The Allium family of vegetables includes onions, garlic, leeks, chives, shallots, and scallions. Epidemiological studies have found that increased consumption of Allium vegetables is associated with decreased risk of several cancers. For example, one large European study found striking risk reductions in the participants who consumed the greatest quantities of onions or garlic for oral, esophageal, colorectal, laryngeal, breast, ovarian, and prostate cancers. A fifty-five to eighty percent reduction of almost all major cancers. Amazing!1
Anti-cancer effects of onions and garlic Allium vegetables are rich in cancer-fighting organosulfur compounds, which are produced when the cell walls of the vegetables are broken down by chopping, crushing, or chewing. These compounds are thought to be mostly responsible for the cancer-protective effects of Allium vegetables. In scientific studies, organosulfur compounds prevent the development of cancers by detoxifying carcinogens and halting cancer cell growth. These garlic and onion phytochemicals are also anti-angiogenic, which means that they can prevent tumors from obtaining a blood supply to fuel their growth.2 In studies of breast cancer cells, garlic and onion phytochemicals have caused cell death or halted cell division, preventing the cancer cells from multiplying.3-5
Onions, garlic, and their family members also contain flavonoids and phenols. White onions are not as rich in these antioxidant compounds as yellow and red, and shallots are especially high in polyphenol levels. Red onions are particularly rich in anthocyanins (also abundant in berries) and quercetin.6 Flavonoids such as quercetin can contribute to preventing damaged cells from advancing to cancer, and also have anti-inflammatory effects that may contribute to cancer prevention.7-1
Consuming onions and garlic also might help you prevent heart disease. Onions are rich in natural chemicals called flavonoids, which can protect you from heart disease, says Vegetarian Nutrition.info., and onions also might reduce your risk of blood clots, which can lead to heart attacks and other forms of heart disease. Garlic might also decrease your risk of blood clots, help keep your arteries flexible and help reduce your blood pressure, the Linus Pauling Institute reports.
Onions and the other vegetables of the Allium family can be added to any and every vegetable dish for great flavor and anti-cancer benefits. Remember that they must be eaten raw and chewed well or chopped finely before cooking to initiate the chemical reaction that forms the protective sulfur compounds. When you cut onions and your eyes begin to tear, they are creating the anti-cancer sulfur compounds.
Allium vegetables such as onions and garlic are the richest food sources of healthy sulfur compounds, which recommends eating them regularly to obtain their full health benefits, rather than taking supplements that might contain widely varying amounts of the healthy compounds. Onions and garlic have complementary tastes, so you might eat them together in the same meals. You can also add onions to stir fry dishes and use them to flavor soups, salads and dips. The Linus Pauling Institute recommends eating garlic cloves raw, or crushing or chopping garlic cloves before cooking them to help them retain their beneficial compounds during the cooking process.
How to cut an onion to maximize anti-cancer compounds and minimize eye irritation:
- Make sure that the onion is cold before you cut it. Even putting the onion in the freezer for 5 minutes is sufficient.
- You can use a fan to blow the gaseous compounds away from you if you like.
- Cut the end of the root off with the root facing away from you, preserving as much of the onion adjacent to the root as possible. The root is the part of the onion with the highest concentration of these anti-cancer compounds.
- Make sure to then cut or chop the onion finely, slice thinly, or put it in a food processor before adding to your soup, salad, or vegetable dish to maximize the production of sulfur compounds.
References 1. Galeone C, Pelucchi C, Levi F, et al. Onion and garlic use and human cancer. Am J Clin Nutr 2006;84:1027-1032. 2. Powolny A, Singh S. Multitargeted prevention and therapy of cancer by diallyl trisulfide and related Allium vegetable-derived organosulfur compounds. Cancer Lett 2008;269:305-314. 3. Modem S, Dicarlo SE, Reddy TR. Fresh Garlic Extract Induces Growth Arrest and Morphological Differentiation of MCF7 Breast Cancer Cells. Genes Cancer 2012;3:177-186. 4. Na HK, Kim EH, Choi MA, et al. Diallyl trisulfide induces apoptosis in human breast cancer cells through ROS-mediated activation of JNK and AP-1. Biochem Pharmacol 2012. 5. Malki A, El-Saadani M, Sultan AS. Garlic constituent diallyl trisulfide induced apoptosis in MCF7 human breast cancer cells. Cancer Biol Ther 2009;8:2175-2185. 6. Slimestad R, Fossen T, Vagen IM. Onions: a source of unique dietary flavonoids. J Agric Food Chem 2007;55:10067-10080. 7. Ravasco P, Aranha MM, Borralho PM, et al. Colorectal cancer: can nutrients modulate NF-kappaB and apoptosis? Clin Nutr 2010;29:42-46. 8. Miyamoto S, Yasui Y, Ohigashi H, et al. Dietary flavonoids suppress azoxymethane-induced colonic preneoplastic lesions in male C57BL/KsJ-db/db mice. Chem Biol Interact 2010;183:276-283. 9. Shan BE, Wang MX, Li RQ. Quercetin inhibit human SW480 colon cancer growth in association with inhibition of cyclin D1 and survivin expression through Wnt/beta-catenin signaling pathway. Cancer Invest 2009;27:604-612. 10. Pierini R, Gee JM, Belshaw NJ, et al. Flavonoids and intestinal cancers. Br J Nutr 2008;99 E Suppl 1:ES53-59.