Peppers are one of popular vegetables because of the combination of colour, taste and nutritional value. Peppers contain a wide array of phytochemicals and are a good source of vitamin C and carotenoids that are important nutritional antioxidants found in the human diet. Vitamin C is hypothesized to prevent cancer by inhibiting the formation of N-nitroso compounds in the stomach, and by stimulation the immune system. Vitamin C is also the most abundant water-soluble antioxidant in the human body. Carotenoids are fat-soluble antioxidants found in many fruits and vegetables and are required for human epithelial cellular differentiation. In addition, peppers were reported to contain moderate to high levels of neutral phenolics or flavonoids, phytochemicals that are important antioxidant components of a plant-based diet, other than traditional nutrients, that may reduce the risk of degenerative diseases. Flavonoids are widely distributed in the plants. Flavonoids are reported to possess many biochemical and pharmacological effects, including antioxidation, antiinflammation and antiallergy. Flavonoid intake was reported to reduce cancer risk. Flavonoids inhibited enzymes such as prostaglandin synthase, lipoxygenase and cyclooxygenase, closely related to tumorigenesis.