Human nutrition is the process by which substances in food are transformed into body tissues and provide energy for the full range of physical and mental activities that make up human life. Antioxidants that usually taken through diet and have an important role in inhibition of stress due to oxidation that reason for beginning and development of numerous diseases such as cancer, and much other disease such as diabetes and also inflammation. There are certain gaps in literature about the different activities in compounds that exhibit functions in vegetables and fruits. Different free radical leads to oxidative stress to the particular cell and ultimately causes the cancer. The natural phenolic compounds have received increasing interest in the last years, since a great amount of them can be found in plants and consumption of vegetables and beverages with a high level of such compounds may reduce the risk of development of several diseases due to their antioxidant power, among other factors. Kaempferol as one of the flavonoids that main function involved in binding with cells of the cancer and ultimately kills the cancer cells. Anthocyanin mainly the type of the major compound in the outer portion of the skin of the onions The colour of the red showing the activities against the free radicals depending on the type as well as the nature of the chemical compound. Quercetin as the valuable type of the flavonoids that have been used in the purpose of the preventing diseases associated with the bacteria as well as the viruses. Different free radical leads to oxidative stress to the particular cell and ultimately causes the cancer.