Coffee is good for you—unless it’s not! | Chris Kresser
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Coffee Is Good for You—Unless It’s Not!


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Numerous studies have linked drinking coffee with positive health effects like reduced risk of obesity, diabetes, and heart disease. However, recent research suggests that the effects of coffee on health aren’t the same for everyone, and may depend on genetics and other factors.

slow caffeine metabolism
Many feel that coffee is an important part to the start of their day.

I love coffee—and I’m not alone.

Americans drink 400 million cups a day (yes, you read that correctly) and we spend $30 billion on it every year.

The good news is that there’s a lot of research that links drinking coffee with health benefits, including lower risk of cancer, Parkinson’s disease, obesity, diabetes, metabolic syndrome, and heart disease. I covered that research in detail in a recent podcast.

Here’s the bad news: while coffee is undoubtedly beneficial for some people, it may be harmful for others.

I talked about some of the factors, including sleep, stress, and intolerance to proteins in coffee beans, that determine individual response to coffee in another podcast a while back.

But there’s another important factor to consider: genotype.

Coffee is the primary source of caffeine for Americans. Caffeine is metabolized by an enzyme in the liver that is encoded for by the CYP1A2 gene. Unfortunately, about 50 percent of the population has a variant in the CYP1A2 gene that leads to slow processing of caffeine.

For these “slow metabolizers,” drinking coffee:

  • Is associated with a higher risk of heart disease (1)
  • Is associated with a higher risk of hypertension (2)
  • Is associated with impaired fasting glucose (3)
  • May not have the protective effects against some cancers that it appears to for “fast metabolizers” (45)

That said, in some cases coffee appears to be beneficial even for slow metabolizers. For example, caffeine is neuroprotective and reduces the risk of Parkinson’s disease in both slow and fast metabolizers. (6) Other studies have even shown that fast—not slow—metabolizers of caffeine may be at higher risk of bone loss. (7)

Is coffee good for you? That depends.

Adding to the confusion, many of the large, observational studies I reviewed in my podcasts found that the overall effect of coffee intake in the populations studied was positive. If 50 percent of people are at higher risk of disease from drinking coffee because of their genotype, then why isn’t this showing up in these epidemiological studies?

What are we to make of these conflicting data?

The most obvious conclusion is that it’s impossible to make a general statement about the health impacts of coffee. The answer to the question, “Is coffee good for me?” is: “It depends.”

This shouldn’t come as a surprise. If you’ve been following my work for any length of time, or you’ve read my book, you’ve probably heard me say, “There’s no one-size-fits-all approach when it comes to diet.”

The most recent research on nutrition, including these studies on coffee and caffeine, confirm that this is true. While we share a lot in common as human beings, we also have important differences: genes, gene expression, metabolic activity, gut microbiome, lifestyle, activity level, and numerous other factors will differ from person to person, and all of these will impact how we respond to a particular food (or beverage, like coffee).

For example:

  • There is wide variation in post-meal blood sugar among people eating identical meals, and diets that are personalized on the basis of dietary habits, physical activity, and gut microbiota are more successful than “standardized” diets. (8)
  • Response to low-carb and low-fat diets in overweight people varies considerably and may depend on their insulin sensitivity and other factors that are not yet fully understood. (9)
  • Caffeine consumed in the afternoon or evening significantly disrupts sleep in some people, but not in others. (10)

These studies represent the future of nutrition research. In fact, I’m quite sure that in a relatively short period of time we’ll consider the current notion that there’s a single, optimal diet for everyone as an outdated and ignorant idea.

Another conclusion that we might infer from the conflicting data on coffee is that even within a particular genotype the effects are variable. In other words, some slow metabolizers might be adversely affected by caffeine where others aren’t, and the opposite might be true for fast metabolizers. This also makes sense because there are a huge number of factors above and beyond the CYP1A2 genotype that would influence how coffee and caffeine affect an individual, from their baseline diet to their stress levels and sleep to their gut microbiota. It’s also true that being a fast or slow metabolizer of caffeine isn’t binary (i.e., two possible speeds: fast or slow), but more of a spectrum (ranging from very slow to very fast).

