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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. istock.com/kyoshino

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.

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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?”

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Join the conversation

  1. I live on coffee some days having 6 cups I have not done any genotyping but was wondering am I a fast coffee metabolizer since the caffeine does not affect me or keep me awake at nights. I can drink a cup of coffee and go to bed and have no affect on my sleep.

  2. Hello Chris,

    Great article! I am writing on behalf of FitnessGenes and we test individuals for the caffeine metabolizing gene you have mentioned in your article (rs762551 SNP, the same as 23andMe). As you have mentioned, individuals can be separated into those who carry ‘fast’ and ‘slow’ caffeine metabolizing genes.

    At FitnessGenes, we also agree with your statement that fast and slow caffeine metabolism speeds are more likely to be on a spectrum than just two speeds. This is because we have found, when doing our research, that caffeine metabolism in fast metabolizers is inducible. That is, someone with the AA genotype may only start to metabolize significantly faster than someone with AC or CC if;

    They live in a polluted area (air pollution)
    They drink more than 3 cups of coffee a day
    They smoke
    They eat lots of leafy, green vegetables.

    Interestingly, the studies we reviewed showed this but also showed that eating lots of leafy green vegetables increased the speed of caffeine metabolism for both AC and CC individuals too! This is probably why there are some individuals who are AA who feel they are slow and maybe some who are AC and CC who feel they are fast or unaffected by caffeine (some allude to this in your comments section).
    We give our customers this information with quoted studies. The diseases you have mentioned (heart disease, hypertension, impaired fasting glucose, cancer) can be caused by a wide combination of both genetic and lifestyle factors which makes some studies on caffeine metabolism and disease risk hard to disentangle. Also, FitnessGenes is a fitness DNA testing company, we do not advise on disease risks, and we focus primarily on fitness advice designed to get people into the best shape of their lives!!

    Feel free to get in touch to find out more!

    Dr Dan Reardon, CEO of FitnessGenes

    • Any specifics on the greens or reasons for it? Any links to the studies that back up those conclusions? Love to read about it in detail.

  3. Hi Chris,

    Thanks for all the wonderful things you do!

    Started the diet 5 months ago and have lost 43 lbs. and have never felt better.

    Regarding the coffee issue, I used to practically pass out 10 minutes after I had a cup. I cut out coffee completely for the diet. Now I’ve reintroduced it and have no ill effects. I realized when I Used to have coffee I’d always have it with a teaspoon of raw sugar.

    I can drink coffee now without feeling jazzed up or passing out, and I think it’s because the sugar gave me all those ill effects, not the coffee necessarily. So when someone is trying to determine what effect coffee has on them, maybe they should have it black, without cream or sugar. It may not be the coffee, but what you put in it, that’s the problem.


    Very Best,


  4. Hey Chris,

    I’ve been a coffee drinker my whole life. My family is Portuguese and we sure love our coffee! Over the last two years, however, I noticed that I would get chest pain on the left side all day. Sudden little jabs that would take my breath away. Anyway, a friend of mine was telling me that his friend drank too many coffees and landed up in hospital, thinking he’d had a heart attack, so I decided to switch to organic Swiss water decaf (because I love the taste so much). The chest pain went away after I made this change. I occasionally get the decaf mixed up with my husband’s coffee and if I do this more than once in a row, the pain returns. It’s very strange, considering I was quite fine with coffee for so many years beforehand.

  5. It’s not only how you metabolize coffee, it can be the long term effects you experience. I’ve never been a big coffee drinker but I had been using it for several months when I noticed I didn’t have the energy I use to have. I stopped drinking coffee and about a week later I was back to normal. I don’t believe the hype about how good it might be. I think there is a lot a marketing going on with it.

    • I so agree on the marketing hype around so many “food substances” that are supposed to be good for us. Hype sells when the food is raised to a “superfood” level.

      I never have been a coffee drinker (as I do not tolerate caffeine well) and then at 45 or so started drinking occasionally with my partner. Little by little it became a daily habit. I found myself suffering from low level muscle, bone, joint, (all over body aches), low energy, and a host of other ill symptoms that made me wonder about Lyme disease, rheumatoid arthritis, etc.

      Stopped coffee and all is fine again.

      Slow metabolizers of caffeine are creating a back up of toxins in the body when they use caffeine regularly. The liver can only detox so much before it gets over loaded. Toxins in the system make for ill health symptoms.

      Some people thrive on a coffee, others do best avoiding it.

  6. Serious question: I drank five cups of coffee yesterday afternoon, last one about 5pm. Worked till 9pm, then watched some tube. Went to bed at 11pm and slept like a baby. Can I reasonably infer that I’m not a slow metabolizer? I kinda hate the thought of weaning myself off for a month, if I’m not having any issues.

