Medically reviewed by Onikepe Adegbola, MD, PhD
Coffee is a beverage created out of an infusion of roasted and grounded coffee beans. It has a favorable taste and aroma, because of which it is trendy among people of all age groups from across the world. Coffee is known for its complex nutritional content consisting of minerals, vitamins, lipids, phenolic compounds, carbohydrates, etc.
Coffee’s caloric content is approximately 100 mL/1 kCAL. Based on this, it is unlikely that coffee would cause any effects on the gastrointestinal system because any food can stimulate the gut when it has a potent amount of calorie content.
One of the significant components of coffee is the alkaloid- caffeine. According to a research article titled “Coffee and Health: A Review of Recent Human Research,” published in the Critical Reviews in Food Science and Nutrition, 100 mg of caffeine is present in a cup of coffee.
Another study conducted in 2022 titled “Effects of Coffee on the Gastrointestinal Tract: A Narrative Review and Literature Update,” published in the Nutrients, stated that caffeine with a combination of other compounds like polyphenols in coffee help in the secretion of hydrochloric acid and gastrin in the stomach. These secretions promote the digestion of lipids, proteins, and carbohydrates in the body.
A study titled “Coffee and Gastrointestinal Function: Facts and Fiction: A Review,” published in the Scandinavian Journal of Gastroenterology, also mentions that coffee might impact the cardiovascular system and nervous system because of the presence of caffeine. But effects of coffee on the gastrointestinal system cannot be solely attributed to caffeine because decaffeinated coffee also has similar gastrointestinal effects.
Coffee accelerates digestion and helps cure chronic constipation, as demonstrated in the study titled, “Does postprandial coffee intake enhance gastric emptying?: a crossover study using continuous real-time 13C breath test (BreathID system),” published in the Journal of Gastroenterology. This study showed that the consumption of coffee (caffeinated or decaffeinated) after meal intake could help stimulate the gut and promote gastric emptying. It was also suggested that coffee has the potential to treat functional gastrointestinal disorders.
The above studies have demonstrated the ability of coffee to improve digestive disorders like constipation, bloating, abdominal pain, etc., and the positive relation between coffee intake and gut health. However, many consumers of coffee complain of diarrhea. This aspect of coffee deserves further attention.
Does Coffee Cause Diarrhea?
Diarrhea is a disease characterized by watery or abnormally loose stools, and it is one of the most common gastrointestinal disorders. There are numerous causes of diarrhea, such as bacteria, viruses, parasitic pathogens, poor living conditions, poor sanitation systems, particular medications, other digestive disorders, etc.
However, one study mentioned above has also highlighted the adverse effect that coffee might have on people’s health by causing diarrhea. This adverse reaction to coffee is attributed to the levels of caffeine in the beverage. Another 2018 study titled “Guidelines for the investigation of chronic diarrhea in adults: British Society of Gastroenterology, 3rd edition,” published in Gut further corroborates this.
An original research study titled “Association of Coffee and Caffeine Intake With Irritable Bowel Syndrome in Adults,” published in Frontiers in Nutrition, studied the dietary intake and gastrointestinal health of around 3362 Iranian citizens to demonstrate the impact of coffee intake on irritable bowel syndrome (IBS). The research suggested that the odds of suffering from IBS increase due to coffee consumption, especially among women and obese adults. In fact, one of IBS symptoms is diarrhea, apart from abdominal pain, bloating, etc.
Another study titled “Coffee, sugars, and chronic diarrhea,” published in Postgraduate Medicine, revealed that dietary history is essential if chronic diarrhea is to be treated promptly. While patients with chronic diarrhea are just asked about their tobacco and alcohol intake during diagnosis, the probing into dietary history deeper shows that their coffee intake is also high. Daily intake of more than ten cups of coffee can impact this particular digestive disorder.
Most people drink milk coffee which can add to the severity of lactose intolerance and cause diarrhea. According to a study titled “Lactose Intolerance, Dairy Avoidance, and Treatment Options,” published in Nutrients, food items like coffee increase the symptoms of lactose intolerance. Coffee augments intestinal transit to deliver lactose to the intestines, thereby triggering symptoms like diarrhea.
In yet another study mentioned above, it has been stated that coffee stimulates the secretion of hormones like cholecystokinin and gastrin. These hormones are said to impact the gastrocolic reflex that controls colon motility and bowel movement.
Coffee also has a pH level ranging from five to six, making it acidic. Such a pH level of coffee can stimulate gastric acid production that can cause diarrhea due to the malabsorption of food.
How Can You Combat Diarrhea Caused By Coffee?
Some of the appropriate ways in which you can avoid getting diarrhea from coffee are mentioned below:
- Keep a check on your coffee intake. Do not consume more than 10 cups of coffee daily.
- Avoid drinking milk coffee if you are lactose intolerant.
- Switch to alternatives like French roast or espresso, which have lower caffeine levels.
- Try eating something along with a cup of coffee.
- Drinking coffee on an empty stomach must also be avoided.
- Opt for cold-brewed instead of hot-brewed coffee as it has less acidic levels.
- Consult a doctor immediately if symptoms of diarrhea persist.
There are mixed opinions about the health benefits of coffee and its impact on gut health. While it can positively affect the digestive system and help people suffering from constipation, it can also induce adverse reactions in the gastrointestinal system, causing diarrhea.
Research has shown that caffeine and acidity levels of coffee seem to be the primary reason for triggering diarrhea. But adding milk and other components like sugar, cream, etc., can also aggravate the symptoms of diarrhea caused by coffee. The need is to monitor coffee intake or go for coffee varieties that are less problematic to the stomach.
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