Can Coffee Cause Gas and an Upset Stomach?

If you like coffee, you probably look forward to drinking it each morning. But this morning kick-start may turn your day sour if your morning coffee and an upset stomach go together.

Coffee can aggravate ​acid reflux​, one of the causes of gastrointestinal reflux disorder, or GERD, according to the Mayo Clinic. GERD is a common cause of stomach upset or abdominal pain. A study reported in the July 2016 issue of the ​European Journal of Sport Science​ showed a modest positive correlation between caffeine intake with other foods that cause gas and lower gastrointestinal distress.

The connection between coffee and GERD is a weak one, however. According to a September 2012 study in the journal ​Food Science and Technology Research​, the number of GERD cases are increasing worldwide, and coffee use is often discouraged in GERD patients. Epidemiological reports show that coffee can irritate the stomach, the study says. But a definitive link hasn't been established.

A study published in the January 2018 issue of the journal ​Gut and Liver​ reiterated older concerns about the link between coffee consumption and other dietary modifications and GERD. The study said people who gave up coffee, among other foods, showed ​little or no improvement​ in their symptoms. The study did show that a combination of medical therapy and lifestyle modifications does help with GERD symptoms.

​Read more:​ The 10 Worst Foods for Acid Reflux

Most studies that show any link between coffee and upset stomach are from observations rather than scientific links, according to an April 2016 study in ​Comprehensive Reviews in Food Science and Food Safety​. One possibility is that roasting coffee to produce dark or light beans may contribute to stomach irritation.

According to a study published in February 2014 in the journal ​Molecular Nutrition and Food Research​, a chemical compound called N-methylpyridinium, or N-MP, contained in higher ratios in dark blends of coffee, may cause stomach upset. Researchers concluded, however, that more studies are needed.

Coffee contains ​chlorogenic acid​, which causes high stomach acid levels and more gastric acid production. That may actually help people with stomach issues, according to a study in the September 2014 issue of ​Biomolecules & Therapeutics​. Coffee may not be the cause of stomach irritation, but you'll still want to limit your intake to four 8-ounce cups daily.

​Read more:​ Should You Cut Dairy From Your Diet?

If you drink cream or milk with your coffee, that may be the problem. If you are lactose intolerant, even a tiny splash of coffee creamer that contains dairy can cause stomach problems, according to a January 2019 article in Harvard Health Publishing. Some coffee creamers listed as being dairy free still have lactose, according to the article. So try to look for creamers that are truly dairy free.

Lactose intolerance can cause stomach upset, bloating, cramps and flatulence. So if you have gas after drinking coffee with cream, it may be that you are lactose intolerant. If you feel a coffee or iced coffee stomach ache, check the additives in your creamer.

Lactose intolerance can be genetic, according to Harvard Health. It can also be caused by a bacterial infection or other gastrointestinal disorder. So if you think you are lactose intolerant, you should get a definitive test from your doctor. If you test positive, you can choose to either eliminate lactose entirely from your diet or take enzyme substitutes. You should discuss this with your doctor.