The five flavors of foods include
Pungent foods include green onion, chive, clove, parsley and coriander.
Sweet foods include sugar, cherry, chestnut and banana.
Sour foods include lemon, pear, plum and mango.
Bitter foods include hops, lettuce, radish leaf and vinegar (I list vinegar as bitter because the Chinese call vinegar "bitter wine." Vinegar tastes both sour and bitter; it is common for some foods to have two simultaneous flavors).
Salty foods include salt, kelp and seaweed.
Let's take the sweet flavor as an example, that acts on the stomach and spleen.
It is common knowledge among Chinese and Western dietitians, that eating sweet foods will put on weight, but Chinese and Western dietitians give different explanations.
According to Western dietitians, eating sweet foods puts on weight because sweet foods contain a large number of calories; according to Chinese dietitians, eating sweet foods will put on weight because sweet foods can act on the stomach and spleen, which are in charge of digestive functions.
In other words, in Chinese diet, sweet foods are considered capable of improving the digestive functions, which is why they are good for people with a weak digestive system.
Some foods have one flavor, but others may have two or three. Undoubtedly, the flavors of many foods are very difficult to determine precisely, but the Chinese have done it through many centuries of experience.
The process may look like this: At the beginning, some foods with obvious flavors are found to act on some internal organs and perform specific actions in the human body. The basic relationships between flavors and internal organs and the actions are studied and analyzed by a process in science called the inductive method.
As time goes on, other foods whose flavors are more difficult to determine may be found capable of acting upon some internal organs and performing some specific actions. The flavors of such foods are determined on the basis of their organic effects and specific actions. This process in science is called the deductive method.