  7. I have avoided coffee for most of my life, but this summer on holiday in France, I started drinking a couple of cups every day (black, organic, strong). At the end of the holiday, I noticed that I had broken out in tiny little spots and ‘potential’ spots (ie, bumps) all over my chin. This is at the age of 43 when I’ve always had lovely clear skin.

    When we came back, my husband and I did the 14Four, so no coffee there, but I reintroduced it after the two weeks. Spots got worse.

    I searched the internet to find out whether coffee might be the culprit and came across this article, which seemed to indicate that it might well be.


    Since then I’ve cut back to one cup on a Sunday and the spots do seem to be slowly fading away.

    The whole episode slightly freaked me out as I have never had any issues with my skin at all, and it really knocked my confidence to start breaking out in spots at my age!

    The only other possible culprit might have been sudden high levels of animal fat in my food. In France, we ate lots of pate etc, and then we came back and did the 14Four with lots of traditional cooking fats.

    We’ve since moved to more coconut oil and less goose fat …

    I’d love to know if anyone else has found a connection between coffee and skin problems.

    • This was a long time ago but I thought I would share. I too have great skin. When I was in High school, I started getting pimples and my older co-worker told me to drink nothing but water for 2 weeks (I was drinking Pepsi). Pimples were gone and I was hooked on water. About 4 months ago I started drinking 1 cup of coffee in mornings, I noticed my skin does not look as good. I’m finishing up my last cup of ground coffee and plan on getting to bed earlier and drink homemade bone broth instead. Collagen in broth will probably be better for my skin than caffeine. Good luck!

  8. Hello Chris, thanks for the article. My mother had Parkinson, so wanted to make sure, as written in the article, that I will benefit from the caffeine, not from decaf. also, what is the minimum effective amount? I am probably a slow metabolizer, as caffeine keeps me awake for many hours. I was off coffee for about 6 months, not sure I can determine the effects on me. Thank you!

  9. I love coffee, not only the taste, but the relaxing feeling I get and the way it does away with the slight nausea I get when I wake up in the morning. However, here is the bad part: after a couple of hours, I get horrible heartburn and even acid reflux. It isn’t only coffee that gives me heartburn — so does meat and the very worst is red wine, followed by white wine, which l\hit my stomach like battery acid! This started about 5 years ago, and with every passing year something else is added to the list. Poultry, for example. Fish, so far, is fine. Acid vegetables like tomatoes and sour fruits cause instant pain. What, if anything, does coffee have in common with these things?

    • Hi Esther,

      Coffee is acidic as well, so that might be what’s common among these foods. Red wine is also quite acidic, while white wine is somewhat less. Do you also drink black tea? If you do and the effects are similar, that’s probably the reason. Maybe you could try to drink your coffee with some fats, cream if you tolerate it, or with coconut milk, coconut oil, or ghee.

    • You could have histamine intolerance, the foods you listed are all in the high histamine lists. Something to consider.

  10. I love coffee! But I do not love caffeine- it makes me “bouncing off the wall” jittery! I am looking forward to my next cup of rich, dark DECAF coffee… unfortunately it will be a long while before I can have it, as I am struggling with Candida and adrenal fatigue. Still love the smell when I brew it for my family.

  11. My love affair with coffee has taken a dive over the past 12 months. I backed right off from 1-2/day to 1-2/week in response to fatigue problems and found that it negatively affects my mood. I get “blood boiling” angry, flipping out at the most trivial things. Its like my body can’t handle the stress that the coffee seems to put me under. It only seems to have become a problem since having fatigue issues. I’m not sure if its the coffee, caffeine or both.

    • Caffeine will end in anxiety if I have too large an amount. Just one medium will push me over. I experimented after being successfully treated for adrenal fatigue. If you understand the mechanism of cortisol and caffeine:

      you can surmise that a large cortisol stimulant response would cause anxiety (anger, fear) and further tiredness.

  12. The bottom line for me is how I feel or intuitively expect to feel from any food or beverage. If it supports me I consume it, if not I don’t. I prefer not to dwell on the science and theories, only the results.

    Science is great when it is accurate 100% of the time. Unfortunately this is rarely the case so it can only be used as a guide.


    • That is good advice. That’s how people found out what to eat in the first place. The way we are made to operate. We should be in the woods too and we’ve lost so much common sense.

  13. Is the tannic acid in coffee bad for you? I have heard from several sources that it is bad for your stomach.

  14. I hope people are hearing you and perhaps also thinking that their animals don’t have one-size-fits all nutritional needs. Our animal friends need us to create the best and most personalized nutrition for them. We have fed our dogs, cats and horses custom, fresh, organic, homemade diets for years and they live a long time with very few health issues. Thanks Chris for your great work!

