The Complicated Relationship Between Coffee and the Stomach

It’s a tale as old as time. You fall in love with the sweet hypnotizing aroma of coffee, only to find that the smooth eye-opening energy-boosting brew leaves you with the unwanted sensation of heartburn, pain, and an upset stomach. 

So, what is the complicated relationship between coffee and the stomach???

Coffee is one of the most popular beverages in the world. Why are some people able to enjoy it without any stomach issues while others can’t make it through a single cup without unsavory side effects? 

Well, the answer might surprise you.

Many believe it’s caffeine, while others say it’s acid, but what if the answer is more complicated?

Here we will dive into the complex relationship between coffee and the stomach and what the real cause of stomach upset is. 

Let’s start with the science behind caffeine. 

Caffeine

Caffeine is a naturally occurring stimulant that affects the adenosine receptors in the brain. Long story short, the stimulation of the A2a receptors are responsible for the sensation of wakefulness that comes along with your cup of coffee. 

Caffeine is the main reason millions of people drink it every day. Sometimes three times a day. 

But consuming caffeine in moderation alone is not all that bad. On the contrary, there are many benefits. 

Caffeine studies show it may reduce headache pain and improve neurocognitive decline. It has also been linked to a decrease in all-cause mortality, meaning all the older people drinking 4-5 cups of black coffee a day may live longer than their non-coffee drinking counterparts (Evans, 2023). 

Caffeine has also been shown to be beneficial for the gut. Of course, it does depend on the source of the caffeine. Caffeine from a cup of coffee may improve the gut health in the stomach, while caffeine from a soda or other sugary beverage may have harmful effects on gut health. In other words, the natural coffee source may improve your gut health by getting rid of the bad bacteria and adding more good bacteria. 

Studies reveal that caffeine can increase the mobility of the stomach which in turn causes an increase in bowel movements. This is not a bad thing! About 16 out of 100 adults suffer from or complain of constipation. The increased mobility of the stomach can lead to a relief of constipation, improving stomach discomfort, not causing it (Nehlig, 2022). 

So, if you are consuming your caffeine from a high quality, organic coffee, then the caffeine shouldn’t be causing any stomach upset. 

Acid

Now, let’s talk about acid.

There are two ways to look at acid. One is the pH level of the coffee, and the other is the type of acid you are consuming. 

Let’s start with the pH level.  

When talking about a pH level we are looking at how acidic or alkaline something is. The pH scale ranges from 0-14. Zero represents a high acid content (such as hydrochloric acid), and 14 represents an alkaline content (such as drain cleaner). Both extreme ends are dangerous and harmful to the body. 

Water is neutral in the middle, with a pH level of 7. Lemon juice is on the acidic side with a pH of 2. Baking soda is more alkaline with a pH of 8.  Coffee typically lands on the acidic side ranging from 4.85 to 5.13 (Rao, 2018). 

 

But does the acidity of coffee cause heartburn and other stomach ailments?

Not necessarily.

The stomach is designed to not only digest food but to also be the first line of defense against illness. To function correctly, the stomach’s pH level must be on the acidic side. It lands between a 1 and 2 on the pH scale, so it is already acidic. 

When a person complains of heartburn, it is not because there is too much acid in the stomach. When heartburn occurs, acid moves into the esophagus, which connects the throat to the stomach. A pH level under four can cause damage and irritation to the esophagus, resulting in heartburn. (Kim, 2010). 

So if coffee’s pH level does not cause heartburn, what does?

 

What about the type of acid? 

Chlorogenic acid is a type of acid found in coffee beans. In a literature review of the effects of coffee on the gastrointestinal system, it was discovered that chlorogenic acid may not decrease the pH level of the stomach but could increase the stomach acid production, causing more acid in the stomach (Nehlig, 2017). For someone already at risk for heartburn, this could cause an increase in heartburn symptoms. 

Therefore, it may not be the acidity level of the coffee causing stomach issues but the chlorogenic acid it contains. Fortunately, there is a way to combat chlorogenic acid and create a cup of coffee that helps inhibit the production of stomach acid instead of increasing it. 

How is this possible, you ask?

It’s all about roasting.

Now that we have already talked about coffee’s pH level, the acid type, and how these things may affect a person’s stomach, let’s talk about how you can increase your chances of enjoying your morning coffee without stomach issues. 

Roasting 

Roasting the coffee bean is the most important part of getting that smooth, delicious coffee flavor. There are five stages of roasting. Coffee beans start out as small, tasteless, and moist green beans filled with chlorogenic acid and a low pH. It is through the roasting phase that the chlorogenic acid burns off and pH levels increase, creating the delicious, flavorful coffee you love. 

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Here are the stages:

1.​Drying- simply removing the moisture from the bean. 

2.​Yellowing- beans start to turn yellow and have a rice-like scent.

3.​First Crack- as the beans heat up, the pressure inside the bean increases until it starts to pop and crack. It is here that the flavor starts to develop. From this point on, the roasting can stop at any time. 

4.​Roast Development- The longer the roast, the more chlorogenic acid burns off, causing the pH level to increase, creating a less acidic coffee. Another amazing reaction in this stage is the increase in N-methylpyridinium (NMP) which studies show may decrease production of stomach acid. In other words, the longer the coffee roasts, the less acidic it becomes, and the less likely it is to cause an increase in gastric acids in the stomach. 

5.​Second Crack- Not every coffee bean makes it to the second crack. At this point, the bean is at risk of catching fire, which is dangerous and can lead to an extremely bitter and even burnt coffee. 
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It is in the fourth stage of roasting that the different types of roast and flavors are created, all depending on the length of time and temperature that roasting occurs. The longer the roast, the gentler the coffee is on the stomach, but the longer the roast, the more bitter the coffee. This is why a darker roast, even though stronger and bolder in flavor, is gentler on the stomach.    

Why do we measure the pH?  

The pH tells us the acidity level of the brew. Since many people report having indigestion or stomach aches associated with the acidity in coffee, here at Smart Owl we are dedicated to providing a cleaner, healthier coffee experience, and we felt it was important to utilize lower acid coffees for all of our blends.

While coffees typically have a pH of between 4.5-5.5 because of how they are grown, processed, and roasted, all Smart Owl Coffees, when brewed by the National Coffee Association standards, will yield a pH of 6.0 or higher.

We are able to achieve this by selecting specially grown beans from boutique farms that are able to cater to our specific needs. We also use a slow roasting process that burns off excess chlorogenic acid, resulting in super smooth, low-acid coffee :)

Try all 5 of Smart Owl Coffee’s Usda organic, supplement infused blends. Doctor formulated to help optimize your wellness with each cup.

References

Evans, J., Richards, J.R., & Battisti, A. S. (2023). Caffeine. StatPearls. StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK519490/#_NBK519490_pubdet_ 

Kim G. H. (2010). How to Interpret Ambulatory 24 hrEsophageal pH Monitoring. Journal of neurogastroenterology and motility, 16(2), 207–210. https://doi.org/10.5056/jnm.2010.16.2.207

Nehlig A. (2022). Effects of Coffee on the Gastro-Intestinal Tract: A Narrative Review and Literature Update. Nutrients, 14(2), 399. https://doi.org/10.3390/nu14020399

Rao, N. Z. & Fuller, M. (2018). Acidity and antioxidant activity of cold brew coffee. Scientific Reports. https://www.nature.com/articles/s41598-018-34392-w#:~:text=This%20work%20found%20the%20pH,ranging%20between%204.85%20to%205.13