Everyone knows that vegetables are he althy, but not everyone knows how to prepare them for consumption so that the nutrients in them are preserved. For example, some vegetables lose their vitamin C and folic acid content during cooking and it is recommended to eat them raw. Still others must be heat treated.
The heat treatment of tomatoes allows their dense cell walls to be destroyed and the anti-cancer compound lycopene to be released. This compound reduces the risk of heart attacks. The processing of mushrooms leads to a concentration of the polysaccharides contained in them, which inhibit the growth of tumors. Similarly, processing works on asparagus and its anti-cancer antioxidants.
In general, vegetables from the Cabbage family (broccoli, cauliflower, Brussels sprouts, cabbage and white, red, curly and Chinese cabbage) are rich in glucosinolates - substances that activate the immune system and fight cancer. And heat treatment destroys them. Therefore, only light processing or fresh consumption is allowed.
Onions in general can only be eaten raw. Chopped onions have a high concentration of anti-cancer compounds known as organosulfides. They make us cry when we cut onions, and the heat destroys them.
Pepper, spinach, carrots and many other vegetables are rich in vitamin C. Processing them reduces its level. That's why cooking them with steam or in a pressure cooker allows to preserve not only the vitamins, but the carotenoids and antioxidants that reduce the risk of eye disease and cancer.