There are two camps of coffee consumers – slow metabolizers and fast metabolizers. The rate at which you metabolize caffeine is a determining factor in your reaction towards coffee. Are you energized and euphoric after drinking a cup or do you feel wired and tired? In this post, I’ll be shedding some light on the link between coffee and genetics. You’ll also learn how to find out if you’re a fast or slow metabolizer.
Facts About Caffeine
If you’ve read studies on the effects of coffee you know how controversial it is. Caffeine is without a doubt one of the most popular stimulants used worldwide. A cup of coffee in the morning is a non-negotiable for millions of people due to its effect on the central nervous system. Caffeine is used for its ability to boost energy and alertness, elevate mood, reduce drowsiness, and even increase athletic ability.
Caffeine exerts its effects by passing quickly into the brain following absorption, reaching a peak blood level within 30 minutes to an hour. The half-life of caffeine ranges from three to five hours, which is the period of time it takes the body to eliminate half the amount of caffeine that was taken in. The remainder can stay in the body much longer. Cutting out caffeine cold turkey can cause headaches due to the impact it has on the blood vessels in the brain.
Coffee, tea, and cola drinks are undoubtedly the most heavily consumed caffeinated beverages. Here’s an equation that will give you an idea how the caffeine content compares between the three: roughly 2 cups of tea = 1 cup of coffee / 2 cola drinks = 1 cup of tea. The type of tea and coffee used, along with the brewing times, can factor significantly into this equation.
One cup of coffee contains 100 to 200 milligrams of caffeine. Black tea has more caffeine than green tea, which has more caffeine than white tea. The Mayo Clinic has deemed 400 milligrams of caffeine a day to be safe for an average healthy adult. This amount, however is going to be highly individualized, depending on several factors, which I’ll cover below.
Your individual genotype may play a pivotal role in how you metabolize caffeine, and therefore how coffee affects your physiology. Caffeine stays in the bloodstream longer in people who are slow metabolizers of caffeine, giving it more time to exert its stimulating effects. The rate at which you metabolize caffeine can be a determining factor in whether coffee is beneficial or detrimental to your health. Half the population has a CYP1A2 variant.
For instance, slow metabolizers are at increased risk of developing high blood pressure, cardiovascular disease, and impaired fasting glucose, notably in people who already have hypertension. Keep in mind, there are many epigenetic factors outside the genome, that can affect how a person reacts to caffeine.
Lifestyle habits, including diet, the amount of sleep and exercise someone gets, how they deal with stress, and whether they smoke or take hormonal birth control all impact caffeine metabolism. Even the gut microbiome is part of the picture. Caffeine can cause anxiety and insomnia in slow metabolizers, rather than the boost in energy and mental clarity that fast metabolizers experience.
Symptoms are likely dose-related, so cutting back or in some cases eliminating caffeine altogether, may be the logical answer for reducing symptoms, and preventing possible health implications associated with caffeine. Monitoring caffeine intake is key. Another variable that could be responsible for negative symptoms after drinking coffee is sensitivities to substances within the coffee itself.
Fast metabolizers process caffeine more quickly than do slow metabolizers. This limits the stimulating effects of caffeine. Unlike slow metabolizers, there is no correlation between caffeine and cardiovascular risk for those who metabolize caffeine more quickly. Fast metabolizers have more leeway in the amount of coffee they can consume without experiencing negative repercussions.
Remember though, slow and fast metabolizers fall on a continuum rather than having an absolute value, meaning you could be a particularly slow metabolizer or more of a moderate one. A moderate metabolizer may very well experience different reactions from drinking coffee than would a very slow metabolizer. Likewise, it’s possible to be a significantly fast metabolizer of caffeine or one that falls more on the slower end of the spectrum.
The faster the rate of caffeine metabolism, the less pronounced the stimulating effects of caffeine will be because it leaves the system more rapidly. This is why coffee can give slow metabolizers the jitters and ramp up anxiety. Fast metabolizers, on the other hand, can metabolize caffeine up to four times as quickly, and since caffeine doesn’t stay in their systems as long, it’s less likely to cause symptoms. Fast metabolizers are the ones who feel energetic, mentally alert, and happy after their morning coffee.
Drinking coffee may have protective effects for fast metabolizers when it comes to cancer. Coffee consumption in fast metabolizers has been associated with a significant decrease in breast cancer risk in women who carry the BRCA1 mutation. I find it interesting that the CYP1A2 gene (see below) can be both inhibited or stimulated by certain medications. For example, fluoroquinolones are metabolized by the CYP1A2 enzyme, which can further inhibit the breakdown of caffeine, thereby accentuating its action.
The Link Between Coffee and Genetics
Caffeine is metabolized in the liver by an enzyme that encodes for the CYP1A2 gene. Cytochrome P450 1A2, which is abbreviated CYP1A2, is part of the oxidase system responsible for metabolizing xenobiotics, drugs, and chemicals, including caffeine. The CYP1A2 enzyme is encoded by the CYP1A2 gene in humans. The particular variant within the genetic allele is what determines the rate of caffeine metabolism.
Are you curious to whether you’re a slow or fast metabolizer of caffeine? Consider doing genetic testing if you’d like to find out. Visit 23andMe or SmartDNA to get a test kit sent to your house. A simple saliva swab is all that’s required. Include the sample in the kit, send it back to the company, and wait for your results. The process is very straightforward.
Once you get your results back, you’ll need to run the raw data through a program in order to get your genetic SNPS. LiveWello or Genetic Genie are both good options. If you already have your raw data, but don’t know what markers to look for: go to 23andme.com, “your account,” and “browse raw data.”
In the search bar, enter “CYP1A2,” and then look for the rs762551 SNP. To the right of the SNP you’ll see your variant. It will either be AC, CC, or AA. AC and CC are the slow-metabolizer variants, with CC being slower than AC. The AA variant designates you as a fast metabolizer.
If genetic testing is prohibitive to you at this time, you can always wean yourself off caffeine – do it gradually – for at least a month. Then re-introduce it back into your diet and note your reactions based on the information you’ve learned in this article.
I hope this post has provided some valuable insights for you in regard to your particular reactions to caffeine, and has put into perspective why coffee can be both good and bad.
The link between genetics and caffeine metabolism is quite fascinating, and underscores why there is no definitive answer to the question: “Is coffee good or bad?” We each have to answer that question for ourselves….
What do you think? Are you a fast or slow metabolizer? Let me know in the comments:)
(1) MedlinePlus: Caffeine in the diet
(2) Sleep Education: Sleep and Caffeine
(3) The Guardian: Caffeine compared: from coke and coffee to aspirin and chocolate
(4) NCBI: The Role of Genetics in Moderating the Inter-Individual Differences in the Ergogenicity of Caffeine
(5) PubMed: Coffee, CYP1A2 genotype, and risk of myocardial infarction
(6) PubMed.gov: Association of coffee consumption and CYP1A2 polymorphism with risk of impaired fasting glucose in hypertensive patient
(7) Pathway Genomics: The Genetics Behind Your Caffeine Consumption
(8) Molecular Psychiatry: Genome-wide association analysis of coffee drinking suggests association with CYP1A1/CYP1A2 and NRCAM
(9) SNPedia: CYP1A2
(10) NCBI: The CYP1A2 genotype modifies the association between coffee consumption and breast cancer risk among BRCA1 mutation carriers
Disclaimer: This article is strictly for informational purposes only and is not intended to be medical advice. Please be diligent and always do your own research in regard to any material I present on this site. I claim no responsibility for any distress, whether it be physical or emotional, that may occur as a result of the information you obtain from my blog.