A specially-bred purple sweet potato could be the new weapon to fight cancer. Anthocyanin, a chemical which lowers the risk of cancer and can even slow down certain types of the disease, gives the purple color to the vegetable.

Purple sweet potato is found in market also, but this new vegetable has been specially developed in the US. The purple sweet potatoes in the grocery store don't have the same purple color on the skin and inside, as the new specially-bred purple sweet potato.

Researchers have tested two derivatives of anthocyanin taken from the potato on human colon cancer cells. It was found that growth of the cancer cells was inhibited.

Soyoung Lim, a researcher at Kansas State University said phenols are chemical compounds that have been found to have anti-aging and antioxidant components. The specially-bred purple sweet potato had a much higher total phenolic content and antioxidant capacity than the other regularly occurring purple sweet potatoes.

The newly developed purple sweet potato has a good taste also.

Dr Weiqun Wang said: 'It's kind of sweeter than normal sweet potatoes. We have always promoted it because we know it's a health food.'

The research team will conduct a follow-up study this summer that will involve treating animal cancer cells with the pigments.