-0#:~:text=Quercetin%20is%20a%20naturally%20occurring,antibody%20releasing%20by%20B%20cells
