Some potato skins are blue, or some sections are green. People often mistake them for fresh potatoes, which is not harmful to health. In fact, the green potato is caused by the high content of solanine, which is caused by the immature harvest, or by the sunlight during storage, which produces solanine and turns green. At this time, the content of Solanum nigrum per100g potato is as high as 500mg, which can cause acute poisoning if eaten in large quantities. Therefore, green potatoes are inedible.

Solanum nigrum can destroy human red blood cells, has strong irritation to mucosa and paralyzes the central nervous system.

It is recommended not to eat blue potatoes.