What is quercetin?

Quercetin is an increasingly well-known representative of the group of polyphenols and flavonoids, which are natural pigments characterized in particular by their light yellow color (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 per day.

Occurrence of quercetin in food

The name quercetin is derived from the Latin word Quercētum, which means oak forest and underlines the plant origin. Larger amounts of the molecule are found in, for example, 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. In apples, it accumulates in the skin.

How much quercetin is contained in food?

The quercetin content in food varies greatly. We have listed the foods with the highest quercetin concentrations in the table. However, it should be noted that these are average values. These values can vary greatly depending on the growing season. You can find a detailed list of several hundred foods here.

How much quercetin do we get from food?

Before we get to the dosages from the studies, let's take a quick look at the 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.

This Japanese study measured exactly how much quercetin people consumed in summer and winter. The result: around 15.5-16.2mg quercetin per day.

What dosage of quercetin is recommended?

Let's compare this with the studies: Most of the studies (so far) have been carried out on animals, e.g. quercetin has been intensively researched on 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. Studies have shown that an amount of 1000 mg quercetin per day is safe in humans.

In this study , the mice were given 100mg of quercetin per kg of body weight for 8 days and the scientists found that this improved the functioning of the mitochondria 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.