Stool thinning without blood in middle-aged and old people may or may not be normal. If it is caused by physiological reasons, such as changes in dietary structure, it is normal; if it is caused by pathological reasons, such as rectal polyps, rectal cancer, etc., it is abnormal. 1. Physiological reasons: such as changes in dietary structure, middle-aged and old people’s teeth loss, do not like to eat difficult to chew food, will consume more easy to chew fine food, and consume less dietary fiber, which will lead to the stool can not be shaped, or performance of middle-aged and old people’s stools become thin and do not carry blood. 2. Pathologic causes: (1) Rectal polyps: more common, elevated lesions on the surface of the rectal mucosa. When the stool passes through the rectum, the presence of rectal polyps leads to the narrowing of the stool discharge channel, which can lead to the situation of middle-aged and old people’s stool becoming thin without blood. (2) Rectal cancer: a malignant tumor of rectal mucosa epithelium, which is more common in middle-aged and old-aged people. When defecating, the intestinal tube becomes narrow because of the tumor, and the situation of thin stool without blood can occur. The former is normal, the latter is not normal. In addition, the middle-aged and elderly stool thin without blood may also have other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.