Why Some People Can’t Handle Coffee

Can you drink seven cups of coffee without feeling like you’re going to have a heart attack? Or have you been called a lesser human because you hate the way coffee makes you feel? You may think you have control over your relationship with coffee, but it might just be genetics!

Most people drink about three cups every day, I’d say. Some people could probably drink 20 cups without dying. Coffee makes them feel sane and like a human. The days that they don’t drink coffee, they feel like those days are just going to be long and miserable, and they don’t really start until they’ve had coffee. How many cups of coffee do you drink a day? Some drink zero cups of coffee a day. Coffee makes them feel like their insides are on fire, and that their blood is trying to escape from their body through every pore.

I personally can’t drink a whole cup of cold brew without feeling like I’m going to die. I get this jittery feeling like my heart’s going to pop out of my chest. It may be different for you. I don’t know your life, and I’m not going to pretend that I do, but there’s a reason why everybody responds to caffeine in a different way. The way your body metabolizes caffeine is partly based on your genetics. A recent study by Dr. Marilyn Cornelis at Northwestern University revealed that a variant in a specific gene in your body is responsible for breaking down caffeine at different rates.

Why is it that some people can kind of drink a bunch of coffee and not feel anything, or just feel a little bit of stuff, while others like me can’t even have one glass of cold brew, and we’ll just freak out and have a panic attack?

Metabolizing Caffeine

There are a number of factors for why people might consume more coffee than someone else. But much of the research now is showing that it has a lot to do with the way you can metabolize caffeine. What does coffee metabolism mean? When we think about coffee, people naturally equate coffee with caffeine. To make it simpler, we talk about caffeine metabolism. It further varies our ability to break down caffeine into its metabolites that have less activity, so they don’t provide those stimulant effects. If caffeine remains unmetabolized in your body, you continually feel the stimulative effects of caffeine.

So does this mean that, depending on someone’s genetic makeup, more caffeine can stay in the body, compared to other people? Yes, genetics is one component. There are other factors, too. For example, smoking actually increases your ability to metabolize caffeine. So, smokers tend to consume more caffeine in order to get the same kick that other people, or non-smokers. Wow! Why is that? Some of the key chemicals in tobacco smoke induce the enzymes that metabolize caffeine. Their enzymes are acting faster.

Positive and Negative Effects

Just more generally, what are the beneficial effects that people feel, for people who enjoy coffee? Generally, we think about the stimulant effects. People will say, “I’m working all day.” They might feel that they need to get a bit of a kick in order to keep them awake, remain stimulated, and act efficiently. Others just kind of feel good. Everyone responds differently.

What are some of the negative effects that are noticed for people who don’t enjoy coffee, or who can’t drink a lot of coffee? The typical ones are the jitters and anxiety, and those are our obvious responses to caffeine. That kind of tells you to just cut back on caffeine. Does that explain why some people just love that kind of stimulant activity, while some people just really don’t like it or don’t respond well to it?

Actually, there are a couple of studies in this area. In one, where they looked at coffee consumption behavior. In a different study, they looked at the caffeine metabolite levels of the blood. What they found is that people with the genetic variance that results in increased coffee consumption also had lower levels of caffeine in their blood. This shows you again that they’re metabolizing caffeine so quickly that they need to consume more in order to get that caffeine fix.

What are the genes that are identified? The key one is cytochrome P450 1A2. CYP1A2 is the short version of it, and they refer to it as the xenobiotic metabolizing enzyme. It’s responsible for 95% of caffeine metabolism. Everyone has this gene, correct? Everyone has a gene, but there are different variants within the gene. That’s where we find these individual differences between people: in the CYP1A2 activity.

Can Your Coffee Habits Change?

So, if it’s true that genetics, for some parts, play a role in coffee consumption, will I always be a person that can’t drink coffee? Or can I kind of condition myself, or how does that work? That’s a great question to ask. That brings up what we call a “tolerance.” I guess you would have to at least get past your first cup of coffee and, if it’s the jitters that are bothering you, I guess you can try to kind of train yourself or condition yourself. That would probably take a while. In most cases, because you just don’t like it, you just won’t even try. But then, there are some people who don’t like coffee—not at all—because of the genetics or their response to caffeine. They don’t like the taste. There is also genetics for taste, as well.

For example, for me, I really like the effects of caffeine. I can get caffeine from other sources, such as colas and other things. If it is genetics, can I pass it down? Is it heritable? Yes, it is. Obviously, you would get part of the genes from your mother and your father. And if they’re both heavy coffee drinkers or are rapid caffeine metabolizers, then it’s highly likely that you will be a rapid metabolizer as well. Wow, so just blame your parents.

Like most of our other bodily characteristics, genetics play a huge role in influencing our caffeine intake. Typical. But hey, at least it’s not your fault you can’t pound coffee like you’re a Gilmore girl. How many cups have you had this morning? There are people that can guzzle an entire can of Maxwell, just like there are people who can survive a college kegger without a vicious hangover. It’s just their biology. Also, people hate coffee for a plethora of reasons like taste and smell, and that’s biology, too. The body just won’t give us a dang break. It’s also very interesting to find that coffee metabolism is heritable. So, just like every other issue in your life, blame your parents. It works every time…

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