Do you love your morning coffee…or 3?  Or do you get the jitters or insomnia just thinking about a small cup?  Turns out, your ability to tolerate caffeine isn’t just in your stomach, it starts in your genes, and can even have an impact on your heart attack risk.

First, the technical information.

The gene named CYP1A2 (cytochrome P450) is responsible for the production of a variety of enzymes that break down many substances in our food, in our drinks, and even in the air we breathe.  CYP1A2 itself is responsible for the metabolism of caffeine, and has a role in the metabolism and detoxification of many environmental substances and pharmaceuticals, such as acetaminophen and cigarette smoke.  There are a variety of ways to interact with the enzymes produced from this gene, and certain dietary interventions can either stimulate greater enzyme activity or inhibit it.

When it comes to caffeine tolerance, the CYP1A2 enzyme is in control.  About 40% of the population can be classified as Fast Metabolizers. These lucky folks have a variant of the gene that allows them to burn up caffeine two to four times as fast as the rest of us.  Fast metabolizers have two copies of the gene allele that is efficient at detoxifying caffeine. If you are a fast metabolizer, this doesn’t necessarily mean you DO drink more coffee than others, but it does mean that the caffeine affects you for a shorter amount of time, and is circulated out of your bloodstream faster.

Now, on to the juicy bits.

For fast metabolizers, your genes have given you some bonus points.  It means not only that you metabolize caffeine faster, it means that your body is better able to tolerate the substance.  Excess caffeine has been linked with an increased risk of heart attacks. So, if the compound leaves your system faster, then your risk is lowered. Caffeine acts as an antioxidant, fighting inflammation, lowering blood pressure, and regulating heart rhythm. I covered the many health benefits it confers in a previous blog post. If you’re a fast metabolizer, the current standard recommendation is that up to three cups a day is considered safe for you to consume, though some reports say up to five is just fine.

Those who are considered slow metabolizers, who either have both copies of the slower type of CYP1A2 gene, or who have one copy that is fast and one that is slow, have less tolerance overall, and there is no difference if you have either of these gene combinations: one slow variant means you’re a slow metabolizer.  People who are slow metabolizers tend to not be able to sleep well if they have caffeinated drinks after noon, and some don’t feel well at all after drinking just part of one cup.

They also have a notably higher risk of developing cardiovascular problems with caffeine consumption.  The risk of first and repeated heart attacks as well as hypertension is significantly greater for coffee drinkers who are slow metabolizers.  This means that, if you’re a slow metabolizer, drinking coffee or other caffeinated drinks is a health risk all on it’s own.

Since caffeine stays in circulation so much longer, it essentially acts like a free radical, which is the opposite of an antioxidant: it causes harm instead of providing benefits.  For those of you who are slow metabolizers, sticking to just one cup of coffee a day is more than enough, and you may even want to skip it entirely.

Finding out if you are a fast or slow metabolizer is one painless test away.  All it takes is some saliva and about two weeks to get your results back, and we can see if you can keep drinking your regular latte, or if you should be switching to decaf. Find out more about what a nutrigenomics test kit can do for you here. It can tell you SO MUCH MORE than just how much caffeine you can tolerate. Get in touch on to find out more about the DNA Nutrition Program.

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El-Sohemy, A., Cornelis, M., Kabagambe, E. and Campos, H. (2017). Coffee, CYP1A2 genotype and risk of myocardial infarction. National Center for Biotechnology Information, U.S. National Library of Medicine. Available at:

Faber MS, e. (2005). Assessment of CYP1A2 activity in clinical practice: why, how, and when? – PubMed – NCBI. [online] Available at: