Is purple potato really more nutritious than sweet potato?

Sweet potato, also known as sweet potato, sweet potato, sweet potato, sweet potato and so on. , which is a favorite dual-purpose food for China people. Sweet potato is rich in nutrition, including starch, dietary fiber, carotene, vitamins A, B, C and E, and more than ten kinds of trace elements such as potassium, iron, copper, selenium and calcium.

According to records, sweet potato has many health functions. According to Compendium of Materia Medica, sweet potato has the effects of "tonifying deficiency and benefiting qi, strengthening spleen and stomach, and strengthening kidney yin". Modern scientific research has also confirmed that sweet potato helps to lose weight, relax bowels and inhibit cholesterol, thus helping to keep fit and delay aging.

Purple sweet potato is a new sweet potato variety with purple skin and purple flesh introduced from abroad in 1980s. At present, purple sweet potato varieties in China are all introduced from abroad and bred by domestic hybridization. In the market, the price of purple sweet potato is higher than that of ordinary sweet potato, so let's analyze whether it is worth the money.

Purple sweet potato basically contains all the nutrients of sweet potato, and is rich in protein, dietary fiber, vitamins and trace elements. After cultivating purple sweet potato in Japan, the differences between purple sweet potato and common sweet potato were compared. It was found that the contents of lysine, copper, manganese, potassium and zinc in purple sweet potato were 3-5 times that of common sweet potato, especially the contents of iodine and selenium were 20 times that of common varieties.

According to the analysis of American Agricultural Products Center, the nutritional value of purple sweet potato produced in the United States is much higher than that of other sweet potatoes, in which lysine, potassium, manganese and zinc are 5-8 times higher than that of ordinary sweet potatoes, while the content of iodine and selenium is more than 20 times higher than that of other sweet potatoes. For China residents whose staple food is rice and flour, the rich lysine in purple sweet potato can supplement the lack of lysine in rice and flour. Therefore, eating purple potato with rice and flour can achieve the function of protein complementarity.

Purple sweet potato is purplish red because it is rich in anthocyanins, which is not comparable to ordinary sweet potato. Anthocyanin is also a powerful antioxidant, and its ability to scavenge free radicals is stronger than that of vitamin C and vitamin E. It can not only indirectly scavenge excessive free radicals by improving the activity of antioxidant enzymes in animals, but also release electrons to supplement free radicals through redox, thus directly scavenging free radicals.

The role of anthocyanins does not stop there. More and more studies show that anthocyanins in purple sweet potato can help to limit the development of some cancers and serious vascular diseases and reduce their incidence. In addition, anthocyanins also have the functions of enhancing memory, preventing aging, preventing diabetes and obesity, and improving optic nerve. Another special advantage of purple sweet potato over common sweet potato is its rich selenium. Selenium is a component of glutathione peroxidase, which has a special contribution to scavenging free radicals in the body. Selenium is also an important factor in preventing cancer.

In terms of nutritional components, purple sweet potato is indeed richer than ordinary sweet potato, but compared with the price of ordinary sweet potato in the market, its cost performance remains to be discussed. After all, the nutrients our body needs can't be supplemented by eating a certain food. Moreover, purple sweet potato, like ordinary sweet potato, contains oxidase, which easily produces a large amount of carbon dioxide gas in the gastrointestinal tract of human body, causing abdominal distension, burping and gas production. Eating a large amount at one time will also stimulate the secretion of gastric acid, resulting in a "heartburn" feeling. Therefore, even if purple potatoes are nutritious, you can't eat too much!

About the author: Ma Guansheng, Ph.D., Professor of Nutrition and Food Hygiene Department of Peking University College of Public Health, Doctoral Supervisor, Chief Science Communication Expert of China Association for Science and Technology, has been engaged in nutrition and health research for 27 years. He is currently a member of the National Food and Nutrition Advisory Committee, an expert on women and children's issues of the the State Council Women and Children Working Committee, a member of the Expert Committee of the National Nutrition Improvement Plan for Rural Compulsory Education Students, the leader of the expert group of the pilot project of children's nutrition improvement in poverty-stricken areas, and the vice chairman of the China Nutrition Society. In 20/0/3, KLOC won the first prize ceremony for science communicators in the 6th China Health Annual General Evaluation List, "Person of the Year in Science Communication", People's Daily Health Times "Top Ten People of the Year in Healthy China Award 20 12", and China Nutrition Society won the first prize of personal nutrition science on 20/0/0, 2008.

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