Now that we’ve established that coffee and caffeine can be both beneficial and harmful, how do you know how it affects you? Here’s what I suggest:

  1. Listen to my podcast called Is Drinking Coffee Good for You? in which I discuss some of the non-genetic factors that determine individual response to coffee.
  2. If you haven’t already done this, titrate yourself off coffee (reduce your consumption slowly until you’re off it completely) and other sources of caffeine for at least 30 days. Then add it back in and see how you respond.
  3. Find out whether you’re a “slow” or “fast” metabolizer. You can get this kind of genetic data through companies like 23andme and SmartDNA. If you’ve done 23andme, log in, go to “My account,” select “Browse raw data,” and type “CYP1A2” into the “Jump to a gene” search box. Once on the search results page, find the rs762551 SNP. In the far right column, it will give your variant of that SNP. If you are AA, you’re a fast metabolizer. If you are AC or CC, you’re a slow metabolizer (with CC being slower than AC).

We live in exciting times. At some point in the future, we’ll be able to create much more precise nutritional recommendations based on our genotype and epigenetic factors, in addition to all of the other factors I’ve discussed in my book—such as health status, lifestyle, physical activity, and goals.

Right now, we’re only scratching the surface and still have a lot to learn. But we already know enough to stop asking questions like “Is coffee (or carbohydrate, fat, etc.) healthy” and start asking questions like “Is coffee (or carbohydrate, fat, etc.) healthy for me?”


Join the conversation

  1. I am very sensitive to coffee, and even one cup in the morning can keep me wired all day, and have trouble sleeping that night. I think this may be atleast partly to do with having fibromyalgia, which apparently makes my nervous system very sensitive already. My mum has recently stopped drinking caffeine, and she’s says it must have been slowly ‘poisoning’ her for years, as she has double the physical energy now and much better wellbeing. So maybe my sensitivity is genetic too. I actually am using coffee ATM though to alter my sleep pattern, as due to my chronic fatigue, I go to bed at 6pm, which causes problems with night eating and early waking. So I’m drinking a cup of coffee now in the mornings to try to stay awake later. Thank you for these excellent articles.

  2. Chris, have you heard of Your article could have been a advertisement for that program. I’d love to have you do an article or podcast about it. I don’t think it’s all 100% correct, but it’s definitely the future of diet and overall health.


  3. Coffee has almost no effect on me. I drink a couple of strong cups every morning, and sometimes another in the afternoon, and my husband and I drink espresso every night after dinner, never with any problem sleeping. Also, if I drink coffee in the afternoon I can immediately lay down and take a nap… No effect! I just like the taste, especially with heavy cream!!!! Must be a very fast metabolizer. I do notice that I always have to pee exactly three times within an hour of my coffee in the morning!

    • It does not mean that you are necessarily a fast metabolizer of caffeine. You may simply have developed a caffeine tolerance, i.e. your brain is not reacting to caffeine. However, silently, the caffeine may attack your heart and the damage may be slowly accumulating until it will show up later in life. This happened to me. I used to drink a lot of coffee like you without having a problem and without knowing that I am a slow metabolizer (CC genotype). At the very beginning of drinking coffee I felt some stronger heartbeat but did not pay attention too much. Continuing drinking coffee it disappeared but returned after my 50! One can not be sure without the genetic test results. If I knew before, I would certainly avoid drinking too much coffee if any…

    • Coffee is a diuretic and can also have a laxative effect. It’s always recommended to drink water after having coffee. Most cafes in France and Italy serve espresso with a glass of water 🙂 – how considerate!

  4. I recently switched to tea – green, oolong or black. I find tea to be very different from coffee not only in terms of caffeine content but also in terms of the quality of the stimulating effect. Apparently there are some components in tea like theobromine and L-theanine that work synergistically with caffeine and create a more balanced buzz without the jitters. A kind of alert relaxation.
    I’m in a process of healing my adrenals and tea works great for me right now.
    I wrote more about it here:

  5. I am definitely a slow processor of coffee. I had never been a coffee drinker until a few yeas ago. When I consistently drink coffee every day this is what I notice: sleep disturbances, blood sugar and digestive upset, muscle / bone / joint aches (truly I wake up every day feeling like every cell in my body aches), and poor exercise recovery time (a 1 1/2 hour yoga class would leave my body seriously aching for 4-5 days and I have been doing yoga for 16 years). I stop coffee and it all ends.

