Sweet potato contains protein, starch, amino acids, pectin, dietary fiber and other vitamins and minerals, as well as more than ten kinds of trace elements such as calcium, iron, copper, selenium and phosphorus. Sweet potato is also rich in lysine and polysaccharide. Sweet potato contains a lysine, but rice and flour just lack this lysine. Sweet potato mixed with rice flour can fully supplement protein. Sweet potato contains a lot of dietary fiber, which cannot be digested and absorbed in the intestine. Can stimulate the intestine, enhance peristalsis and promote defecation. Sweet potato is famous for its low calorie and high fiber. It contains almost no fat and cholesterol and is rich in unsaturated fatty acids, which is unmatched by other foods. Dietary fiber can not only prevent the absorption of fat and cholesterol in the intestine, but also decompose cholesterol in the body, promote lipid metabolism, effectively prevent overnutrition and resist obesity, thus achieving the purpose of losing weight. Sweet potato contains a lot of starch, which can produce satiety after eating, thus reducing food intake and weight loss. Sweet potato is also rich in potassium, which can reduce the disadvantages caused by excessive salt intake, and enough potassium intake can eliminate excess sodium. Sweet potato is rich in vitamin C, carotene and folic acid. Eating sweet potatoes often helps to maintain normal folic acid levels in the human body. Eating sweet potato in daily diet can quickly neutralize the acidic substances produced by rice, flour, meat, eggs and other foods in human body, maintain the weak alkali balance of human blood, and at the same time convert carotene into vitamin A. Sweet potato contains a substance similar to estrogen, which has a certain effect on protecting human skin and delaying aging. Eating sweet potatoes can inhibit the production of melanin and prevent freckles and senile plaques.