    • Most people I know take much better care of their pets health than of their own! I guess it’s a start.

    • What do you feed your cats? I want to cook for mine but am unsure how to do it. I tried once and the meat was too dry I think and he would only eat some of the juice.

  15. Great article! I think I’m one of the sensitive ones as well. If you are still wanting to get the benefits of coffee, check out the supplement EHT on my website!

  16. Always great to read your stuff, first class info, that is so profound ,yet simple to understand ,thank u so much for being such a great educator with real heart integrity,,,keep in on

  17. i’ve never liked coffee much, then 5/6 years ago i gave up all tea and coffee and only drank herb tea due to liver issues that were bettered, i think , mostly by cutting out sugar.
    a few months ago i had some coffee to stave of an impending migraine.
    i did this a few more times and since have become someone who enjoys coffee every day.
    i used to get a huge buzz, not so much anymore.
    it#s a really weird development but as i believe in going with my body’s cravings/intuition i am quite comfortable.
    it seems to help with my tendency to headaches/migraines and somewhat with my fibro fatigue.

  18. It is an interesting subject, coffee! This has been my experience. Whenever I drank regular caffeinated coffee, and then tried stopping, I would always get a “detox” effect of headaches and a general sick feeling for at least a day. So I decided to go decaf and not worry about “running out” of caffeinated coffee. This is the interesting part for me, when I went organic, and began drinking “organic” regular french roast coffee (strong), when I ran out of it, I DIDN’T have a “detox” reaction or sick day. In fact, nothing happened. I was so taken by this, I ran out a few times more, just to see, and nope, no “sick day” of any kind. So, I also have to ask, is the food in question grown organically or not now. Then, go from there. Of course, caffeine is caffeine, so, not sure what different effect it would have. I don’t “jump off the walls” after regular coffee. I could actually have it at night and sleep. But, then it’s “organic” so, really, I can’t say. Anyway, something else to add to the problem I guess 🙂

    • Coffee can be highly sprayed with pesticides, and it can get mold if not kept properly. I think you are right. Organic is the only way to go. Weirdly I find espresso at a good coffee shop makes me feel well as opposed to drip coffee anywhere else. Of course that’s not organic, but I’ve never seen organic sold at a cafe, just the beans you can make at home.

  19. This was fascinating! I’d love to get some of that testing done and find out whether I’m a fast or slow metabolizer.

    I’m particularly interested in the effect of coffee on migraines–any good info on that? I think too much coffee may be a trigger for me overall, but when I already have a migraine an extra cup seems to make it go away faster.

    Over the past four months I’ve reduced my coffee from 3 large mugs per day to 1 actual 8-ounce cup per day. I’m sleeping better and I lost some weight without really trying, which usually happens when I reduce or give up coffee. In the past when I’ve given it up entirely I’ve switched to green tea, but now I’m contemplating giving up all caffeine for 30 days and seeing how it goes…

  20. On top of the above issues mentioned, another spanner in the works here is for those of us who have been severely injured by fluoroquinolone antibiotics, & now suffer from what is commonly known as fluoroquinolone toxicity.
    Fluoroquinolone antibiotics ( Cipro , Levaquin Avelox etc ) inhibit the liver P450 enzyme pathway to varying degrees, the enzymes used to metabolise caffeine, therefore coffee ( & also the majority of drugs which enter the body ). This inhibition by fluoroquinolone antibiotics lasts for varying amounts of time & the timeline seems somewhat dependent on the severity of reaction.

    Having been severely damaged myself, prescribed these so called antibiotics many times before I realised what had really happened to me & why I was so very unwell, I now find I can no longer tolerate coffee at all, even in the smallest amounts. Coffee in any amount makes me feel extremely ill.
    For those of us who have been injured by these DNA mitochondrial damaging chemo drugs that masquerade as antibiotics, ( a situation known as floxed ) this is unfortunately a very common scenario.

    Many of us who are injured by fluoroquinolone ‘antibiotics ‘, find we now have another issue, as well as being intolerant to caffeine we often find we are also unable to tolerate various allopathic drugs, both those we might have taken with no noticeable problems whatsoever in the past before we were hit, & many of us also are finding the same issues with various allopathic drugs we might have no choice but to take in the future, depending on our own personal situation, the genetic implications etc as mentioned above etc, & on how the particular drug prescribed is metabolised.
    I personally have been in this situation for many years & I do often wonder if these enzymes will ever fully recover in my case, as I have not been able to tolerate any allopathic drug I have been prescribed since my most severe reaction, including other classes of antibiotics, I try very hard indeed now to avoid allopathic drugs when humanely possible.