Alkaline food refers to the food that is metabolized and produced by the body after digestion and absorption. Generally, the acidity and alkalinity of food is determined by the type and content of minerals contained in the food, and not according to the taste of food. Alkaline food is rich in a variety of trace elements, generally containing potassium, sodium, calcium, magnesium, iron, phosphorus, chloride, sulfur 8 trace elements. Because the food contains these metal cations, after the food enters the body, through the decomposition and metabolism, the final product generated to make the body fluid alkaline, so it is alkaline food. General alkaline foods include vegetables, fruits, legumes, etc. From the point of view of nutrition, a reasonable combination of acidic food and alkaline food is the guarantee of health. However, there are some alkaline foods are special. For example, vinegar, although vinegar is acidic to eat, it produces carbon dioxide and water in the process of human metabolism and does not produce acidic substances, so vinegar also belongs to alkaline food. It generally includes vegetables, fruits and legumes, such as grapes, citrus, cucumbers, carrots and soybeans. In fact, the acidity and alkalinity of food is not determined by taste, so alkaline food may also taste acidic when eaten, such as lemon, citrus, poppy, vinegar, etc.