Does Coffee Give You Heartburn? Scientists Discover Why

2010-03-25 07:26

If you cannot imagine starting your day without having a cup of coffee, nearly 20 percent of people can. That’s because for them, coffee causes heartburn and stomach distress, and scientists say they have discovered the reason for the pain.

A team of European investigators recently presented their findings at the 239th National Meeting of the American Chemical Society, where they pointed out that until now, previous research has not established the potential for certain components in coffee to irritate the stomach. Although some coffee manufacturers put their coffee beans through special processes intended to produce so-called “stomach-friendly” coffees, the success of the end results are not clear.

One thing that may occur as a result of these irritant-reducing attempts is that they also lessen the amount of beneficial substances in coffee, which numerous studies have shown to include a reduced risk of heart disease, stroke, Alzheimer’s disease, and diabetes. Stomach-friendly coffees may also lack the taste and aroma appeal of less gastro-friendly brews.

It is difficult to miss the abundance of coffee houses in the United States and around the world, clear indications of how popular coffee is. The NCA’s (National Coffee Association of the USA) 2010 National Coffee Drinking Trends market-research survey shows that coffee consumption has remained unchanged as compared with 2009, indicating that coffee is recession resistant. Daily consumption in 2009 among adults 18 years and older was determined to be 56 percent, while 68 percent reported enjoying the brew within the past week. The NCA also reports that 40 percent of the coffee consumed is gourmet.

Yet an estimated 40 million Americans cannot enjoy coffee at all or only a small amount because they experience heartburn when they do drink it. The new research, conducted by Veronika Somoza, PhD, of the University of Vienna in Austria, and Thomas Hofmann, PhD, of the Technische Universitat Munchen in Germany, believe their study “could lead to a new generation of stomach-friendly brews with the rich taste and aroma of regular coffee.”


The scientists studied the impact of various types of coffee—dark-roast, mild, decaffeinated, regular, and stomach-friendly brews—on cultures of human stomach cells. They found that substances such as caffeine, catechols, and N-alkanoly-5-hydroxytryptamides seem to trigger chemical changes associated with an increased production of acid.

It was the first time such a discovery had been made about these coffee components. Somoza and Hofmann note that a combination of compounds seems to cause the irritating effect and not a single element. They also found that a component called N-methylpyridium (NMP) appears to have a beneficial effect by blocking the ability of stomach cells to produce hydrochloric acid.

Because NMP is not found in raw coffee beans and only appears when the beans are roasted, darker-roasted coffees contain a greater amount of NMP, which means espresso, French roast, and other dark-roasted brews may actually be less irritating to the stomach than less hearty ones. The amount of NMP in any specific coffee can vary depending on the variety of bean and how the coffee is roasted.

“For consumers, coffee is a given, a daily enjoyment,” according to Robert F. Nelson, president and CEO of the National Coffee Association. If Somoza and Hofmann are successful, millions of more people will be able to start their day with a cup or more of coffee without fear of heartburn. They are now experimenting with various varieties of raw coffee beans and roasting methods to see if they can enhance NMP to produce a delicious, stomach-friendly coffee.

American Chemical Society
National Coffee Association



May I suggest testing your brews with and without aeration. I have long felt that coffee like tea and like red wine needs to breathe to reduce a certain amount of tanic taste. Reducing the tanic taste might be more useful. To achieve this aeration test, simply divide the brew into two halves. Pour one part into a cup for tasting and the second part should have several pours back and forth until frothy. Another consideration is the time from first brewed until consumed. If drunk immediately, then the delicate oils of Arabicas have not been damaged due to sitting on heat. Continuing to heat your brew will turn the coffee oils and might contribute to an undesirable feeling in ones stomach. Other factors that might not be so obvious is the possibility for defective beans coming from source that were not processed without tainting. Sometimes the coffee sack containing green coffee gets wet leading to mold or mildew. The beans are then damaged, but an unscrupulous roaster may try to move them by dark roasting the taste to mask the tainted beans which is a very bad thing to do. On another issue, I have long believed that roasters that use super heated air, like the fluid bed roasters, tend to dry out the oils within the coffee bean. Probat roasters have less air flow and may prove to show more NMP within then high air flow roasters. Which takes us to another important aspect of roasting, the rate of climb of the roast. Too fast and the outside burns, too slow and the inside bakes. I wish you luck in trying to organize all these variables.
You mentioned, "They also found that a component called N-methylpyridium (NMP) appears to have a beneficial effect by blocking the ability of stomach cells to produce hydrochloric acid." I understand why someone would think that blocking acid production would be beneficial. However, the research I've done specific to some causes of mental illness and other ailments, points to an inadequate level of hydrochloric acid in the stomach. So I guess it's how you look at the situation...and what your specific health issue is.
Totally agree. There is a lot of research available and opinions vary but the one great conclusion is that there is always a negative effect on the body no matter which coffee you over do it with. In moderation is always key but it is agreed that it's not a healthy choice either way.
Daniel Reid said coffee is alkaline/basic and then causes the stomach to try to return to its original pH by producing acid almost 20 years ago, were these scientist and your editor under a rock?
You may not agree with the findings of this particular group of researchers; however, I have only reported their findings. This does not mean I necessarily agree with them either. In addition, everyone has a unique biochemical makeup, and not everyone responds to coffee in the same way. Thank you for your comments.
I always wondered about this why coffee gives me hurt burn. But the thing is that not all types of coffee gives me heartburn. Some do, others don't. Anyone knows why?
I am not a big coffee or hot tea drinker, a cup a day, but I've noticed heartburn afterward. I don't drink black coffee nor strong dark tea. Basically Maxwell House. No fancy strong brands. I use little and add milk but still get an uncomfortable feeling and rarely finish it. I drink it mainly because of the warm liquid feeling. I actually can get heartburn if I drink orange juice with its acidity. I basically should only drink water which is a bummer - so I wind up dehydrated most of the time. I'm amazed so many feeling feel the same effects but still drink a lot of coffee all day long.
Roberta: Thanks for your comments.I no longer drink coffee either (but love the aroma!) Being dehydrated is not healthful! Just drinking water can be boring, but what about infused waters that you can make yourself? There are two articles on Emaxhealth that I wrote about infused waters. You might also want to try barley water and coconut water. Again, there is information on these waters on this website. Stay hydrated!