Why Does Coffee Upset My Stomach?

There might be a lot of things to bellyache about with regards to coffee—how it always seems to find its way onto your new white shirt or the long line at the café each morning—but one thing that might be more avoidable than you think is the actual pain coffee can cause. Many people complain about the wear and tear they feel after drinking a cup, and there are several plausible reasons for this agony instead of ecstasy. First, however, we need to dispel the longstanding myth that “acidity” is the culprit.

New Toys12 Coffee Products You Never Knew You NeededFor specialty-coffee professionals (that is, baristas and roasters and coffee importers), “acidity” is actually a positive attribute: It’s the term used to describe the fruit-like sparkle a certain coffee will have in its flavor profile. Think about how your mouth tingles when you bite into a Granny Smith apple, the opposite reaction to a Red Delicious. That’s the green apple’s “perceived acidity” on the palate, the effervescence that gives it that tart, arguably more interesting flavor. Both apples are actually going to be relatively similar on the pH scale: The fruit generally falls between a 3.3–3.9 pH, slightly acidic. For scale, bananas are around 4.5–5.2, slightly closer to neutral.

Guess what else rates at about a 5 on the pH scale? That’s right: coffee.

That means that whatever’s causing you tummy unrest is probably not the pH acidity of your morning cup. (Unless you also find yourself sensitive to bananas, in which case, I wish you luck and lots of Tums out there.) You’re probably not imagining the troubles, however, so what is the more likely cause?

These are the reasons why coffee upsets your stomach:

1. Your brew is off. Look, I’m not saying you’re not brewing amazing coffee, just, you know, maybe something’s a little… hm… well, we have to start our diagnosis somewhere, and it just might be that your recipe is what’s doing you in. Coffee that’s brewed too strong might sit on your stomach heavily or wreak some havoc in the digestion; coffee that’s over-extracted (read: extremely bitter) will have more agita-producing compounds in it than a proper brew. If this is the case, however, it might be a fix as easy as 1, 2, 3—as in, adding or subtracting 1, 2, or 3 grams of coffee grounds to your ratio to settle the score (and settle your system).

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2. You add irritants. Milk and sugar: They taste great and they’re comforting, they make a coffee feel like a little treat. Unfortunately, they can also exacerbate that unpleasant rumble because they can irritate an already touchy stomach even more, adding insult to injury. Furthermore, the combination of sugar, dairy, and caffeinated hot liquid might be just enough of a confusing slurry that it’s hard to tell whether one or all are doing the dirty work. Many people become so used to adding cream to their coffee that they actually forget it’s dairy at all, which could mean potentially overlooking a lactose intolerance. Try cutting back or eliminating either sugar or dairy for a while to see if it helps. (Check out this guide to non-dairy milk if you’re looking for alternatives.)

3. You’re getting too wired. Some people are simply ultra-sensitive to caffeine, and low tolerance can express itself in more ways than just sleepless nights and leg jitters. Caffeine is an alkaloid, a compound that exists in certain plants as a natural pesticide, designed to stun, paralyze, or sterilize invaders that try to feed on the fruit and leaves. I’m not calling you a pest, but I am saying that you might be overdoing it on the human equivalent of Deet. Some types of coffee—specifically one called Robusta, which is commonly found in cheaper coffees like blends you’d find at diners, or delis, or gas stations—is naturally very high in caffeine, because it grows at lower altitudes where there are more insects and diseases around to make a nuisance. Almost no coffee advertises itself as Robusta, however, so it can be hard to detect unless you recognize the flavor—a flavor that is usually vastly improved by milk and sugar, which, unfortunately, also makes it harder to detect (and, also, see #2). Sneaky!

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4. You need something to dunk. An empty stomach is an invitation for disaster. Drinking coffee while eating something mild and complementary—I’m talking about oatmeal or a piece of brioche toast here, not smothered chilaquiles—can help grease the digestion wheels (so to speak) and minimize the effect of whatever it is in the coffee that bugs you. Don’t dunk your oatmeal, though: Stick to the toast for dunking.

5. Actually a few other hundred (maybe thousand) reasons. Caffeine, oils, chlorogenic acid, phenylindanes, quinolactones, melanoidins, other made-up-sounding words—there are more than a thousand known compounds that exist inside every coffee bean, and any one of them could be what’s ailing you. The fact is—well, coffee is a drug, with stimulating properties, like nicotine, like cocaine, and like opium (all alkaloids, as well). While some drugs make some people feel great, some drugs make some people feel terrible, and your mileage may vary. The great thing about coffee, though, is that there’s relatively little harm in trying out different types, and even different suppliers, to see if there’s one that suits you better.

So, how can you make coffee that doesn’t upset your stomach?

In short, here are a few possible remedies for that churning feeling:

  • Tweak your recipe to make your brew a touch less strong, or to make sure it’s not over-extracted.
  • Reduce how much milk and/or sugar you add to your brew, or curb them completely.
  • Try to avoid supercharged Robusta coffee by drinking high-quality, and yes, higher-cost Arabica beans. You might also cut back the amount of coffee you drink by about a half cup per day until you’ve reached a kind of happy equilibrium.
  • Don’t drink coffee on an empty stomach, especially first thing in the morning.
  • Keep trying to find the perfect beans for your belly by experimenting with different roast levels (lighten up if you normally go dark, or vice versa), origins (a nice mild Costa Rican for a change?), and brewing methods (swap out the espresso for a cup of filter coffee).

See our guide to The Best Coffee Subscriptions for cool beans.

Related Video: What’s the Difference Between AeroPress and French Press Coffee?


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