Researchers think the potato's resistant starch helps the gut bacteria create short-chain fatty acids, which regulate the immune system, suppress inflammation and help cancer cells to self-destruct.
So far, researchers from Penn State Hershey Cancer Institute have tested the purple-fleshed potatoes on stem cells in laboratory petri dishes and on mice, and have come up with similar positive results.
The potato stops the cancer from spreading, but, more importantly, attacks the cancer stem cells, which prevents it from recurring. They hope to test the potato on cancer patients next, and for other cancers, too.
The researchers say that baking the potato doesn't kill any of the cancer-fighting compounds, and eating one a day should be adequate.
Although they think that the potato's resistant starch is the active ingredient, the researchers say it could also be the compounds that make the potato purple that are fighting the cancer cells; if so, other 'rainbow' fruits and vegetables could have similar qualities.
Colon cancer is the second most lethal cancer, responsible for 50,000 deaths in the US alone.
(Source: Journal of Nutritional Biochemistry, 2015; doi: 10.1016/j.jnutbio.2015.08.005)