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.
Lots of studies show an association between increased intake of garlic and reduced risk of certain cancers, such as stomach cancer, colon cancer, esophagus cancer, pancreas cancer, and breast cancer. And a previous study concluded that eating raw garlic may help cut risk of lung cancer almost in half.
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.
Garlic and Onion Soup Recipe:
1 head of garlic
1 whole medium-large onion
1/4 cup olive oil
Peel every clove of the head of garlic.
Slice the cloves of garlic thin and cut into strips.
Peel the onion. Cut the onion in half and slice very thin.
Heat olive oil in saute pan. Lightly saute the slivers of garlic until softer. Do not brown.
Add onions, saute until onions become soft and translucent.
Sprinkle with salt and pepper.
Add water and simmer for 5-10 minutes.
Adjust salt and pepper to taste.
Serve in a bowl.
Sources and references: