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Red Onions
Credit: Mark Weinberg

Red onions are capable of fighting off cancer more effectively than their lighter counterparts, according to a study from the University of Guelph in Ontario, Canada.

In particular, red onions contain high levels of quercetin—a flavonoid with strong clinical evidence as an anticancer compound—along with anthocyanin, the pigment that gives red onions, as well as berries, grapes, eggplant, and purple corn, their dark color. Working together, anthocyanin increases the ability of quercetin to destroy cancer cells.

In the study, researchers placed colorectal adenocarcinoma (colon cancer) cells in direct contact with quercetin from five different types of onions.

VIDEO: How to Peel and Chop an Onion

"We found onions are excellent at killing cancer cells," said Abdulmonem Murayyan, a PhD student involved in the study. "Onions activate pathways that encourage cancer cells to undergo cell death. They promote an unfavourable environment for cancer cells and they disrupt communication between cancer cells, which inhibits growth."Follow-up trials also indicated that onions can activate the same response in breast cancer cells.

We love all onions equally, but researchers found that Ontario-grown red onions killed off more breast and colon cancer cells than four other varieties of onion, which is maybe something to keep that in mind this summer as you’re building burgers, mixing salads, and grilling vegetables.

And if you're among the red onion-avoidant (like Chopped's Scott Conant, whose fierce hatred of red onions has spawned its own Tumblr universe), it's possible you're just eating them wrong. Even raw onions become less intense after soaking them in cold water, and every stir-fry gets infinitely better when you start by tossing onions over high heat. Eventually, you'll become one of those impressive kitchen pros who can flip food in the pan like it's nothing. Do it for your health, of course.