Quercetin is an increasingly well-known representative of the group of polyphenols and flavonoids, which as natural pigments are characterized in particular by their bright yellow colour (from the Latin flavus; yellow). Flavonoids are biologically active plant compounds that have antioxidant and anti-inflammatory effects in humans, for example. However, the body cannot produce quercetin itself and therefore absorbs it through food. A normal Western diet contains around 15 mg to 40 mg quercetin daily.
Occurrence of quercetin in food
The name quercetin is derived from the Latin word Quercētum , which means oak forest and emphasizes the plant origin. Larger amounts of the molecule are found in capers (234 mg per 100 g) and onions (11-33 mg per 100 g), apples and berries (both 2-5 mg per 100 g), and various teas (black tea 2 mg per 100 g). Quercetin accumulates mainly in the outer parts of the plant . Correspondingly in the skin of the apple.
Onions (especially their skin) are particularly rich in the vital substance quercetin.
How much quercetin is contained in food?
The amount of quercetin in food varies greatly. We have listed the foods with the highest quercetin concentrations in the table. However, it must be said that these are average values. Depending on the growing season, these values can fluctuate greatly. You can find a detailed list of several hundred foods here.
| Lebensmittel | Content of quercetin in mg per 100g |
| caper | 233.84 |
| Dill | 55.15 |
| Oregano | 42.0 |
| Zwiebeln | 24.3 |
| Apples | 19.36 |
| Spring onions | 12.6 |
| Blaubeeren | 7.67 |
| Schwarztee | 2.19 |
How much quercetin do we take in through food?
Before we get to the dosages from the studies, let's take a quick look at natural quercetin intake. Around 70-80% of all flavonoids that we ingest with food contain a form of quercetin. This molecule occurs in various configurations in nature, mostly in combination with different sugar molecules. However, this "saccharified" form is less easily absorbed by our body, as quercetin is a fat-soluble molecule.
In this Japanese study exactly how much quercetin people consumed in summer and winter was measured. The result: About 15.5-16.2mg quercetin per day .
What dosage of quercetin is recommended
Compare this with the studies: Most of the studies (so far) have been carried out on animals,z.B quercetin has been intensively researched in mice, as it is expected to have effects against dementia. The dosages vary between 5mg per kg body weight and 100mg per kg body weight. In studies, an amount of 1000 mg quercetin per day was found to be safe in humans .
In this study , mice were given 100mg of quercetin per kg of body weight for 8 days and the scientists found that this improved mitochondrial function in the brain.
Conclusion on quercetin
Quercetin rightly bears its name as the "king of flavonoids" . This molecule has already demonstrated its positive effects in many animal and cell studies and the initial results in humans are also promising. It remains to be seen to what extent quercetin can be used, but it is precisely its diverse properties that make quercetin an exciting candidate for longevity research. And the secondary plant substance also has all kinds of other useful effects for everyday life.
