Gene in Focus: Part 4 - CYP1A2 (Caffeine)

The next gene we'll be looking at is CYP1A2. The enzyme produced by this gene is responsible for about 95% of all caffeine metabolisation in your body. This is why we include CYP1A2 in our caffeine report. It also plays a role in phase-1 detoxification, particularly in how well your body deals with HCAs and PAHs found in charred meats.

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As with all our genes, there are two different CYP1A2 alleles, in this case A and C. The A allele is associated with a higher activity of the CYP1A2 enzyme, and the C allele is associated with lower activity of the enzyme. 

CYP1A2 and your genetic caffeine response

Research on the effects of caffeine on cardiovascular health found that the effect of caffeine differs between genotypes. With regard to caffeine response, AA genotypes tend to metabolise caffeine quicker than AC and CC genotypes. As a result, AA genotypes are called “fast metabolisers” and the AC and CC genotypes are classed as “slow metabolisers”.

A 2006 study found that slow metabolisers who had more than about three cups of coffee per day, increased their risk of suffering from a myocardial infarction (heart attack). Fast metabolisers, however, didn’t see an increase in heart attack risk. The same is true for hypertension. A 2009 study found that higher amounts of caffeine (around 300mg per day) was associated with an increased risk of hypertension – but only in slow caffeine metabolisers. Based on these studies, and others like them, DNAFit recommends that slow metabolisers should limit their intake of caffeine to around 200mg per day. Fast metabolisers can consume more caffeine should they wish, up to approximately 300mg per day.


What does 200mg of caffeine per day look like? 

200mg of caffeine is equivalent to:

  • approximately two cups of brewed coffee
  • approximately four cups of tea
  • approximately two energy drinks


CYP1A2 and phase-1 detoxification ability

We also look at CYP1A2 from the perspective of phase-1 detoxification ability, which looks at how well your liver can handle two compounds found in cooked meats. These compounds are HCAs and PAHs which form when meat is cooked at a high temperature, and has become blackened, crispy, or chargrilled. When we eat this meat, our body starts to break down these HCAs and PAHs creating a toxic by-product.

If you breakdown these HCAs and PAHs quickly, you get a rapid increase in this toxic by-product which overwhelms your body. However, if you break them down slowly, you get a much gentler increase in the toxic by-product - lowering your risk of toxin build up.

CYP1A2 is one of the genes involved in this pathway, and A allele carriers are classed as fast metabolisers, with CC genotypes classed as slow metabolisers.

In the case of fast metabolisers, we recommend that they limit their consumption of grilled or smoked meats, and focus on protecting the meat during the cooking processes. This requires using a lower cooking temperature - so, cooking with a liquid (curries, stews, stir fries, marinades) should help with this.

As you can see, your version of the CYP1A2 gene can have an impact on how well you tolerate caffeine, and how well you process HCAs and PAHs. Both of these things can have a profound impact on your future health. By understanding your body on a genetic like this, you can make important dietary changes which can maximise your health both in the short and long term.

Take the DNAFit test to discover your CYP1A2 genotype, to see how much caffeine you can tolerate on a daily basis - without damaging your health.

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