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Genes and Caffeine sensitivity

For some of us, even a single cup of coffee or tea can trigger palpitations, and make us feel jittery, but others enjoy cups upon cups of coffee and tea in a day without flinching. Ever wondered why the same caffeine produces different effects in different people? Read below for answer to this question and more.


Genetic link to caffeine sensitivity

The liver processes and clears the ingested caffeine using an enzyme called CYP1A2, which is produced by the CYP1A2 gene. In people who genetically produce more enzyme- called fast metabolizers, caffeine is quickly excreted from the body, hence they can tolerate more caffeine. In people who genetically produce less enzyme-called slow metabolizers, caffeine circulates in the body for a longer time before being excreted- these individuals may display symptoms of caffeine overload.

Another genetic link to caffeine sensitivity involves the type of adenosine receptors a person has in his/her brain. Those lacking the correct adenosine receptors in their brain are unresponsive to the awakening effects of caffeine because the caffeine molecule cannot properly bind to the receptors. As an example, imagine a color blind or less color sensitive person who is unable to see the various colors in objects. Similarly, there are individuals with a degree of “blindness” to the effect of coffee. We see this in various walks of life. Some people can tolerate lots of spices and others cannot. Some people need to ingest a lot of alcohol before they get drunk, others feel inebriated with little amounts. There are underlying genetic sensitivities for various things we consume daily.

Based on the caffeine sensitivity, people could be categorized into three groups.
You should be able to identify your level of caffeine sensitivity based on the three descriptions above. So, the daily recommended levels of caffeine for normal individuals is around 300-400 mg, which equates 3-4 cups of brewed coffee or 7-8 cups of black tea. People who are hypersensitive should self-monitor for symptoms associated with various levels of coffee intake and moderate accordingly. For individuals with less tolerance to caffeine, several other options such as Black tea, green tea, decaffeinated beverages are available.


Other Factors affecting caffeine sensitivity

In addition to the role played by genes, various other factors have been found to affect CYP1A2 activity and therefore to increase or decrease the amount of time it takes for caffeine to be cleared from the body.

Increased speed of caffeine metabolism Decreased speed of caffeine metabolism
Cruciferous vegetables (broccoli, cauliflower, cabbages, radishes) Apaceious vegetables (celery, carrot, parsley)
Coffee Alcohol
Grilled meat Grape fruit juice
Tobacco smoke Liver disease
Lean people Obese people
Younger people Older people


Myth about Caffeine

It is only present in teas and coffees


Several other common beverages like carbonated beverages, sports drinks chocolates, energy drinks and other food items contain caffeine.


Key takeaway

Be self-aware of your reaction to consumption of caffeine. If you experience no symptoms described above with normal amounts of caffeine intake, then you likely have normal tolerance for caffeine. If you do have symptoms, then you may be less tolerant.

You could also consider a genetic test that informs you about your sensitivities and metabolism of the various foods you consume on a daily basis.



Xcode is a pioneer in personal genomics, focussed on enabling personalized preventive healthcare. We are dedicated to empowering physicians, wellness professionals and customers with the most validated, accurate and actionable genomic information to positively impact and improve their client’s health and quality of life.

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