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. 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.

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?”

Now I’d like to hear from you. How do you respond to coffee and caffeine? Do you know whether you’re a fast or slow metabolizer? If not, what do you suspect? Let me know in the comments section.

177 Comments

Join the conversation

  1. Chris –
    You didn’t really get into whether we should use paper filters or no filters. My understanding is that paper filters remove the terpenes which give the cognitive boost but may raise LDL. Do we want to consume the terpenes or filter it out? Is it true that fats like MCT oil and butter help the terpenes cross the blood-brain barrier?

    Also, which roast is healthier: dark or light? From my research, I found dark roast coffee, such as French or Italian Roast, or roasts used to make espresso or Turkish coffee, are typically higher in neuroprotective agents. One study in Molecular Nutrition & Food Research (http://www.greenmedinfo.com/article/roasted-coffee-much-higher-neuroprotective-lipophilic-antioxidants-green-coffee) found that dark roast coffee restored blood levels of the antioxidants vitamin E and glutathione more effectively than light roast coffee. The dark roast also led to a significant body weight reduction in pre-obese volunteers, whereas the lighter roast did not. Another study (http://pubs.acs.org/doi/abs/10.1021/jf904493f?journalCode=jafcau) showed that dark roast coffee produces more of a chemical that helps prevent your stomach from producing excess acid, so darker roast coffee may be easier on your stomach than lighter roast coffee.

    So, is dark roast healthier?

    • What are your thoughts on Purity coffee? It seems to be one of the healthiest coffees on the market. They tested their beans against 49 other coffees, including Bulletproof coffee, and they were the highest in antioxidants and lowest in toxins. They apparently tested for 60 different mold toxins and contained zero detectable levels of these molds.

      If anyone is interested in testing Purity out, I used code EVOLVEDNS for 30 % off ($62 for the 5lb bag).

      I notice a difference in how I feel after drinking it (energy levels are very stable) and am able to drink it black. I’m wondering if it is because it’s higher quality or just placebo effect. Their decaf and pods are really good too.

  2. What about the non-dietary/ nutritional aspects of coffee?

    I ‘cured’ myself of my year-long daily GERD (severe reflux) through much trial and error, super strict diets (fish, hemp protein, sweet potatoes, olive oil, broccoli sprouts) … countless supplements, etc.

    What actually worked turned out to be a certain kind of probiotics (cough Garden of Life) – though I’m sure there are similar ones out there, just compare the strains on the back. At least I think that helped, who knows.

    Anyway back to coffee … that was one of the few consumables GUARANTEED to trigger my GERD back in the day (I can drink it fine now, though am trying to get off it again).

    Coffee was worse than alcohol, fried food, hot peppers (actually spicy/ capsaicin food had no effect despite common knowledge). My biggest triggers were coffee and refried beans (my GERD was related to intestinal gas somehow, either a cause or compounding symptom).

    It’s extremely acidic on the teeth and in the stomach in general. I can’t speak necessarily to throwing acidic food in the stomach, I’m not sure it would appreciably raise the actual pH of the large highly acidic stomach acid. In fact adding HCl digestive aids might help GERD in some cases. But coffee seemed to wreak havoc on my system when I was in this sick “GERD” state (I was never overweight either, oddly enough, that was not a cause — 6 feet 170).

    Now that I’m healthy, have rebalanced gut flora … coffee does not wreak any havoc, other than being a laxative of course. But it seems the potential is there. There seem to be some unique properties to coffee, moreso than just caffeine. Anyone susceptible to reflux is wise to steer very clear of it.

  3. I read this article (http://bit.ly/2hF2kx5) and was inspired to quit drinking coffee after learning it is depleting the magnesium in my already magnesium deficient body. I can’t tell you enough the tremendous results I gained by avoiding this substance which does more harm than good.

  4. I think coffee doesn’t make a bad affect on me, or it may take a long time to see the result. Thank you for the post. For me, because I’m not a coffee lovers, but I will drink when I need to work and choose another drinks when I don’t need them.

  5. Very surprised to learn I’m a fast metabolizer. I wonder if that is related to my high sensitivity to medications? I usually need a much smaller dose than recommended for someone my age and size.

