- A study of 99 individuals suggested that coffee stimulated intestinal movement in 29% of people21
- Research comparing the effect of regular and decaffeinated coffee on intestinal motility with the same amount of hot water or a full meal of 1,000 calories, showed that the effect of caffeinated coffee was as substantial as the meal, 60% stronger than water, and 23% stronger than decaffeinated coffee22
- Further work suggests that strong coffee and hot water both have a significant effect on bowel movement23
There is no indication that coffee causes diarrhoea in healthy adults and it is not possible to draw conclusions about a role for coffee consumption in constipation, since this will depend on the cause and severity of the constipation.
Irritable bowel syndrome (IBS)
- A screening exercise as part of research in the Netherlands suggests that there is no association between IBS and coffee consumption3
- Further research from Sweden found that 63% of IBS sufferers assume that their symptoms are related to meals, especially foods rich in carbohydrates and fat. In this group, coffee was associated with serious complaints such as dyspepsia and stomach pain by 10% of patients24
- Results from a questionnaire amongst IBS patients from Switzerland reviewing perceived effects of coffee drinking suggest that over two thirds of patients consumed coffee regularly, with 38% suggesting that coffee drinking has an effect (either positive or negative) on their symptoms. Interestingly, almost half of respondents who claimed to experience a negative impact of coffee consumption continued to regularly consume coffee25
In 2016 the International Agency for Research on Cancer (IARC) found inadequate evidence to suggest any link between coffee consumption and colorectal cancer30.
- A number of large literature reviews show no association between coffee consumption and colorectal cancer and in fact suggest that moderate coffee consumption could reduce the risk of colorectal cancer37-40
Further detailed information is available in the cancer section here
Other intestinal disorders
There are many other disorders of the intestine that have a variety of causes, including diverticulitis, inflammatory bowel disease, Crohn’s Disease and ulcerative colitis. There is no indication that coffee influences the course of these disorders.
- A 2017 systematic review concluded that coffee consumption tends to result in reduced risk of ulcerative colitis, but this finding is not significant and is confounded by smoking41