Tips to Brew Coffee That Won't Irritate Your Stomach

Drinking coffee has health benefits, some studies show. But for some people, coffee seems to stir up digestive issues. In fact, some studies suggest that it could cause heartburn, indigestion, and acid reflux.

Two iced coffees in glass mugs on an outside table
Michelle Gibson / Getty Images

To solve this problem, scientists have explored ways to adjust the compounds in coffee to make a gentler brew. This article discusses what's known about coffee's role in stomach woes, and whether drinking certain types of coffee can make the experience less gut-wrenching.

Don't Worry Too Much About Acidity

Coffee contains several types of acids, but there isn't much research to suggest that those acids are what's causing your stomach upset.

To understand how the acids in coffee affect your body, it's helpful to know how acid is measured. In scientific terms, acids are measured on the pH scale. The lower the pH, the more acidic a drink is. Cranberry juice, for example, has a pH of around 2.5.

Different kinds of coffee have different levels of acidity. Researchers have pegged the acidity of coffee somewhere between 4.85 and 5.13. According to some studies, hot-brewed coffee has higher amounts of acid than cold-brewed coffee.

Certain varieties of coffee are also naturally less acidic. The difference could be because they were grown at a lower elevation or were dried differently.

Here's the key: It isn't the acid in the coffee that's the culprit. It's the acid in your stomach.

Drinking coffee can increase stomach acid. But that doesn't automatically mean you'll have indigestion. A 2016 study found that while drinking coffee did increase stomach acid, it didn't cause intestinal problems for the people in the study.

Some people might enjoy the taste of coffee with a lower acid content. Low-acid coffee tends to be smoother and milder than coffee with a higher acid level. However, others could miss what they describe as the “brightness” of a brew with its natural acidity intact.

Whether you prefer a more or less acidic flavor profile, you should know that the acid in coffee isn't likely to be the cause of digestive problems.

Consider a Darker Roast

A 2014 study showed that a dark roast coffee contained a balance of chemicals that produced less stomach acids than a medium roast. The dark roast had higher amounts of a chemical compound called NMP. It also had lower amounts of two other compounds known as C5HTs and chlorogenic acids (CGAs).

Researchers found that this ratio of high NMP to low C5HTs and CGAs caused the stomach to produce less acid. That means there were fewer gastric juices to bring on heartburn.

NMP alone didn't have the same effect. It was the balance of chemicals that made the difference. That result makes it clear that NMP works with other compounds in coffee to lower stomach acid.

Milk May Help, Too

When you add milk to your coffee, some of the milk proteins, including α-casein, β-casein, κ-casein, α-lactalbumin, and β-lactoglobulin, will bind to the CGAs.

When CGA is bound by a protein, it may keep the CGAs from causing a surge in stomach acid. That may because it is not as easily absorbed by your body.

In a 2019 study, researchers found that adding milk to coffee did not trigger acid reflux.

Of course, milk is not a good option for everyone. If your body doesn't digest milk easily, adding dairy milk could make things worse, not better.

Try a New Variety

New coffee varieties come on the market all the time. There isn't much research on how these varieties could affect digestive symptoms, but they may be worth a try.

Double-Fermented Coffee

Coffee is typically fermented once. After the coffee cherries are picked, they're placed in water. In the water, bacteria break down the fruit and separate it from the coffee bean. Fermentation has a number of health benefits.

Some coffee makers add a second fermentation. The process is sometimes called a “double soak.” Coffee from Kenya is known for double-soaking.

Makers of double-fermented coffees claim that double-soaking yields a coffee that’s easier on the stomach. The idea is that the double soak removes the “bitter notes” and makes it better for people with digestive issues.

However, there’s no evidence yet that double fermenting lowers the amount of stomach acid the stomach makes.

Green (Unroasted) Coffee

Green coffee is a variety of coffee bean that has not been roasted. Without roasting the beans, the CGA and NMP content of the brewed coffee are not going to be altered. The final cup may or may not lower stomach acid.

Coffee makers claim the green bean makes a smoother drink, but whether this variety leads to fewer symptoms may vary from person to person.

Don't Worry Too Much about Caffeine

It's no secret that lots of people drink coffee for the caffeine. Research on whether caffeine causes stomach problems has mixed results.

Some studies have shown that coffee and caffeine can worsen irritable bowel syndrome (IBS), a digestive disorder that causes frequent gas, cramping, and diarrhea or constipation.

And a 2017 study suggests that caffeine's bitter taste triggers the body to spike the production of stomach acid.

Still, research reviews show that drinking caffeinated coffee does not seem to increase heartburn symptoms in most people.

It’s thought that the chemical compounds in coffee that stimulate stomach acid interact with each other no matter how much caffeine is in the coffee.

It's About What Works for You

Sensitivity to coffee—in all its forms—may turn out to be highly personal.

While broad recommendations can be made from scientific studies, there are genetic variations that may influence how any one person reacts to the compounds in coffee.

The coffee that one person swears by and is able to drink without having heartburn may not work the same way for someone else. Trying different brands and brewing methods may be a part of finding a coffee that is easier to digest.


Coffee can cause stomach upset, heartburn, and reflux symptoms in some people. If you're one of them, you may want to try a few different varieties to see if any reduce your symptoms.

Some coffees claim to be milder and less irritating. So far, there's not much research to prove that low-acid, double-fermented, or green coffees are easier on your digestive system.

Some people add milk to ease the effects. Others prefer a decaffeinated coffee. There's some research to support both of these methods.

A Word From Verywell

Coffee research, like coffee drinking, is on the rise. Even so, there’s still so much more to learn about how coffee affects your body.

For that reason, a certain amount of trial and error might be needed because coffee makers don’t typically advertise the NMP and CGA content of their beans.

If you like to start the morning with coffee, you may want to note how you feel after trying a new brew. With the vast array of coffees on the market, there’s likely to be one that comes with less stomach upset.

Frequently Asked Questions

  • What is the average pH of coffee?

    Around 5. In one study, the pH level of hot-brewed coffee was between 4.85 and 5.10. The pH of cold-brew coffee was nearly identical: from 4.96 to 5.13.

  • Does adding salt to coffee make it less acidic?

    Although salt can reduce the bitter taste of coffee and other beverages containing caffeine,there's no evidence it lowers the acidity.

13 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading

By Amber J. Tresca
Amber J. Tresca is a freelance writer and speaker who covers digestive conditions, including IBD. She was diagnosed with ulcerative colitis at age 16.