[e9]

We all have gene in our liver for making enzyme that breaks down caffeine. Due to small genetic differences, some of us have enzyme that breaks down caffeine quickly and others that breaks it down slowly. If you win genetic lottery and produce enzyme that breaks down caffeine fast then you flush out caffeine and end up reaping benefits of antioxidants found in coffee beans. If you have enzyme that breaks down caffeine slowly, caffeine hangs around longer causing health problems. That's all there is.

[ryanmerket]

This. I’m a slow caffeine metabolizer and had to give up caffeine.

[epalmer]

How do you determine you are a slow metabolizer of caffeine?

[SOLAR_FIELDS]

Anecdotal: If you aren't able to fall asleep as easily 6 hours after a cup of coffee vs 10 hours you might be a slow metabolizer.

Strangely enough, if you find yourself in this situation of having drank coffee too late in the day nicotine has actually been proven to speed up the metabolization of caffeine: https://www.ncbi.nlm.nih.gov/pubmed/3365914

[epalmer]

I can usually drink coffee within an hour or two of bed. I don't normally do that but I can. On the weekends I drink 2 to 3 cups in the early morning around 5AM. Then around 2 pm I usually drink 1 to 2 more cups.

At 70 something my dad watched a TV show on ADD and said to my stepmom, I think I have ADD. He want to the doctor and told him the same. The doctor said, we don't test for ADD, instead we have assessment questions. He asked my dad, first question "How many cups of coffee do you normally drink?" Dad said 15 to 18 a day. Doctor said we are done. You have ADD.

He was on ritalin the rest of his life. I don't agree with having him on ritalin but that was not my choice. He died of old age at 83. Until a year before his death he had been very healthy. NEver got colds, the flu or anything like that. Had a little spring hay fever. That was all.

[Noumenon72]

The way you present your doctor, if I told him I was taking 8 sleeping pills a day, he'd diagnose me with narcolepsy instead of telling me to cut back on the drugs.

[epalmer]

My dad's doctor and not mine. Keep in mind this was antidotale from my dad. I'm sure the conversation was longer but that is how he (my dad) represented it.

[eighthnate]

Wow, I didn't know that. I gave up smoking a while ago and now think smoking is a terrible and costly habit/addiction, but I still miss smoking a cigarette while enjoying a nice cup of coffee.

I wonder if the metabolization benefits of nicotine actually made coffee more enjoyable on a physiological level.

[_ywdj]

An educated guess: you get stronger negative reactions to caffeine: anxiety/panic, aggression, insomnia, heart racing and/or palpitations, sweats, tremors/muscle spasms, dehydration.

That said, I don't think it's as genetically hard-coded as the the root comment suggested.

I've been through episodes (coinciding with when I was having debilitating symptoms of chronic fatigue and depression), when I experienced these symptoms (sometimes very severely) when consuming caffeine. As I've become more physically energized and mentally well, my tolerance for caffeine has vastly improved.

[mrfusion]

It’s weird I have the fast version of the gene yet I can’t sleep that night if I even have a small cup after noon.

[nastygibbon]

Do you have a source for this?

[e9]

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4242593/ In section "Genetics and long-term effects of caffeine" it goes a bit into details but here is relevant excerpt: "The finding of lower COMT activity with higher risk of myocardial infarction points to involvement of circulating catecholamines in caffeine’s effect on cardiovascular system, with the implication that slow-metabolizing individuals could be at increased risk due to decreased ability to handle the stress associated with caffeine-induced catecholamine response."

if you want to know more about caffeine in general this place sites all the studies: https://examine.com/supplements/caffeine/

[vesak]

https://en.wikipedia.org/wiki/CYP1A2

[jooke]

Where on this page does it say that having this mutation makes coffee less harmful?