Strictly speaking, food compatibility does not exist. There are many reasons for diarrhea, including the characteristics of food itself, the role of microorganisms, the role of special substances, and even their own reasons, the lack of trace elements, intestinal diseases, and even some substance poisoning. The digestive system is greatly affected by the activities of the nervous system. Some people will have symptoms of digestive system when they are slightly nervous: irritable bowel syndrome.

With that in mind, let's look at bananas and peaches. Personally, it is due to the different tolerance of individual intestines to food. Bananas also have a lot of dietary fiber, and peaches also have a lot of pectin. These substances can not be digested by people, which will stimulate intestinal peristalsis, and poor tolerance may also cause diarrhea. Or the food itself is not hygienic. In our daily life, it is very unreliable to judge the cleanliness of food by personal feelings. The number and types of microorganisms (this is the key) are very important reasons (most so-called foods are illusions caused by microorganisms). As for milkshake, it may not contain fruit, so we won't discuss it.

Finally, I want to say that this question itself is not rigorous. The first is the source problem. A certain number of samples are needed to investigate a certain law, and accidental phenomena are very weak in statistics.