Well, it depends on your genes.

Coffee

Oh coffee. You love it, you hate it. You can’t go a day without it, or you maybe even need 2 or 3 cups of it to get through your morning.  

Let’s explore some fun facts that you may not have known about this precious source of caffeine! 

1. Did you know that coffee was discovered when a herder noticed that his goat had eaten some coffee beans and became a little more energetic than normal? Well now you do [1].
2. After oil, coffee is the most traded commodity around the world! [1]
3. There are different species within the coffee plant family, however only 2 of them, Coffea arabica and C. canephora, supply all the world’s consumption [2]. 

But how do coffee and our genetics influence one another?

The key is the caffeine within coffee. 

Caffeine influences our biological systems when it is metabolized by our body. Cytochrome P450 is an enzyme that can be found in our liver and works to metabolize caffeine. 

CYP1A2 is a gene that controls Cytochrome P450 enzymes. Different mutations in this gene thereby influence the functionality of Cytochrome P450 enzymes. For instance, if you are A/A homozygous for the CYP1A2 gene, you would be considered a fast metabolizer of caffeine. If you are A/C heterozygous for the CYP1A2 gene, you would be considered a normal metabolizer. This is the most commonly found gene mutation. Finally, if you are a  C/C homozygous for the CYP1A2 gene, you would be considered a slow metabolizer of caffeine [3]. 

So, how can you tell if you are a fast, normal, or slow metabolizer of caffeine? Unfortunately, your physical reactions aren’t enough to tell. You’ll need to have a genetic test with genome sequencing to learn which CYP1A2 gene mutation you have. 

What does this mean about your health? 

Many debates have argued over whether coffee is beneficial or harmful to one’s health. The reason for this constant back and forth may have to do with the fact that these studies didn’t consider their participants’ CYP1A2 gene mutations. Now that we know about this crucial genetic difference, future studies might have more definitive conclusions.

For instance, studies that have considered CYP1A2 gene mutations found that when individuals consumed over 200mg of caffeine per day, those with the C/C homozygous mutation (aka slow caffeine metabolizers) presented a larger risk for hypertension and nonfatal myocardial infarction compared to individuals with the A/A homozygous mutation (aka fast caffeine metabolizers). Thus, the data showed that high amounts of caffeine intake was more harmful to slow caffeine metabolizers. For this reason, the recommended daily intake of caffeine for slow caffeine metabolizers is less than 200mg per day [3]. 

What about your athletic performance?

Does caffeine have an effect on your workouts?

Check out what this 2018 study found in male athletes. The male athletes were genotyped and given various amounts of caffeine before completing a timed-trial on a stationary bike [4]. 

They found that there was a strong interaction between one’s CYP1A2 gene mutation, amount of caffeine, and athletic performance. For male athletes who were C/C homozygous (aka slow caffeine metabolizers), those who took 4 mg/kg of caffeine before the timed-trial showed higher times, meaning that they did significantly worse than those who did not take any caffeine at all. However, vice versa results were found for A/A homozygous individuals (aka fast caffeine metabolizers): Those who took 4 mg/kg of caffeine had lower timed-trial times, therefore performing significantly better than those who had no caffeine at all [4]. 

Thus, this study demonstrated how one’s CYP1A2 gene mutation can greatly determine the effect caffeine will have on one’s athletic performance [4]. 

So, the next time you’re brewing up your favorite cup of joe, or standing in line at Starbucks, think about how your very own genetics may affect how that caffeine will hit you. 

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References:

1. Eldridge, A. (Invalid Date). Know Your Joe: 5 Things You Didn’t Know About Coffee. Encyclopedia Britannica. https://www.britannica.com/list/5-things-you-didnt-know-about-coffee
2. Myhrvold, N. (2021, November 16). coffee. Encyclopedia Britannica. https://www.britannica.com/topic/coffee
3. Caterina, D. R., Martinez, A. J., & Kohlmeier, M. (2019). Principles of Nutrigenetics and Nutrigenomics: Fundamentals of Individualized Nutrition (1st ed.). London, United Kingdom: Academic Press.[4] Guest, N., Corey, P., Vescovi, J., & El-Sohemy, A. (2018). Caffeine, CYP1A2 Genotype, and Endurance Performance in Athletes. Medicine & Science in Sports & Exercise, 50(8), 1570–1578. https://doi.org/10.1249/mss.0000000000001596