1, the main nutrients of vegetables are minerals, vitamins, fiber and so on. The higher the content of these substances, the higher the nutritional value of vegetables. In addition, the content of water and dietary fiber in vegetables is also an important nutritional quality index. Generally, vegetables with high water content and less dietary fiber have better freshness and higher edible value. But from the perspective of health care, dietary fiber is also an essential nutrient.

The nutritional content of vegetables should not be underestimated. According to FAO's statistics in 1990, 90% of vitamin C and 60% of vitamin A necessary for human body come from vegetables, which shows the great contribution of vegetables to human health.

In addition, there are many phytochemicals in vegetables that are recognized as beneficial to human health, such as carotenoids, dipropylene compounds, methyl sulfur compounds and so on. Many vegetables also contain unique trace elements, which have special health care effects on human body, such as lycopene in tomatoes and prostaglandin in onions.

2. Many components in fresh fruit are water-soluble, and there are soluble plant fibers such as pectin, which can reduce the cholesterol level in blood together with vitamin C. Its digestion and absorption do not require the mixing of complex digestive juices, and it can quickly enter the small intestine through the stomach for absorption. The absorption rate on an empty stomach is much higher than that after meals.

Fruit is a low-calorie food, and its average calorie is only a quarter of that of pasta with the same weight, and about a tenth of that of meat such as pork. It is easier to grasp the total intake by eating advanced low-calorie foods. Many fruits themselves are easily oxidized and deteriorated. Eating fruit first can shorten its residence time in the stomach, reduce the degree of oxidative corruption and reduce the possible adverse effects on the body.