Red onions have high amounts of quercetin, a flavonoid, and anthocyanin—the pigment that gives the onion its colour—and together they combine to kill colon and breast cancer cells, laboratory tests have found. In fact, the pigment seems to super-charge the quercetin and magnifies its 'scavenging' properties, say researchers from the University of Guelph.
They tested five different types of onion on the cancer cells. All onions contain quercetin, and so, in theory, they all have cancer-fighting qualities, but it was the red variety that stood out.
For their experiment, the researchers chose five onion varieties grown in Ontario, including the Ruby Ring red onion.
"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," lead researcher Abdulmonem Murayyan explained.
The next stage is to test the cancer-fighting powers of onions on people, he said.