23 May 2019 --- Coffee has long been thought to increase bowel movement, but until now researchers have not pinpointed the specific reason or mechanism why this is so. The accelerated mobilization of bowel movements has been tested in a rat model, with US researchers finding that muscles in the lower intestines and colons of rats showed increased ability to contract after just a brief period of coffee ingestion. The findings also revealed the same reaction from the rats for regular and caffeine-free coffee.