Quercetin and cancer
What is quercetin
Quercetin is a natural flavonoid found in many fruits, vegetables, and plants. It has antioxidant and anti-inflammatory properties that have shown potential in the prevention and treatment of cancer.
How quercetin works
Quercetin’s potential against cancer is believed to stem from several mechanisms:
Antioxidants
Quercetin can neutralize free radicals that can damage cells and contribute to cancer development.
Anti-inflammatory
Chronic inflammation is associated with an increased risk of cancer. Quercetin’s anti-inflammatory properties can therefore be beneficial.
Inhibits cancer cell growth
Quercetin can disrupt cancer cells’ signaling pathways and prevent them from growing and spreading.
Strengthens the immune system
Quercetin can strengthen the immune system’s ability to fight cancer cells.
Metabolic reprogramming and signaling pathways
Recent research shows that quercetin can interfere with how cancer cells use fat and energy to survive. By blocking specific growth signals, quercetin makes it harder for the tumor to grow and spread.
Studies also suggest that quercetin works particularly well when combined with other substances; for example, a strong synergistic effect against breast cancer has been observed when combined with sulforaphane [4, 9].
Overcoming bioavailability challenges
A challenge with quercetin is that the body normally has difficulty absorbing it in large enough quantities. Therefore, researchers are working on new solutions, such as wrapping the substance in tiny fat particles (liposomes) or using a “nano-gel” [6, 8].
These methods help quercetin penetrate the cancer cells’ protective shield, making the treatment far more effective than standard supplements [5, 6].
Benefits of quercetin
Potentially preventive effect
Studies have shown that a high intake of quercetin-rich foods may be associated with a lower risk of developing certain types of cancer.
Support for conventional treatment
Some studies suggest that quercetin can improve the effect of chemotherapy and radiation therapy and reduce side effects [4, 9].
Relatively few side effects
Quercetin is generally considered safe when taken in moderate doses from foods or dietary supplements.
Disadvantages of quercetin
Limited evidence
More research is needed to confirm quercetin’s effectiveness in cancer prevention and treatment.
Interactions with medication
Quercetin can interact with certain medications, so it is important to talk to your doctor before taking it.
Side effects at high doses
High doses of quercetin can cause side effects such as stomach discomfort, diarrhea, and headache.
Research
Research into quercetin’s cancer-fighting properties is still ongoing. Several laboratory and animal studies have shown promising results, but more comprehensive clinical studies are needed to confirm the effect in humans [1, 2].
Conclusion
Quercetin is a natural flavonoid found in many fruits and vegetables that has antioxidant and anti-inflammatory properties. It appears to have potential in the fight against cancer by combating free radicals, reducing inflammation, inhibiting cancer cell growth, and strengthening the immune system. Some studies suggest that a high intake of quercetin may be associated with a lower risk of certain types of cancer and can help improve the effect of chemotherapy and radiation therapy.
Although there are promising results, much of the research is still at an early stage, and we need more studies to understand how quercetin works in humans. It is also important to be aware that it can interact with certain medications and cause milder side effects at high doses. Quercetin should be considered as a supplement that can support a healthy lifestyle, but not as a replacement for traditional treatments. With more research, quercetin may gain a more important role in the overall approach to cancer treatment and prevention.
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Links
[1] The potential anti-cancer effects of quercetin on blood, prostate and lung cancers (Frontiers, 2023)
- Content: Review article examining the potential anti-cancer effects of quercetin.
[2] Quercetin and cancer (PubMed, 2020)
- Content: Review article on quercetin and cancer.
[3] Quercetin (Memorial Sloan Kettering Cancer Center, 2023)
- Content: General information about quercetin from a leading cancer center.
[4] The role of quercetin in modulating lipid metabolism and enhancing chemotherapy via the STAT3-CPT1B pathway in pancreatic cancer (PubMed, 2025)
- Content: In vitro study showing that quercetin has an anti-cancer effect by disrupting cancer cells’ lipid metabolism via the STAT3 signaling pathway, and also shows an enhanced therapeutic effect when combined with the chemotherapy drug gemcitabine.
[5] Structural related oxidovanadium(IV)-flavonoid complexes. Influence on their anticancer effects (PubMed, 2025)
- Content: In vitro study showing that by binding the metal vanadium to flavonoids such as quercetin, researchers have enhanced their anti-cancer effect. The combination converts the normally protective flavonoids into “pro-oxidants” that selectively kill lung cancer cells by creating targeted oxidative stress, while largely sparing normal cells.
[6] Quercetin liposomes conjugated with hyaluronidase: An efficient drug delivery system to block pancreatic cancer (PubMed, 2025)
- Content: In vitro study showing that researchers have developed a new ‘2-in-1’ strategy against pancreatic cancer, where an enzyme first breaks down the tumor’s protective shield. This then allows the active substance, quercetin, to penetrate deeply and kill the now vulnerable cancer cells.
[7] Unveiling the mechanisms of Tianjihuang in hepatocellular carcinoma: a network pharmacology and molecular docking study (PubMed, 2025)
- Content: In vitro study showing that a leaf extract from the medicinal plant Tabebuia pallida, which contains active substances such as quercetin and lapachol, shows strong anti-cancer effect by forcing cancer cells into programmed cell death (apoptosis).
[8] Assessment of Cytotoxic Effects of Quercetin Nanoemulgel on Different Skin Cancer cell lines (PubMed, 2025)
- Content: In vitro study indicating that a “nanoemulgel” is an effective delivery method that improves both the solubility and the therapeutic effect of the substance quercetin.
[9] Synergistic Inhibition of Breast Carcinoma Cell Proliferation by Quercetin and Sulforaphane via Activation of the ERK/MAPK Pathway (PubMed, 2025)
- Content: In vitro study showing that a combination of the dietary supplements quercetin and sulforaphane has a strong synergistic and cell-killing effect against breast cancer cells. The effect is achieved by creating destructive oxidative stress and blocking the central ERK/MAPK growth signaling pathway.
Page created:
July 1, 2024, Last revised June 9, 2025
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