Have you wondered why some people can drink coffee during the evening, and still fall asleep? Others, if they have a few sips at 3 p.m., they stay awake all night. The answer is in our genes.
Depending on which genes you inherit from your parents, you will metabolize caffeine either faster or slower. Faster metabolizers will break down the caffeine in their bloodstream quickly, so that even if they drink it at night, their system works so quickly that the caffeine is already broken down by into more inert components by the time they are in bed.
Studies done at Harvard, in Canada, and most recently in Italy have found that there are actually several different genes involved. These genes control various liver enzymes that break down the caffeine chemical.
One gene involved is called “CYP1A1”, and you inherit one of these genes from your mother and one from your father. The gene comes in two varieties—the “fast” one and the “slow” one. If both your parents have the “fast” variant, you will have two copies of that fast gene in your system. You will metabolize coffee about 4 times faster than a person who has one or two copies of the slow gene variant.
About 40% of people have two copies of the fast CYP1A1 gene and they are considered “fast metabolizers”. About 45% have one copy of the fast gene and one copy of the slow gene, and 15% have two copies of the slow gene. These last people will be the ones who cannot tolerate any coffee in the mid-afternoon or they just won’t fall asleep.
Interestingly, the researchers have found that people naturally learn to drink coffee depending on how they metabolize caffeine.
How do you respond to coffee?
Slow metabolizers tend to have a gradual awakening effect when they drink coffee, which can last many hours till it slowly goes away. Fast metabolizers notice something different. These people will notice an almost immediate increase in alertness when the costume it, followed by a relatively quick drop in energy. This person will tend to drink coffee several times a day, and will be able to drink at night since the caffeine is out of their system quickly.
Researchers are discovering that people should probably follow what their body is telling them about their caffeine metabolism, since it will affect the way coffee impacts their health. For example, people who are slow metabolizers (who naturally would not drink much coffee), but if they force themselves to drink a lot, they will have an increased risk of heart attacks as well as high blood pressure. People who are fast metabolizers and drink a lot of it will have the opposite effect. For them, coffee protects their heart and blood pressure.
Health effects of coffee
While the health effects of coffee are still controversial, most studies indicate that, for most people, drinking coffee will help lower their risk of heart disease, diabetes, liver disease, Parkinson’s disease, and even dementia. People who are slow metabolizers though may not enjoy the healthy benefits of caffeine. More research needs to be done, but the research indicates that you should listen to your body regarding how you handle coffee. If you are a slow metabolizer, it’s probably ok to occasionally drink more coffee than normal if you need to stay awake that day, but don’t make that your daily habit. Fast metabolizers can probably drink more freely without worry.
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