Quercetin is an increasingly well-known representative of the group of polyphenols and flavonoids, which are characterized as natural colorants particularly by their light yellow color (from the Latin flavus; yellow). Flavonoids are biologically active plant compounds that have, for example, antioxidant and anti-inflammatory effects in humans. However, the body cannot produce quercetin on its own and therefore absorbs it through food. A normal Western diet contains about 15 mg to 40 mg of quercetin daily.
Occurrence of Quercetin in Foods
The name Quercetin is derived from the Latin word Quercētum which means oak forest and emphasizes the plant origin. Larger amounts of the molecule can be 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), as well as various teas (black tea 2 mg per 100 g). Quercetin mainly accumulates in the outer plant parts such as the skin of the apple.
Onions (especially their skins) are particularly rich in the vital substance quercetin.
How much quercetin is contained in foods?
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. Depending on the growing season, these values can fluctuate significantly. You can find a detailed list of several hundred foods here.
| Food | Quercetin content in mg per 100g |
| Capers | 233.84 |
| Dill | 55.15 |
| Oregano | 42.0 |
| Onions | 24.3 |
| Apples | 19.36 |
| Spring onions | 12.6 |
| Blueberries | 7.67 |
| Black tea | 2.19 |
How much quercetin do we absorb through food?
Before we get to the dosages from the studies, let's take a quick look at the natural quercetin intake.About 70-80% of all flavonoids that we consume with food are in the form of Quercetin. This molecule occurs in various configurations in nature, mostly in combination with different sugar molecules. However, this "sugared" form is absorbed poorly by our body, as Quercetin is a fat-soluble molecule. In this Japanese study, it was precisely measured how much Quercetin people consumed in summer and winter. The result: About 15.5-16.2mg of Quercetin per day. What dosage of Quercetin is recommended? Let's compare this with the studies: Most investigations have (so far) been conducted on animals.Quercetin has been extensively researched in mice, as it is believed to have effects against dementia. The dosages vary between 5mg per kg of body weight and 100mg per kg of body weight. Studies have found that a safe amount of 1000 mg of quercetin per day in humans..
In this study , the mice received 100mg of quercetin per kg of body weight for 8 days, and the researchers found that this improved the functioning of the mitochondria in the brain.
Conclusion on Quercetin
Quercetin rightly carries 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 its diverse properties make quercetin an exciting candidate for longevity research. Additionally, this secondary plant substance has many useful effects for everyday life.
Sources
Literature
- Hickson, L. J., Langhi Prata, L., et al. (2019). Senolytics decrease senescent cells in humans: Preliminary report from a clinical trial of * plus quercetin in individuals with diabetic kidney disease. EBioMedicine, 47, 446–456. Link
- Kirkland, J. L., & Tchkonia, T. (2020). Senolytic drugs: from discovery to translation. Journal of internal medicine, 288(5), 518–536. Link
- Salehi, B., Machin, L., Monzote, L., et al. . (2020). Therapeutic Potential of Quercetin: New Insights and Perspectives for Human Health. ACS omega, 5(20), 11849–11872. Link
- Bhagwat, S., Haytowitz, D. B., & Holden, J. M. (2014). USDA database for the flavonoid content of selected foods, Release 3.1. US Department of Agriculture: Beltsville, MD, USA.
- Escande, C., Nin, V., Price, N. L., et al. (2013). Flavonoid apigenin is an inhibitor of the NAD+ ase CD38: implications for cellular NAD+ metabolism, protein acetylation, and treatment of metabolic syndrome. Diabetes, 62(4), 1084–1093. Link
- Deepika, and Pawan Kumar Maurya. “Health Benefits of Quercetin in Age-Related Diseases.” Molecules (Basel, Switzerland) vol. 27,8 2498. 13 Apr. 2022, Link
- Mlcek, Jiri et al. “Quercetin and Its Anti-Allergic Immune Response.” Molecules (Basel, Switzerland) vol. 21,5 623. 12 May. 2016, Link
- Nishimuro, Haruno et al. “Estimated daily intake and seasonal food sources of quercetin in Japan.” Nutrients vol. 7,4 2345-58. 2 Apr. 2015, Link
- Li, Yao et al. “Quercetin, Inflammation and Immunity.” Nutrients vol. 8,3 167. 15 Mar. 2016, Link
- Babaei, Fatemeh et al. “Quercetin in Food: Possible Mechanisms of Its Effect on Memory.” Journal of food science vol. 83,9 (2018): 2280-2287. Link
- Nakagawa, Toshiyuki et al. “Improvement of memory recall by quercetin in rodent contextual fear conditioning and human early-stage Alzheimer’s disease patients.” Neuroreport vol. 27,9 (2016): 671-6. Link
Grafiken
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