  6. Chris, you’ve talked about coffee quite a bit now but i don’t recall you mentioning the concern around mineral depletion and absorption, which is surprising considering how much you bang on about nutrient density and absorption.

  7. I think moderation is key. I know plenty of people who have become dependent on caffeine to make it through the day. It’s a bad idea to get your body to the point that it relies on a stimulant. Lucky for me, I despise the taste of coffee so I’ve never had to worry about it!

  8. I love coffee. It took me a year to get off of it when I was going through health coach training. Now I am back on and realizing I want back off. Tea is just not coffee, but my personality is very different on tea vs. coffee,,,,,,meaning tea= more calm, coffee= more frantic and energetic (which I like–I could build a pyramid). I CANNOT drink coffee in the late afternoon or evening or it will disrupt my sleep.! I love coffee and I hate it. (plus once I have a cup, I want another)!

  9. I have never been a coffee fan and honestly I don’t understand why so many people are addicted to it. I don’t mind having a cup occasionally, but what I’d really love is a cup of hot green tea with a spoon of honey! That has become my healthy addition.

  10. I tested as a fast caffeine metabolizer. If I drink late in the day, it does make me sleepy but not like alcohol. Alcohol knocks me out–best way for me to sleep. I can feel my glucose levels decrease whenever I drink coffee or eat chocolate. I don’t need coffee like other people, but I do occasionally drink it. For sure, I can feel its effects. I drink it for its taste and antioxidants, not for stimulant effect. Nikola Tesla considered stimulants including caffeine bad for your health, and he was extremely smart. It’s possible he was a slow caffeine metabolizer and could sense its effects.

  11. Hi Chris,
    Thanks for explaining how to check to see what category we fit into. I understand the caffeine is the kicker in this, but what about teas? How do they fit in with the coffee?

  12. Interesting topic. I went cold turkey and quit coffee in 2012. I was drinking 2 to 3 cups of coffee daily with a lot of added milk and sugar, which increased my weight. I was also drinking at least 2 Diet Cokes daily which combined with the coffee would sometimes make me jittery. Caffeine can affect your central nervous system over time.

  13. Chris,
    Very interesting, as always! When you sent your genetic data to your friend, I hope she sent it back! I’d hate to lose that. 😉

    As for my coffee habits, I seem to be just like you – really sensitive. I backed it off to just one cup per day in the morning, made in a nice vacuum pot. If I have a cup past 3PM, I may be in for it.

    I know someone who absolutely insisted on drinking coffee right up to bedtime. She did indeed fall asleep, but in her chair, and would wake up repeatedly through the night, and wouldn’t have the strength (or lucidity) to actually get to bed. I explained that cutting out the coffee may greatly benefit her sleep, She shut that conversation down right quick. Oh well.

    Dave

  14. Hi Chris,
    Thank you for show us this research tool for 23 and me. When I looked at my “caffeine consumption report” on 23andme it states that I am more likely to consume more caffeine than others (9 mg more). How is this possible if I am a slow metabolizer (my results showed C/C). Wouldn’t someone who metabolizes caffeine slowly tend to drink less than the average person? I drink mostly Swiss water processed decaf now b/c regular consumption left me with headaches when I didn’t drink it daily and then monthly migraines around my period. It seems like the caffeine report contradicts what my gene variant data shows.

    Also, to get to the report you go under Tools, then scroll down to browse Raw Data. There isn’t a my account tab anymore.

  15. A word of caution about coffee. I don’t have the references to hand any more but when I was researching neuroprotective agents last year I found many articles through Google Scholar which made it clear that, although neuroprotective for men, coffee consumption was not so for women – quite the contrary in fact – at least post-menopause. Worth checking.
    For myself, I love everything about coffee but sadly it doesn’t love me. Incidentally, when I was pregnant the smell alone would make me feel quite ill. Worth listening to your body I think!

    • Oh wow, me too! That is how I always knew I was pregnant. I love coffee and I am down to one cup a day, I drink only organic. Anything over that 1 cup and I feel terrible for hours. I know I need to get off it but I have to have sharp focus at work. Retirement is coming soon so I think then I can get rid of it then.

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