What is the reason why a person often has diarrhea?

Often diarrhea, mostly caused by spleen and stomach weakness, may also be suffering from chronic enteritis, or ulcerative colitis. In addition, improper diet can often cause diarrhea, such as eating raw and cold irritating food, or eating unclean, moldy food, some people eat too much, indigestion, can also cause diarrhea phenomenon.