Black coffee can help defecation to a certain extent, but the effect is not obvious. Black coffee contains more caffeine, caffeine is a stimulating substance, it can stimulate intestinal peristalsis, promote defecation, if there is a slight constipation, you can drink some black coffee, on the excretion of a certain degree of help, but also can improve the body metabolism. But if the constipation is more serious, simply drink black coffee may not achieve better results. Normally, it is best not to drink too much black coffee, so as not to cause gastrointestinal tract stimulation, discomfort symptoms, and if there are duodenal ulcer, gastric ulcer and other diseases, it is best not to drink black coffee. Need to maintain a light diet, eat more vegetables and fruits.