Popular media outlets have made many claims about the effect of coffee on the human digestion system. Some sources claim that coffee may cause heartburn, but others tout the benefits of the drink. Luckily, scientists have come to the rescue to debunk common myths about coffee’s effect on digestion. Studies from peer-reviewed journals help shed light on how coffee truly works in the human digestive system.
Although several studies have been performed, the information about coffee and acid reflux is contradictory. According to a review of studies published in the “Scandinavian Journal of Gastroenterology,” coffee promotes acid reflux. The same study claimed that heartburn is the most commonly reported side effect of coffee drinking. However, a study from the “European Journal of Gastroenterology and Hepatology” did not find any relationship between coffee and acid reflux in healthy people or in people with gastro-esophageal reflux disease.
Indigestion and Gastric Emptying
Studies included in the review of literature that was published in the “Scandinavian Journal of Gastroenterology” indicated that coffee may delay gastric emptying, due to stomach relaxation. However, a 2001 study from the “European Journal of Clinical Investigation” concluded that coffee has no effect on gastric emptying. This study compared the gastric emptying times of people who consumed water and people who consumed coffee before liquid nutrient meals. Most studies do agree that coffee is not associated with dyspepsia, also known as indigestion, despite the conflicting data on gastric emptying times.
A study published by “The American Journal of Clinical Nutrition” investigated the effect of coffee on the gallbladder, an accessory organ of the digestive system. The study measured the plasma cholecystokinin concentrations of six healthy coffee drinkers. Cholecystokinin is a substance that signals the gallbladder to contract. The study found that both regular and decaffeinated coffee increase plasma cholecystokinin concentrations. The increased cholecystokinin levels lead to gallbladder contractions. The “Scandinavian Journal of Gastroenterology” literature review suggests that this may be why people suffering from gallstones often choose not to drink coffee.
Colon Muscle Activity
Most scientists agree that coffee stimulates colon muscle activity. In some people, digestive muscles show activity within just four minutes of coffee consumption. Usually, coffee stimulates the colon just as much as a 1000 calorie meal. A study from the “European Journal of Gastroenterology and Hepatology” found that the stimulating effect of caffeinated coffee on colon muscles was 60 percent stronger than that of water, and 23 percent stronger than that of decaffeinated coffee.
Scandinavian Journal of Gastroenterology: Coffee and Gastrointestinal Function: Facts and Fiction. A Review.
European Journal of Gastroenterology and Hepatology: Effect of Coffee on Gastro-oesophageal Reflux in Patients With Reflux Disease and Healthy Controls
European Journal of Clinical Investigation: The Effect of Coffee on Gastric Emptying and Oro-caecal Transit Time
The American Journal of Clinical Nutrition: Coffee Stimulation of Cholecystokinin Release and Gallbladder Contraction in Humans
European Journal of Gastroenterology and Hepatology: Is Coffee a Colonic Stimulant?