Buckwheat is rich in B vitamins, which has anti-cancer effect. It is also rich in trace element selenium, which also has anti-cancer effect. Fiji people in the island country rarely get cancer, which is related to the local people eating more buckwheat; Sweet potato is a high cellulose food, which can promote defecation and prevent colorectal cancer; Coix seed decoction, confirmed by modern pharmacological research, has inhibitory effect on cancer cells; Corn is rich in lysine, which has a significant effect on cancer prevention. In many countries and regions where corn is the staple food, the proportion of cancer is significantly lower than other regions.