Purple vegetables and fruits contain abundant anthocyanins which can effectively resist oxidation, prevent high blood pressure and protect eyesight. The nutritional value of purple food is much higher than that of red food, black food or white food. According to the medical experts, a large number of anthocyanins are contained in cherry, eggplant and purple grapes. People can moderately increase the intake of the food mentioned above to supplement the nutrient so as to prevent the formation of heart disease and cerebral apoplexy. The nutrient can also defer the aging, prevent cancer and enhance the memory for the human body. The number of purple food is relatively few in our daily life. The food mainly includes dried purple seaweed, eggplant, blueberry, grapes and so on. Eggplant contains abundant vitamin P which can help people decrease the blood pressure and cholesterol. However, the nature of eggplant is cold. People with weak physical constitution should not eat eggplant excessively. Blueberry contains the largest number of anthocyanins among all the purple food. In fact, purple food does not just have high nutritional value. They can adjust the mood for people at the same time. For example, the unique substances contained in grape peel can resist high blood pressure so as to balance the mental mood for people. At the same time, the grape juice can increase the amount of vitamin E and anti-oxidant inside the blood plasma. In addition, the purple food can also protect the eyes for the human body. According to the medical research, the free radicals inside the human body can hurt the internal organs to cause excessive oxidation, aging and even death. Anthocyanins can effectively resist the hurt caused by free radicals. The ability of anti-oxidation of anthocyanins is 30 to 50 times higher than that of vitamin C and that of vitamin E. Among all the internal organs, eyes can be most easily hurt by free radicals. Therefore, the experts advise people to increase the intake of purple vegetables and fruits in everyday life so as to prevent nyctalopia, cataract and other eye diseases. Nowadays, the experts have developed various kinds of purple food for the edible use among people. For example, the food like tomato, carrot and potato in purple have been developed on the market. Therefore, it is convenient for people to supplement anthocyanins for themselves to keep young and healthy by increasing the intake of purple food in daily life.