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Sensitive to caffeine? Your genetics are to blame

What is caffeine sensitivity? 

Caffeine helps us get out of bed in the morning, helps us tolerate our coworkers more, and may even be good for heart health. For some, though, caffeine consumption results in jitters and anxiety. But why does caffeine effect people so differently?

How often you drink coffee and how you take it definitely play a role — and your genetic makeup is a huge determinant. Yes, genetics help tell the story of how your body responds to caffeine. Finally, a biology lesson I care about (sorry to my high school bio teacher). 

The science behind caffeine sensitivity

People who metabolize caffeine quickly are less sensitive to caffeine than those who take longer. Fast metabolizers (called hyposensitivity) don't feel the jitters or anxiety that slow metabolizers (hypersensitivity) feel. 

These two extremes are determined by variants of the CYP1A2 gene, which codes for an enzyme that breaks down caffeine. About 45% of people are considered fast metabolizers because they inherited two copies of the CYP1A2 gene variant — one from each parent. Thanks, mom and dad. 

The AHR gene also plays a role in caffeine sensitivity because it regulates turning on and off the CYP1A2 gene. Another link is the type of adenosine receptors a person has in their brain — those lacking the correct adenosine receptors are unresponsive to the awakening effects of caffeine because caffeine molecules can't bind to the receptors.

There's also tons of research being conducted about genetic factors and caffeine sensitivity. The Harvard School of Public Health found six new genetic variants that could affect how people metabolize and form addictions to caffeine. 

It's important to note that caffeine sensitivity and caffeine tolerance are not the same thing. Caffeine sensitivity has to do with your genetic makeup, whereas caffeine tolerance is when your body is less likely to respond to caffeine because of how often you drink it.

The three levels of caffeine sensitivity 

There are three levels of caffeine sensitivity based on current data. They are: 

  • Hypersensitive to caffeine
  • Normal sensitivity to caffeine
  • Hyposensitivity to caffeine 

Hypersensitive people react to even the smallest amounts of caffeine, and often experience insomnia, jitters, and an increased heartbeat. People with normal sensitivity can usually have between 200 mg and 400 mg of caffeine — this is where the majority of people fall.

Hyposensitive people, on the other hand, can take in more than 500 mg of caffeine without much effect at all — these people can also have caffeine before bed without it affecting their sleep. Talk about best case scenario.

Related: This is your brain on caffeine

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