Intestinal disorders

Gastric and duodenal ulcers (small intestine)

Gastric ulcers develop in the lining of the stomach, whilst duodenal ulcers develop in the first part of the small intestine (duodenum). Ulcers can cause abdominal pain, nausea, heartburn and a feeling of fullness, and are often associated with the bacterium Helicobater pylori²⁰.

An across-sectional study, published in 2013, could not detect a significant association of coffee consumption with upper gastrointestinal ulcer diseases, including gastric and duodenal ulcers⁵. It is worth noting that those who experience symptoms of ulcers may voluntarily reduce their coffee consumption through a perceived relationship between drinking coffee and their symptoms²¹.

Coffee and the large intestine

The colon is responsible for the re-absorption of water, as well as processing and elimination of waste products. It is also the area where the gut microflora reside, an increasingly important area of knowledge and research on gut health.

The balance of colonic motility is important to ensure waste is excreted without the complications associated with either constipation or diarrhoea. Although the effects will vary from person to person.  

Intestinal peristalsis

Peristalsis refers to the movement of food through the digestive tract.

• 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
• However, a 2024 meta-analysis reviewing the effectiveness of caffeine in reducing constipation in adults presented conflicting results and recommended further well designed studies²³

Colorectal cancer

In 2016, the International Agency for Research on Cancer (IARC) found inadequate evidence to suggest any link between coffee consumption and colorectal cancer¹⁵.

A number of large studies show no association between coffee consumption and colorectal cancer and in fact suggest that moderate coffee consumption could reduce the risk of colorectal cancer²⁴.

• A 2023 systematic review concluded that coffee drinking was associated with a significant reduction in the risk of colorectal cancer (11-24%), colon cancer(9-21%), and rectal cancer (25%). A dose response analysis suggested an 8% risk reduction at an intake of 5 cups of coffee per day. Decaffeinated coffee was also associated with a significant risk reduction²⁴

Further detailed information is available in the cancer section here.

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