    Bummer I say as a hot cup of coffee with lots of full fat (pasture raised) goat’s milk is a delightfully creamy way to start the day.

    I have tried all of the coffee substitutes, and many are yummy, but they do not taste like coffee.

  6. Chris, you talk about ‘slow metabolizer’ of coffee; if one is AC or CC does this make them a slow matabolizer in general? E.g., metabolize food slowly, difficult to lose weight, slow to move, etc? Thanks!

    • I’m CC, but have no problem staying lean. So I don’t think it’s related to metabolism in a weight loss sort of way.

    • The metabolism of caffeine happens in the liver and it’s the detoxifcation of that caffeine that we’re talking about when we say “caffeine metabolism”. So if the detoxification process is slow, we say someone has slow caffeine metabolism. Having fast or slow caffeine metabolism does not mean someone will have fast or slow metabolism in general.

  7. I am an ‘ultra fast metabolizer’ according to my genetic data. Accordingly, I can drink a cup and fall asleep instantly. Currently I am only drinking tea, as the acidity of coffee bothers me. 2 cups green tea, 2 cups black during the day. I have been off of caffeine for long periods due to HPA axis issues, but I generally feel better on it.

  8. 23 and Me results show that I am a slow metabolizer of coffee. It has been so hard for me to give up my morning cup because I enjoy it so much. I sometimes get sick due to the acid on my stomach. It is part of my morning time to myself. I tried to replace it with green tea which is beneficial for my O blood type but I am allergic to green tea. Also allergic to red wine! Try to limit myself to one cup. Eat mostly a Paleo diet. My results also showed that a low fat diet would make me fat. I followed a low fat diet for almost 20 years. I was a skinny fat. Now with Paleo diet I have noticeably less fat. My husband is blood type A and a fast metabolizer. A low fat diet with vegetable protein benefits him. It was our 23 and me results that led us to realize there is an individual diet for everyone. I believe the day will come where each person can get an individual diet for their optimal health. It will be their decision to follow it!

  9. I’m sure I’m in the “fast” category – I am always a good sleeper and can drink a cup after dinner without if bothering me…pretty much got off of coffee with my “reset” month – am happy to have coffee back in my life?

  10. I stopped drinking coffee when i was studying for my final exams in high school (1984). While studying, i switched to eating more fruit and felt better. I didn’t really go back to drinking much of it after that. However, years later (in my 30s), i developed insomnia – lots of stress – and one day i had a cup of coffee. My heart starting beating so wildly i thought i was going to have a heart attack!. I remember having that coffee some time in the early hours of the afternoon, but i still couldn’t sleep at all that night. The only time that coffee hasn’t effected me since then is when i drank a couple of cups of decaffeinated organic coffee made locally in Melbourne, Australia. In the past i tried decaf, but had pretty similar effects to regular coffee. This organic brand tasted so mild and delicious i simply couldn’t stop at one, and I didn’t care about the lack of sleep it was going to bring me. To my surprise, i had no effects whatsoever. I didn’t push my luck – i stopped there, but will try it again out of curiosity – one day in the near future.

  11. I have become somewhat desensitized to caffeine. Even tea after 2:00PM used to keep me awake. Now its just if I have sugar with the coffee. Since I’ve started to spike my coffee with
    coconut oil and some protein powder, I notice that the jitters are gone.

  12. I was one of those people who had no problem with caffeine: coffee in the morning, lots of black tea during the day, and chocolate at night. About a year ago, I did Chris’s 30 day reset and then went on a moderately low carb paleo regimen, on which I feel great and have lost weight. But a few months in, I developed a severe reaction to caffeine. Once cup of coffee and half and hour later my heart pounds and misses beats. It’s scary! I was wondering if going off a low-fat, high-carb diet and onto a paleo one, can affect caffeine tolerance? Has anyone else had this experience?

