The nutrients of vegetables mainly include minerals, vitamins, fibers, etc. the higher the content of these substances, the higher the nutritional value of vegetables. In addition, the contents of water and dietary fiber in vegetables are also important nutritional quality indicators. Generally, vegetables with high water content and less dietary fiber have better freshness and higher edible value. However, from the perspective of health care, dietary fiber is also an essential nutrient. The nutrients of vegetables should not be underestimated. According to the statistics of FAO in 1990, 90% of vitamin C and 60% of vitamin A are from vegetables, which shows that vegetables make a great contribution to human health. In addition, there are many phytochemicals in vegetables that are recognized as beneficial to human health, such as carotenoids, propylene compounds, methyl sulfur compounds, etc. many vegetables also contain unique trace elements and have special health care effects on human body, such as lycopene in western red persimmon, prostaglandin in onion, etc.
It is estimated that more than 2 billion or more people in the world are caused by environmental pollution, which leads to a variety of diseases. How to solve the problem of generating a large number of oxygen free radicals due to environmental pollution has attracted more and more attention. One of the effective ways to solve this problem is to increase antioxidants in food to synergistically remove too much destructive reactive oxygen species and reactive nitrogen. It is found that many vitamins, minerals, trace elements and related phytochemicals and enzymes in vegetables are effective antioxidants. Therefore, vegetables are not only healthy food with low sugar, low salt and low fat, but also can effectively reduce the damage of environmental pollution to human body. At the same time, vegetables also play a preventive role in various diseases.
