If you need a cup of coffee (or two or three) to get yourself going in the morning, you're not alone. Although many of the negative stories around coffee have been shown to be false — in fact, the brew has several health benefits — there's still confusion about the effect of coffee on digestion.
Coffee's Bowel-Stimulating Effects
Evidence linking coffee with bowel movements mostly goes back to a notable April 1990 study published in Gut, in which researchers found that 29 percent of volunteers claimed coffee made them need to poop. When the participants had their bowel activity scientifically measured, the researchers found there was indeed a marked effect, with both regular and decaffeinated coffee causing contractions in the lower bowel within four minutes.
Additionally, a November 2018 review of studies in Scientific Reports found that drinking coffee assisted in getting digestive function back on track in people who had just had abdominal surgery. The researchers found that the drink enhanced the recovery of gastrointestinal function after the procedure, and helped to get the bowels of these patients moving again.
Read more: Can Coffee Cause Bloating?
Coffee and Digestion After Meals
Aside from potentially helping with healthy bowel movements, coffee has traditionally been regarded as a digestif, which refers to a beverage that purportedly aids digestion when consumed after a meal.
While the coffee and digestion evidence isn't strong enough to suggest the brew can actually help break down food more efficiently, a July 2017 study in the Proceedings of the National Academy of Sciences outlined how caffeine stimulates release of stomach acid. In turn stomach acid is needed to aid in the digestion of proteins.
There might be a longer-term bonus to digestive health from consuming coffee as well. A February 2016 review in the journal Nutrients noted that polyphenol plant chemicals, including those found in coffee, stimulate beneficial gut bacteria and inhibit growth of harmful bugs.
Coffee and Dyspepsia
When it comes to caffeine and digestion, Harvard Health Publishing point out the stimulant's gastric acid-producing effect can also be a downside, especially as caffeine also relaxes the lower esophageal sphincter that separates the esophagus from the stomach. For those susceptible, this double whammy can have the effect of worsening acid reflux or similar dyspepsia and indigestion symptoms.
It might also pay to be cautious with coffee consumption if you have other conditions that increase gut sensitivity. The Crohn's and Colitis Foundation suggests that caffeinated drinks such as coffee should be avoided by people with irritable bowel syndrome and inflammatory bowel disease when experiencing a flare-up.
Read more: Can Drinking Coffee Cause Diarrhea?
Safe Limits for Coffee
The average person can safely consume up to four 8-ounce cups of coffee a daily without any negative health effects, though certain populations — such as pregnant women — should cut back. The limit is mostly due to the effects of caffeine on your body.
If you are particularly prone to acid reflux, the Cleveland Clinic recommends switching to decaffeinated coffee instead. Decaf isn't as acidic for the stomach, so you might experience fewer unpleasant symptoms.
- Gut: "Effect of Coffee on Distal Colon Function"
- Scientific Reports: "Effect of Postoperative Coffee Consumption on Gastrointestinal Function After Abdominal Surgery: A Systematic Review and Meta-Analysis of Randomized Controlled Trials"
- Science: "Population-Based Metagenomics Analysis Reveals Markers for Gut Microbiome Composition and Diversity"
- Harvard Health Publishing: "Take Control of Your Heartburn"
- Crohn's and Colitis Foundation: "Inflammatory Bowel Disease and Irritable Bowel Syndrome Similarities and Differences"
- Cleveland Clinic: "Lifestyle Guidelines for the Treatment of GERD"
- U.S. Food and Drug Administration: Medicines in My Home: Caffeine and Your Body
- Gut: Effect of Coffee on Distal Colon Function.