Dr. Day is a cardiologist/electrophysiologist at the Intermountain Medical Center Heart Institute in Salt Lake City, Utah. He graduated from Johns Hopkins Medical School and completed his residency and fellowships in cardiology and electrophysiology at Stanford University. He is the former president of the Heart Rhythm Society and currently serves as the president of the Utah chapter of the American College of Cardiology.
Is Caffeine Safe for the Heart?
New research reports that caffeine does not cause an irregular heart beat, palpitations, or heart arrhythmias. Can we really believe the results of this new study? Read on to see my answer to the question, is caffeine safe for the heart?
Mark was a 46 year old man who came to see me for palpitations and a rapid heart beat. Mark was tired all of the time. The only thing that could get him through the long work day was Red Bull and Monster energy drinks.
He typically started off the day with a Red Bull. In the afternoon, when energy levels were at the lowest, he would switch to Monster. Sometimes, if he was really tired, he might add in a third energy drink or even a cup of coffee.
To identify the cause of his palpitations and rapid heart beat, I had him wear a heart monitor. After just a few days it was obvious what was going on.
His palpitations clearly correlated with premature heart beats arising from his ventricles or PVCs. The rapid heart beat coincided to short episodes of a heart arrhythmia called atrial fibrillation.
Fortunately, Mark’s stress echocardiogram and other tests were completely normal.
Knowing about the reported possible heart dangers of energy drinks, I asked him to stop the energy drinks. I also encouraged him to eat healthier, exercise every day, and make sleep a priority.
When he came back to see me a month later, he reported that his energy levels were much better. His symptoms were also completely gone.
Initially, I suspected it was the eliminating the caffeine from the energy drinks that did the trick. I was surprised to find out that while he no longer drank energy drinks, he was now eating dark chocolate on most days. With this new information, it became clear to me that perhaps caffeine was not the cause of his heart troubles.
Latest Study on Caffeine and Abnormal Heart Rhythms
This past week, a new study was published by my colleagues at the University of California, San Francisco (UCSF) on the effects of caffeine to the heart’s rhythm. As might be expected, as soon as this study was published, headlines around the world reported “Caffeine May Not Cause Palpitations.”
To measure the effect of coffee, tea, and chocolate on the heart, participants also wore heart monitors to record every heart beat. When UCSF cardiologists reviewed their heart monitors, they found no correlation between the number of irregular heart beats and caffeine intake. In other words, regardless of their caffeine intake, it did not seem to affect how many premature atrial contractions (PACs) or premature ventricular contractions (PVCs) study participants had.
Limitations of this Caffeine Arrhythmia Study
Does this study mean that people who suffer from heart arrhythmias can have all the caffeine they want? Not so fast. This study leaves many questions unasnwered. In my opinion, there are three big limitations of this study.
1. This was an observational study.
As an observational study we can’t conclusively say that caffeine from coffee, tea, or chocolate doesn’t cause heart arrhythmias. All we can say is that, for whatever reason, the amount of caffeine consumed from coffee, tea, and chocolate in this study, did not seem to affect the number of irregular heart beats.
There could be other reasons why these study participants were not affected by caffeine. Perhaps these people practiced mindfulness techniques, like meditation or yoga, to control stress and keep irregular heart beats at bay with increasing doses of caffeine.
2. This study did not include caffeine from other sources.
Study participants were only asked about coffee, tea, and chocolate consumption. They were not asked about caffeine from other sources. For example, researchers had no idea if study participants were also drinking Diet Coke or Red Bull.
3. This study did not compare fast versus slow caffeine metabolizers.
It is possible that most of the study participants were fast caffeine metabolizers. For fast caffeine metabolizers, caffeine consumption has little affect on the heart.
Fast vs. Slow Caffeine Metabolizers
Does caffeine make it hard for you to sleep at night? If so, then chances are that you are part of the 50% of people who have a genetic variant to your CYP1A2 gene.
Variations in the CYPA12 gene can cause you to metabolize caffeine more slowly. Indeed, based on your genetics, there can be up to a 40-fold difference in how fast caffeine is metabolized in your body.
These genetic differences may explain why some studies report that caffeine may be dangerous to your heart and other studies, like the one discussed in this artice, report that caffeine is safe. Indeed, other studies report that caffeine slow metabolizers can have up to a 64% increased risk of a heart attack depending on their caffeine dose.
Fortunately, less than 100 mg/day appears to be safe, even for caffeine slow metabolizers. How much is 100 mg of caffeine? A 100 mg dose of caffeine is approximately the equivalent of one cup of coffee, two cups of tea, three 12-ounce cans of soda pop, or four ounces of dark chocolate.
Why does medical science seem to be “flip flopping” on issues like coffee and caffeine? This is likely because we have not taken into account genetic differences. Just as everyone responds differently to medications, everyone responds differently to caffeine.
When it comes to caffeine metabolism, I am a slow metabolizer. Fortunately, dark chocolate does not cause palpitations or arrhythmias for me. While I love my dark chocolate, as a slow caffeine metabolizer, I must eat it first thing in the morning or I will have troubles sleeping at night.
The Big Picture
In the big picture of things, if you suffer from palpitations, arrhythmias, or heart problems should you or shouldn’t you consume caffeine? Fortunately, this study suggests that if your caffeine source is coffee, tea, or chocolate you may be just fine.
One important thing to remember is that this study was just an average of 1,388 people. I’m sure that of these 1,388 people, there were some whose heart’s were very sensitive to caffeine. Perhaps these were the caffeine slow metabolizers?
While you could certainly have your genes tested to find out, as I described in a previous blog, perhaps an easier solution would be to just monitor how caffeine affects your body. If caffeine causes palpitations or heart arrhythmias it would be best to avoid caffeine. In contrast, if it doesn’t seem to bother you then it is probably OK unless your doctor tells you otherwise.
If you have heart problems or insomnia, try cutting out caffeine, or even setting a caffeine curfew of say 12 pm in the afternoon, to see if it makes a difference. Perhaps you are like me in that caffeine is fine first thing in the morning.
How does caffeine affect you? Please leave your comments below. Also, if you have any questions about this article, please leave your questions below. I will try to answer every question.
Disclaimer Policy: This website is intended to give general information and does not provide medical advice. This website does not create a doctor-patient relationship between you and Dr. John Day. If you have a medical problem, immediately contact your healthcare provider. Information on this website is not intended to diagnose or treat any condition. Dr. John Day is not responsible for any losses, damages or claims that may result from your medical decisions.