Compounds found in purple potatoes may help kill colon cancer stem cells and limit the spread of the cancer, new research claims.
Baked purple-fleshed potatoes suppressed the growth of colon cancer tumours in petri dishes and in mice by targeting the cancer's stem cells.
Attacking stem cells is an effective way to counter cancer, according to study leader Jairam KP Vanamala, associate professor of food sciences at Penn State University, and faculty member at the Penn State Hershey Cancer Institute.
He told reporters: "You might want to compare cancer stem cells to roots of the weeds. You may cut the weed, but as long as the roots are still there, the weeds will keep growing back and, likewise, if the cancer stem cells are still present, the cancer can still grow and spread."
The researchers, who released their findings in the Journal of Nutritional Biochemistry, used a baked purple potato because potatoes are widely consumed and typically baked before they are consumed. They wanted to make sure the vegetables maintained their anti-cancer properties even after cooking.
In the initial laboratory study, the researchers found that the baked potato extract suppressed the spread of colon cancer stem cells while increasing their deaths. Researchers then tested the effect of whole baked purple potatoes on mice with colon cancer and found similar results.
The portion size for a human would be about the same as eating a medium size purple-fleshed potato for lunch and dinner, or one large purple-fleshed potato per day.
According to the researchers, there may be several substances in purple potatoes that work simultaneously on multiple pathways to help kill the colon cancer stem cells, including anthocyanins and chlorogenic acid, and resistant starch.
"Our earlier work and other research studies suggest that potatoes, including purple potatoes, contain resistant starch, which serves as a food for the gut bacteria, that the bacteria can covert to beneficial short-chain fatty acids such as butyric acid," Vanamala said. "The butyric acid regulates immune function in the gut, suppresses chronic inflammation and may also help to cause cancer cells to self-destruct."
In addition to resistant starch, the same colour compounds that give potatoes - as well as other fruits and vegetables - a rainbow of vibrant colours may be effective in suppressing cancer growth, he added.
"When you eat from the rainbow, instead of one compound, you have thousands of compounds, working on different pathways to suppress the growth of cancer stem cells," said Vanamala. "Because cancer is such a complex disease, a silver bullet approach is just not possible for most cancers."
The next step would be to test the whole food approach using purple potatoes in humans for disease prevention and treatment strategies. The researchers also plan to test the purple potatoes on other forms of cancer.