In 1453, Turks brewed the first cup of coffee from the seeds of the coffee plant.1 The hot, caffeinated beverage eventually spread to every country in the world.
Many people say they can’t function without their daily intake of java. (That’s probably why there’s a Starbucks on every corner!) An estimated 54 percent of adults living in the United States drink coffee every day.2 You might even be drinking a cup as you read this. But have you ever stopped to think about what coffee is doing to your digestive health?
Here are five ways coffee is interfering with your digestion. Consider these facts before pouring that next cup:
1. Coffee Increases Stomach Acid Production
Drinking coffee can cause your stomach to produce too much acid, and it’s not just the caffeine. A German study found that regular and decaf coffee both caused the stomach to produce excess acid.3 Having too much acid can irritate your stomach, particularly if you drink coffee when your stomach is empty.
If you can’t drink coffee – or as much coffee as you’d like – because of stomach irritation, you’re not alone. An estimated 40 million people in the United States are “coffee sensitive.” However, there is one silver lining: Researchers have found that dark-roasted coffee varieties, including espresso and French roast, cause less acid production and may be easier to stomach for some people.4
2. Coffee Limits Your Ability to Absorb Minerals
The caffeine present in coffee has been found to limit your body’s ability to absorb some minerals, particularly iron and calcium.5 A 1992 study on postmenopausal women with osteoporosis found that more than 1000 ml of coffee per day could cause a loss of 1.6 millimoles (mmol) of calcium.6 Another study showed that coffee limited iron absorption by 39 percent when it was consumed with an iron-rich meal.7
Not being able to properly digest these essential minerals leaves your body at risk for several health problems. An iron deficiency can cause anemia, a condition with symptoms of fatigue, weakness, and headaches.8 A calcium deficiency can lead to bone health problems, including osteoporosis.9
3. Coffee Promotes Gastroesophageal Reflux
Gastroesophageal Reflux Disease (GERD) is a condition that occurs when stomach contents leak into the esophagus.10 The most common symptoms of GERD are frequent heartburn and nausea after eating. Coffee has been found to irritate this condition, particularly for those already at risk.11 GERD can happen to anyone, but people who smoke or who are obese are more likely to be affected. Doctors encourage patients at risk for GERD or who already have the condition to avoid coffee.
4. Coffee Irritates Your Bladder
The caffeine present in coffee can wreak havoc on your bladder. Caffeine has been found to greatly increase urine production, and can even cause bladder spasms.12 People who have urinary problems, such as overactive bladder, should not drink coffee or other caffeinated drinks.13 According to a study performed at the University of Alabama at Birmingham, men who drink more than two cups of caffeinated coffee per day are more likely to experience urinary incontinence.14
5. Coffee Stimulates Colonic Motor Activity
Your colon is the part of your digestive system that focuses on waste. Waste products are stored in the colon before being pushed out through the rectum. Coffee has been found to stimulate your colon, causing you to void waste products quickly. A study at the Yokohama City University School of Medicine in Japan has shown that drinking coffee causes rapid gastric emptying.15 Another study at the University of Iowa College of Medicine found that the impact of coffee on your colon is similar to that of eating a meal, and 60 percent stronger than water.16
What’s bad about rapid gastric emptying? For one thing, it can often cause stool problems, such as diarrhea. Also, rapid gastric emptying can cause food to be expelled as waste before your body has finished digesting it.
What About the Positive Effects of Coffee?
Drinking coffee does have some positive effects on your gut. A 2009 Swiss study found that coffee diversifies your gut bacteria.17 Having diverse gut bacteria is beneficial, because different bacteria form colonies to fight many types of diseases and health problems.18 Coffee has also been shown to contain a small amount of fiber, which can aid digestion.19 However, both of these positive impacts could more readily be achieved by eating a variety of fruits and vegetables.
How Much Coffee is Safe?
People with health issues, such as acid reflux, Crohn’s disease, IBS, heart problems or anxiety should not drink coffee. Additionally, if you find your stomach is irritated by coffee, it’s best to abstain from drinking it. If you have health concerns, ask your doctor if coffee is okay for you. For healthy people, limit consumption to less than 400 mg of caffeinated beverages per day.20
Coffee is a mainstay in modern culture. But if you have problems with your digestion, try giving it up or significantly cutting back on how much you drink. Many people who do this find that their health improves, and they don’t want to go back to drinking their daily cup(s) of joe.
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14. PhD, Catharine. “Coffee Drinking Tied To Urinary Incontinence In Men”. Medical News Today. N.p., 2013. Web. 23 Feb. 2017.
15. Akimoto K, et al. “Does Postprandial Coffee Intake Enhance Gastric Emptying?: A Crossover Study Using Continuous Real Time 13C Breath Test (Breathid System). – Pubmed – NCBI”. Ncbi.nlm.nih.gov. N.p., 2009. Web. 23 Feb. 2017.
16. Rao SS, et al. “Is Coffee A Colonic Stimulant? – Pubmed – NCBI”. Ncbi.nlm.nih.gov. N.p., 1998. Web. 23 Feb. 2017.
17. Jaquet M, et al. “Impact Of Coffee Consumption On The Gut Microbiota: A Human Volunteer Study. – Pubmed – NCBI”. Ncbi.nlm.nih.gov. N.p., 2009. Web. 23 Feb. 2017.
18. “Seven Foods To Supercharge Your Gut Bacteria”. The Physicians Committee. N.p., 2017. Web. 23 Feb. 2017.
19. Raloff, Janet. “A Gut Feeling About Coffee”. Science News. N.p., 2007. Web. 23 Feb. 2017.
20. “Caffeine: How Much Is Too Much? – Mayo Clinic”. Mayo Clinic. N.p., 2017. Web. 23 Feb. 2017.
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