Coffee on an empty stomach: is it actually bad for you?

The cup that comes before breakfast

You're up, the kettle's on, and breakfast is a problem for later. For plenty of us the first coffee lands on an empty stomach — and sooner or later someone warns you it'll wreck your stomach, send your cortisol through the roof or mess with your blood sugar. Here's what holds up.

Why coffee can upset an empty stomach

Coffee makes the stomach produce more acid, and decaf does almost the same, so it's the coffee itself, not just the caffeine. Most people never feel a thing. But if you're prone to heartburn or reflux, or your stomach is simply the sensitive type, coffee on an empty stomach may make itself felt.

Coffee's reputation as a reflux trigger is bigger than the evidence behind it. A review of 15 studies found no significant link, and a newer one found only a small one. Your own stomach is the best guide here.

Does coffee on an empty stomach spike cortisol?

Cortisol is naturally at its highest in the morning, and caffeine does push it a little higher. But the body adapts: in people who drink coffee every day, within a few days the morning cup stops raising cortisol, even though an afternoon one still can. So the cortisol warning mostly applies to occasional coffee drinkers.

Coffee before breakfast and blood sugar

This is the one with a study behind it. At the University of Bath, 29 healthy adults had a broken night — they were woken every hour — and the next morning drank strong black coffee half an hour before a sugary drink that stood in for breakfast. Their blood sugar response to the drink came out about 50% higher. It's a small study, and a sugary drink isn't a real breakfast, but the researchers' advice is easy to follow: eat first, coffee second.

So, should you skip coffee on an empty stomach?

• No complaints from your stomach? Keep your morning cup.
• Prone to heartburn? Have a bite to eat before your coffee, or with it.
• Rough night? Save the coffee for after breakfast.
• And drink some water too — coffee doesn't replace it.

A cup that's more than coffee

If your morning cup is SmartyCoffee, there's more in it than coffee. Next to the Arabica there's MCT from coconut oil — about 3 g of fat per serving — plus hydrolyzed collagen and about 1.7 g of protein, for around 40 kcal in all and no added sugar. It isn't breakfast, but it isn't just coffee either. With 1.7 g of protein per serving, it also counts as a source of protein.

The usual rule still applies, though: if your stomach doesn't love coffee on its own, have a small snack with it.

How much caffeine is sensible

For a healthy adult, up to about 200 mg of caffeine at a time and up to about 400 mg a day are considered safe. That covers everything: coffee, tea and anything else with caffeine. One cup of SmartyCoffee is 100 mg. Not for children, or during pregnancy or breastfeeding.

If you have stomach problems or take medication, talk to your doctor. This is general information, not medical advice.

Want to try it with breakfast? There are two flavors — Mocha and Choco Fudge.