  13. I’ve never drunk coffee in my life – can’t stand the taste or the smell. Especially, I can’t tolerate standing next to someone with coffee breath. However, I used to drink iced tea (I’m from the South) all day. I can’t/don’t do that any more because even tea now makes me jittery to the point that I feel as though I’m having panic attacks. Chocolate makes my stomach hurt and I love it – I just allow myself one little piece once in a while knowing that I will just spit it out – not worth the discomfort but I still get the taste. Strange, huh?

  14. That’s odd. It turns out I’m AA and yet I have been off coffee tea and anything else caffeinated for most of my life because it affected me so much. This makes no sense yo me at all.

  15. I’m following an autoimmune protocol but LOVE coffee and think it is my only true vice, in that I find it very difficult to completely eliminate from my diet. Eliminating grains, legumes, dairy, and greatly reducing sugar has been much easier than trying to manage my coffee craving. I allow myself one black coffee a day, and never past 2pm as I know even that will have me awake til midnight. I used to find I ‘burned out’ on coffee and would become emotional and jittery. I’ve found supplementing with a good quality magnesium has helped enormously with this.

  16. I have been diagnosed ADHD (suspect it’s actually ASD though), and appear to metabolize caffeine and even medicines quickly! I used to go grab a 20 oz coffee at 9 pm (I worked days, and started work at 8 am), and would have people ask if I planned on sleeping. I was, for a long time, curious why they would say that! I would head home and hit the hay at 11 pm and fall asleep before my head hit the pillow. Great sleep all night too. I’m trying to not use it now because I think I may have adrenal problems. I miss it though. I noticed I do have a problem with sleeping with alcohol though. Wine make me wake up a lot when it leaves my system.

  17. I gave up caffeine about 4 months ago and after 5 days of awful headaches started to feel so much calmer, my menopausal flashes and night sweats have disappeared, except for slight flashes if i eat too much chocolate. Never really tolerated it well but got less tolerant after my hypothyroidism diagnosis at age 29 and even less tolerant when diagnosed with type 1 diabetes at age 36. I will never consume caffeine on a regular basis again as I am feeling so chilled but energetic at the same time and no more frightening palpitations

  18. I love coffee, and I love caffeine. I must be a fast metabolizer because it doesn’t disrupt my sleep even if I drink it in the evening. However, I did give up coffee (VERY gradually) this year because of a positive IgG ELISA test. I realize this test is controversial, but I figured it would not hurt to give it up for 2 reasons: (1) possible weak adrenals, and (2) I become so highly dependent on caffeine that I will get a severe headache if I don’t get my fix.

  19. Do you think it is possible for coffee compounds and/or caffeine to cause elevated CPK (muscle breakdown) in certain individuals?

    I read this book last year “Welcome to the Dance: Caffeine Allergy – A Masked Cerebral Allergy and Progressive Toxic Dementia” in which author Ruth Whalen discusses her experience with unexplained health issues (Physical and Mental) including elevated CPK and ultimately links it back to coffee/Caffeine consumption.

    I too have had labs with slightly elevated CPK levels for unknown cause that seem to return closer to normal when decreasing caffeine. I can’t find too much other information to support this online.

    I am a slow metabolizer and have found discussions on caffeine’s negative effects on sleep and anxiety but not much related to the idea of caffeine/coffee compounds causing a cumulative toxic effect overtime that could induce CPK muscle breakdown and other psychosis systems in susceptible individuals.

    Thanks for another great article Chris!

    • i am addicted to caffeine and it raises my blood pressure and swells my legs and eyes as well as making me more hungry. However I dont want to get out of bed without it so I struggle. Once off coffee and its a 5 day of depressions to do it I feel better but so calm I could put myself to sleep any hour of the day in 3 minutes. Not a useful way to live. Week adrenals and metabolic syndrome is encouraging me to give it up . I am a slow metabolizer and methylator as my liver considers it toxic . So why did I have it today ?
      Perhaps not tomorrow

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