What’s the Story with Low Acid Coffee?

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Why are people asking for low acid coffee?

There is strong evidence that coffee triggers stomach discomfort in some people.  20 years ago I was among them!   But since roasting and drinking Birds and Beans coffee, I have had no problems.  So what could be going on? (jump to spoiler)

What is low acid coffee

There are 2 totally unrelated meanings of acidity with respect to coffee. The Specialty Coffee Association defines acidity as: “Acidity is often described as “brightness” when favorable or “sour” when unfavorable. At its best, acidity contributes to a coffee’s liveliness, sweetness, and fresh- fruit character and is almost immediately experienced and evaluated when the coffee is first slurped into the mouth.”  So, in coffee cupping (that is, formal coffee tasting), acidity is a quality that has nothing to do with chemical acidity or pH. It simply describes a tasting experience.

More recently, coffee brands claim their coffees are “low acid”.   They mean that the coffee is lower in chemical acidity… that they have a lower pH.

Many online articles conflate the chemical pH with the SCA cupping quality making it very difficult to navigate claims made by coffee brands.  Nevertheless, lets try!

What Factors are Said to Impact Coffee pH?

OK, so with respect to stomach discomfort, low acid coffee brands are referring to lower pH in brewed coffee.  Some brands are measuring the pH of brewed coffee, but most are relying on other factors that are said to impact the pH of a cup of coffee. The factors I found in my investigation are:

  • caffeine,
  • darker roasting,
  • faster roasting,
  • Robusta beans vs Arabica, 
  • beans sourced from Central America, 
  • beans sourced from Indonesia, specifically Sumatra

But do these factors actually result in coffee with lower in pH?  And if so, is it the pH that is causing discomfort?

Do These Factors Really Impact Coffee's pH?

In my investigation, I have seen little evidence that these factors impact the pH of a cup of coffee.  In fact I have seen clues that indicate that the SCA definition of acidity has been conflated with pH!  

The SCA description of acidity with respect to coffee cupping continues to say: “Coffees expected to be high in Acidity, such as a Kenya coffee, or coffees expected to be low in Acidity, such as a Sumatra coffee […]”.  Clearly this is where the association of low acidity in Sumatran coffees originated… and it has nothing to do with pH.

Scientific papers (such as this one and this one) that suggest a link between any of these factors with low acid in coffee have not been confirmed in followup studies.

It is clear that coffee triggers discomfort, but is it because of low-acid coffee claims?  So far, only the coffees actually lab tested would hold up.  So lets look more into acidic foods in general.

Does Higher pH in Coffee Increase Stomach Discomfort?

Let’s look at what is known about gastric acid.  Gastric acid is strongly acidic with a pH between 1 and 2.  It helps breakdown food in the stomach to allow absorption of nutrients.

Healthline says that when stomach acid levels become high, various symptoms arise including: nausea or vomiting, bloating, abdominal discomfort that may worsen on an empty stomach, diarrhea, heartburn, decreased appetite, unexplained weight loss.

In some people, coffee seems to trigger high production of gastric acid that creates discomfort know as heartburn, GERD and acid reflux.  But is that because the coffee itself is acidic? 

There does not appear to be any evidence to support that.  There are a few suggestions for future studies, but nothing remotely definitive.

It seems that, for those of us affected, coffee is triggering our bodies to over produce gastric acid but why that happens has not been remotely linked with the pH of the coffee itself.  The only common factor across several studies may be caffeine.

My Speculation based on my experience

Given the complexity of the problem and the inconclusiveness of the science, I think that the National Institute of Health has the best suggestion: “avoiding foods and drinks that make your symptoms worse“.  So in that spirit I am going to share my speculation with you.

I asked myself “Why does Birds and Beans coffee never trigger my acid reflux when previously is was a problem for me?  What is different about our coffee?”

Well there are many things that are different about our coffee, but the one that jumps out at me as most likely is that we drink our coffee within weeks of roasting it. As a biochemistry grad, it seems to me plausible, even likely, that when the coffee’s delicious flavourful oils oxidize into bitter rancid molecules the result could easily be responsible for triggering overproduction of gastric acid.  Since I always drink our coffee freshly roasted, it doesn’t trigger the problem in me.  

We have received many similar anecdotal reports from customers.  We have even had a few who claim that our freshly roasted coffee reduces pain from inflamed joints!   


We could just follow the coffee marketer’s trend of identifying low acid coffees.  If we did we would point out that all our beans are Arabica.  We have several dark roasted Central American coffees to choose from like Nicaragua Wood Thrush and Honduras Howler Monkey Pitch Black.  You can choose a decaf to see if the caffeine is the problem. So these tick the low-acid boxes.

But assuming I’m right, and it is the freshness of the coffee that is most important, I encourage you to try any of our coffees that you find appealing.  We guarantee the coffee is roasted within a week, and its usually roasted the day we ship it! Let us know what happens!

Meanwhile I’ll keep monitoring for new studies… hopefully someone will do one that looks at coffee freshness.

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