I’ve come across the idea so many times, and can’t seem to wrap my head around it. Why do people keep telling me that coffee is bad on an empty stomach? Why do people think it hurts your stomach with its acidity? I’ve heard that stomach acid can burn through steel, so what difference is acidic water going to make? Well, here’s what I could find about drinking coffee on an empty stomach.
Coffee seems to affect each person differently, but however it affects you, that’s what you will get – regardless of food in your stomach. No need to worry about it. However, read on for more info.
Acidity on the pH scale
For those of you who vaguely remember the pH scale and need a refresher, the scale goes from 1-14. Pure water is a 7, right in the middle. The lower the number, the more acidic it is; the higher, the more basic.
If water is 7, where’s coffee? Well, that depends if there’s milk in it, which would make it more neutral.
Black coffee ranges from high acid at 4.3 (Kenyan coffee), medium at 4.5 (Panama coffee), and low at 4.6 (Sumatran). While the 0.3 difference may seem small, keep in mind that the difference between a 4 and a 5 on the pH scale is 10x.
So, where does stomach (gastric) acid land on this scale? Between 1.5 and 3.5. That’s quite a lot of variance, but it’s almost 10x more acidic than even the most acidic coffee.
Fun fact: Beer tends to be around 4 on the pH, so it’s actually more acidic than coffee.
If all this is true, why does it seem to bother some stomachs?
Myth 1: It causes stomach problems
Well, there’s some evidence that the bitterness in coffee may cause the stomach to produce more gastric acid. It seems that the coffee’s acidity itself doesn’t matter much, but the beverage has other facets that can affect acid reflux and other reactions. (Source 1, 2)
This leads many people to believe that it is unhealthy for you, especially if there’s nothing in your stomach to cushion the extra acid.
However, there’s not much evidence supporting the idea coffee has any negative effects on your stomach – empty or not. (Source)
What it seems to boil down to is how you react to coffee in general.
Believe it or not, but some people regularly experience heartburn, indigestion, or vomiting, though this is unaffected by the contents of their stomach.
Myth 2: It raises stress hormones.
There’s a hormone called cortisol, and it’s known as the stress hormone. It has several important roles, but it spikes in the morning to help you wake up.
Coffee has been found to spike cortisol in some people, but not everyone. Some believe that it is dangerous to raise cortisol when your levels are already high.
However, it seems as though the effect is minor in most coffee drinkers, and that people who enjoy coffee regularly actually show no real increase in cortisol. (source)
As well, if it does cause a spike, it’s temporary. If there’s a health complication caused by prolonged, excessive cortisol in the system, it is likely caused by something else.
So, it seems this idea is nixed also.
Drinking coffee without food could cause it to digest more rapidly and make you a little more jittery than usual since, like alcohol, there won’t be anything to slow the absorption of the caffeine.
As well, if you’re anything like me, you may end up drinking more coffee if you’re not eating something alongside it. For me, I tend to keep knocking ‘em back over a couple of hours if I’ve skipped breakfast, which ends up making me a bit wired.
If that’s you, docs suggest that 400mg of caffeine per day is probably a good cut off point, which would be between 4-5 cups.
But again, drinking it on an empty stomach has no effect on the overall amount consumed.
Finally, there’s the Nocebo effect. You’ve probably heard of the placebo effect – getting a reaction from a ineffective treatment simply because you believe it works (and sometimes even when you don’t)? Well, the nocebo effect is the same but flipped: it’s when you expect a bad effect and get it.
So, if you believe that coffee on an empty stomach bothers you, then you may cause that very thing to happen. This could be similar to many people’s beliefs about MSG. There was an experiment that resulted in the original discovery of the “Chinese Restaurant Effect”. At the time, people believed two things: 1) MSG caused allergy-like reactions in people; 2) Chinese food used a lot of MSG.
Just to be clear, there is little evidence that MSG causes any of these effects and it is found naturally in meat. To test this theory, an experiment was run where people were given either Italian food with lots of MSG, or Chinese food with no MSG. The results showed that people who believed they reacted strongly to MSG made a lot of complaints about the Chinese food, but had no problem from the Italian. This is the power of the nocebo – the participants were not lying, they legitimately believed they were having a physical reaction.
And so it likely is with coffee on an empty stomach.
In effect, if you have issues drinking coffee with food, then you’ll have the same issues on an empty stomach.
However, if you don’t find any issues enjoying coffee with food, then you should be fine without food, also.
People just seem to want to believe that coffee is unhealthy on an empty stomach and that the acid is also somehow bad because… acid. But if that’s true, then orange juice (pH: 3.3 to 4.2) should be worse, and no one seems to be telling you to avoid the OJ in the morning.