Diet containing purple potatoes may lower the risk of colon cancer

A diet containing plenty of purple potatoes and other colourful fruits and vegetables may lower the risk of colon cancer and inflammatory bowel diseases, claim researchers, including those of Indian origin.

Colourful plants, including the purple potato, contain bioactive compounds, such as anthocyanins and phenolic acids, that have been linked to cancer prevention. Understanding how these compounds work on a molecular level could be an initial step towards finding treatments for cancer, researchers said.

“What we are learning is that food is a double-edge sword - it may promote disease, but it may also help prevent chronic diseases, like colon cancer,” said Jairam K P Vanamala, associate professor at Pennsylvania State University in the US.

In the study, pigs that were served a high calorie diet supplemented with purple-fleshed potatoes had less colonic mucosal interleukin-6 (IL-6) compared to a control group. IL-6 is a protein that is important in inflammation, and elevated IL-6 levels are correlated with proteins, such as Ki-67, that are linked to the spread and growth of cancer cells, said Vanamala.

The findings, published in the Journal of Nutritional Biochemistry, show that eating whole foods that contain macronutrients - substances that humans need in large amounts, such as proteins - as well as micro- and phytonutrients, such as vitamins, carotenoids and flavonoids, may be effective in altering the IL-6 pathway.

Vanamala said these findings reinforce recent research that suggests cultures with plant-based diets tend to have lower colon cancer rates than cultures with meat-based diets. Colon cancer is a leading killer in many Western countries, which tend to include more meat and less fruits and vegetables, he added.

While the researchers used purple potatoes in this study, Vanamala said other colourful fruits and vegetables could prompt similar effects. “White potatoes may have helpful compounds, but the purple potatoes have much greater concentrations of these anti-inflammatory, anti-oxidant compounds,” said Vanamala.

Another advantage of using whole foods for cancer treatment is that it would benefit the agriculture industry and likely help small farmers around the world, said researchers, including Sridhar Radhakrishnan and Lavanya Reddivari, also from Penn State. “Instead of promoting a pill, we can promote fruits and vegetables that are very rich in anti-inflammatory compounds to counter the growing problem of chronic disease,” they said.

The researchers fed the animals three different diets: a standard diet with 5 % fat; a high-calorie diet, with 17 % added dry fat and 3-4 % added endogenous fat; and a high fat diet supplemented with purple-fleshed potatoes.

The expression of IL-6 was six times lower in pigs that ate the purple potato-enhanced feed compared to the control group. Researchers used both uncooked and baked potatoes and found similar effects. Vanamala said that the pig model was used because the digestive system is very similar to the human digestive system, more so than in mice.

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