It’s common to have a cup of coffee in the morning in most coffee-drinking nations. Coffee can help us start our day by giving us a slight jolt of energy to accompany what most would consider our primary productive time. It’s also usual to wake up early in the morning with the urge to go to the bathroom. In some cases, this urge postpones itself to after we’ve had our first cup of joe. For some, this correlation is curious – and for others, it begs several questions: does coffee play a role in digestion? Is it a laxative or a diuretic, or neither? Can it help with indigestion, or does it worsen it? And how does coffee contribute to the digestion of a breakfast meal, versus its effects on an empty stomach?
The short answer is that coffee – and more directly, caffeine – does have an effect on digestion. But caffeine’s effects on the body’s digestive and endocrine systems can be a little complex and give way to a greater conversation about how caffeine affects the brain in general. A cup or two of coffee in the morning will kickstart a series of different processes in the body, not the least of which is gastric peristalsis. Coffee can curb the metabolic process, and given you drink enough of it (or consume your coffee with milk and sugar), it’ll get your insulin and glucagon going as well. Although black coffee has close to no calories, the caffeine in a large cup of coffee is enough to simulate a full meal in terms of gastric movement. In this sense, drinking coffee on an empty stomach may trigger heartburn or acid reflux if you’re prone to a little indigestion. Whether coffee first thing in the morning is good or bad mostly depends on whether you’re skipping breakfast, and how you generally feel after your first cup. As for how that changes your digestion, it might speed up the process of getting food from the stomach, to the other end of your tract.
Caffeine, Digestion, and Pooping
Caffeine is a psychoactive alkaloid found most famously in coffee, but also in tea, and select other plants like cacao, yerba maté, guayusa, and guarana. Like its fellow alkaloid cocaine, caffeine is a stimulant, and is often found in over-the-counter analgesic combination drugs (in conjunction with acetaminophen) and cold medication. Like other stimulants, caffeine boosts the heartrate, gets norepinephrine going, and generally leaves you feeling energetic. Caffeine is a mild stimulant and doesn’t share cocaine’s surge in dopamine, or its sheer addictiveness, although caffeine addiction has been recorded (and is a rather mild affliction). Alongside its boost to the heart, caffeine also affects the body’s metabolism. This means it generally lets you burn more calories, despite toning down your appetite somewhat.
It also has an effect on gastric peristalsis, which is the coordinated, rhythmic activation of the muscles in the stomach and intestines. Peristalsis is triggered whenever you swallow, and within the rest of the gastrointestinal tract, its activation is controlled completely by the autonomic nervous system. This activation of muscles pushes food down through the GI tract all the way to your other end. Coffee speeds this process up. This doesn’t usually affect the absorption of nutrients in a significant way, but it does potentially lead to a looser stool, because it causes defecation to come sooner rather than later, which leaves little time for the reabsorption of water in the final stages of digestion (which is what causes a firmer stool).
Caffeine is fully absorbed into the body within about 45 minutes, with peak concentrations in the blood taking place about 15 minutes after oral ingestion. It then takes several hours for caffeine to fully metabolize, at which point the liver does its job and caffeine’s effects cease. Caffeine clearance and metabolism is heavily affected by a number of other factors, including diet, pregnancy, menstruation, alcohol consumption, smoking, medication, liver health, and certain diseases. Certain genes are responsible for determining how an individual responds to caffeine, how quickly they metabolize it, and how high their tolerance for caffeine is. Caffeine tolerance can also change over time, especially if taken daily in large concentrations. Going cold turkey on caffeine can lead to headaches as withdrawal and will cause your tolerance to drop somewhat.
If you want to use caffeine as a way to trigger a laxative effect, consider drinking it after a meal rather than before, and keep in mind that it would still take some time for your body to go through the meal and complete digestion. Another way to speed things up (and keep your gut healthy) is to avoid inflammatory foods, maintain a healthy consumption of fiber, and drink lots of water.
Caffeine as a Diuretic
Despite claims to the contrary, caffeine is not an effective diuretic. It does affect the endocrine and digestive systems but speeding up your bladder’s functions isn’t one of those effects. As such, caffeine – when taken in the form of an energy drink of coffee – isn’t going to contribute to dehydration, in case you wondered. This is in no small part due to the fact that coffee is still 99% water in the very least, and drinking coffee counts as hydrating yourself.
Caffeine headaches are another matter entirely. I’ve written an article on this subject, delving into how caffeine can both cause and alleviate headaches depending on the circumstances and situation – but caffeine doesn’t cause headaches due to dehydration.
That being said, don’t source your daily liquids from coffee alone. Be sure to eat enough, drink enough water, and get proper amounts of sleep. Imbalances in any of these three will lead to issues with dehydration, and a cascade of other problems.
What Else Is in Your Coffee?
The way coffee affects digestion doesn’t just depend on the caffeine content in the cup and your individual reaction to said caffeine – it also depends on what else is in the cup. Black coffee is less likely to have a serious effect on you than coffee with cream and/or sugar. If you’re trying to fast longer for certain health benefits, more than a cup of black coffee can spike your insulin. That means anything from two cups of black coffee to a cup of coffee with sugar or creamer. Meanwhile, you may struggle with digestion issues after a cup of coffee because you’re not agreeing physically with the cream or creamer you use. Try drinking black, or switch to a different type of creamer, such as soy.
In closing, it’s highly unlikely that your cup of coffee is negatively affecting your digestion, and regular coffee consumption (around or less than three cups a day) is incredibly unlikely to lead to gastritis or indigestion and is not dehydrating. Taking much higher doses of caffeine can lead to negative effects, especially in tablet form or through extreme energy drinks and novelty coffee products, but the average strong cup of black won’t significantly change the way your body processes food, aside from giving your metabolism a slight boost and promoting gastric peristalsis.
Research has been done to see if coffee has any effect on several other gastric diseases, with no conclusive evidence showing that it does. Aside from gastritis, coffee has been suspected to play a role in peptic ulcers, and stomach cancer. While there are few comprehensive studies and peer-reviewed papers, those that do exist rule coffee out as a significant factor in the development of these diseases. Stressful lifestyles, high BMI, use of alcohol and cigarettes as well as bacterial infection were all much more likely factors.
Myths on the subject of coffee and digestion are not necessarily to be ignored in wholesale. The average person won’t have any trouble enjoying coffee on the regular, but it’s not a good idea to indulge in a lot of coffee when you’re having heart-related issues, are prone to heartburn, or have a pre-existing, often hereditary gastric illness like Crohn’s disease. Furthermore, coffee consumption is a factor in gastro-oesophageal reflux (a form of acid reflux) as well as gastric cardia cancer, the cardia being a small section at the top of the stomach, especially in individuals where coffee does relate to an increase in acid reflux.
Drinking black coffee won’t kill you and quitting likely isn’t going to change much for your health, heartburn or gastric issues if you suffer from a poor diet, an alcohol-heavy lifestyle, or smoke frequently. Avoid foods that disagree with you, and if necessary, consult with a nutritionist to develop a diet best suited to your body as per DNA tests. Modern-day tests exist to determine whether you share sensitivities to certain foods due to your genetic heritage, such as issues dealing with lactose, grains, or certain legumes. Exercise at least twice a week for cardiovascular health, monitor your blood pressure and resting heart rate, and quit smoking. If you’re still struggling with gastric problems, cut caffeine out too and wait and see.