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Onion

Strong evidence

Active compounds

QuercetinKaempferolSulfur compoundsAnthocyanins (red onion)

Cancers studied in the literature

colonbreastprostateovarylung

Anti-cancer actions

✦Quercetin inhibits cancer cell proliferation by blocking protein kinases
✦Among the most effective foods in Béliveau studies for colon, breast and prostate
✦Red onion contains additional anthocyanins — powerful antioxidants
✦Helps control blood sugar — reduces pro-tumor insulin and IGF
✦Quercetin is anti-inflammatory and pro-apoptotic

How to prepare it

Raw is preferred (dressings, salads) to maximize quercetin. Cooked in olive oil if needed. Red onion is richer in antioxidants than white. Shallot is even more concentrated.

Recommended dosage

Daily — as the aromatic base of all meals.

⚗️ Food synergies

These foods potentiate the effects of Onion

🧄Garlic 🌱Leek, shallot & chives 🍅Tomatoes 🟡Turmeric

How to prepare it

Raw sliced onion in salads and dressings. Onion sautéed in olive oil as the aromatic base for all dishes. Raw red onion in sandwiches and tabbouleh.

Scientific sources

—Boivin D et al. — Food Chemistry 112:374-380 (2009)
—Studies on quercetin and colon and ovarian cancer

🔬 Studies from Dr. Béliveau's laboratory

All publications →

2025Molecular Biology ReportsStrong evidence

Quercetin targets TGFβ-primed human MDA-MB-231 triple-negative breast cancer cells, linking epithelial-mesenchymal transition to cell senescence and fibrosis

Pepin SK, Zgheib A, Roy ME, ANNABI B.

Quercetin (found in onions) targets triple-negative breast cancer cells — the most aggressive subtype — by blocking the TGF-β pathway involved in metastasis.

Targeting triple-negative cancer cells via TGF-β

Source: richardbeliveau.orgRead article

2012Exp Cell Res 318(8):925-35.Strong evidence

Quercetin abrogates IL-6/STAT3 signaling and inhibits glioblastoma cell line growth and migration

Michaud-Levesque J, Bousquet-Gagnon N, Béliveau R

Study published in Exp Cell Res 318(8):925-35. on the activity of onion in the context of brain.

See original publication

Source: richardbeliveau.orgRead article

2009Nutr

The Flavonols Quercetin, Kaempferol, and Myricetin Inhibit Hepatocyte Growth Factor-Induced Medulloblastoma Cell Migration J

Labbé D, Provençal M, Lamy S, Boivin D, Gingras D and Béliveau R

Study published in Nutr on the activity of onion, omega-3 in the context of brain.

See original publication

Source: richardbeliveau.orgRead article

2009Food ChemistryStrong evidence

Antiproliferative and antioxidant activities of common vegetables: A comparative study

Boivin D, Lamy S, Lord-Dufour S, Jackson J, Beaulieu E, Côté M, Moghrabi A, Barrette S, Gingras D, Béliveau R

A comparative study: garlic, leek and onions show the strongest antiproliferative activity among common vegetables — confirming their central role in cancer prevention.

Inhibition of cell proliferation, antioxidant activity

Source: richardbeliveau.orgRead article