Topic summary contributed by volunteer(s): Dawn Handschuh

Onions and Cancer

When it comes to eating nutritious foods that may play a role in cancer prevention, studies have shown the two best vegetable families for preventing cancers include cruciferous vegetables (like broccoli, kale, cauliflower and cabbage), and alliums (including garlic, onions and leeks). Both types of vegetables provide a host of benefits and can aid in preventing diseases.

Natural plant-derived compounds found in onions, along with broccoli, green tea and strawberries, can suppress the “engine-of-aging” enzyme Target of Rapamycin (TOR), the enzyme that regulates cellular growth and proliferation in the human body. Higher TOR expression has been seen in breast cancer tumors.

Onions and Disease Prevention

Onions and garlic possess powerful anti-blood clotting qualities when consumed raw, for example, chopped in salads or salsas, or as an ingredient in baba ghanoush, an eggplant dip. This is good news for those concerned about their risk of heart attack or stroke.

People are continuously exposed to a wide range of dioxins in cigarette smoke, exhaust fumes, cooked meat and fish, and dairy products.  More than 90% of the dioxins we absorb are absorbed through diet. Fortunately, phytonutrients in fruits, vegetables, tea, red wine and beans block the effects of dioxins. Just a tablespoon of raw red onion daily may cut dioxin toxicity in half. But to maintain the beneficial effects of these immune-stimulating properties, we need to continue eating foods containing these phytonutrients every day.

Onions also contain phytonutrients that may inhibit monoamine oxidase—an enzyme that has been linked to depression.

Maintaining Antioxidants in Onions 

Many vegetables lose some antioxidant content when cooked. One study of 20 vegetables determined the worst cooking method to preserve antioxidants is boiling, followed by pressure cooking, baking and frying. The gentlest cooking method is microwaving, which preserves 97.3% of the antioxidants. Interestingly, artichokes, beets and onions weren’t affected by cooking at all.