Cognitive Study with Bulletproof Coffee

Bulletproof Coffee drinkers! We have some exciting news for you!

There is an upcoming study on Bulletproof Coffee and we thought you would like to participate! Yoni Donner, Professor Stephen Kosslyn at Stanford University and Quantified-Mind, are studying the effects of Bulletproof coffee vs regular coffee on cognitive performance.

I’m assisting in recruiting participants for their coffee study. Participation is optional. For the first 100 people who complete the study, you will receive a free bag of Upgraded beans.

Edit:  When you submit the form, do not expect an e-mail confirmation.   An e-mail will be sent next week with further instructions on how to prepare the coffee and other information.

EDIT: In order for your results to be considered complete, you have to complete the study within the restrictions given to you by the researchers.  Make sure you do the two daily sessions at roughly the same time every day, and try not to miss any days. If you must skip days, make sure you don’t miss more than two sessions overall.

Before signing up for the study, please read the following:


Please read this form carefully before deciding whether to participate in this study.

Purpose of the study

This study will identify effects that “bulletproof coffee” has that are different from the cognitive effects of coffee alone. Bulletproof coffee is brewed with beans that are low in mycotoxins and biogenic amines and blended with grass-fed butter. While coffee alone is known to affect cognitive functions, we would like to examine the additional benefits that the special beans and butter added.

What you will do in this study

When you sign up, an e-mail will be sent to you with instructions about when to drink coffee* (this will be sent next week), the regimen and a participant code. You will need to purchase Starbucks Dark Roast coffee, Bulletproof Upgraded Coffee, and grass-fed butter. You will be sent a coupon code for 1 free bag of Upgraded coffee, including shipping if you are one of the first 100 to complete the study. To conduct the cognitive testing, you will be asked to sign up at the website On your “Tests” page, you will need to click “New Experiment” and enter your participant code to officially join the study. You will only need to do this once. You do not need to fill in any identifying details on the Quantified Mind site besides your email address for authentication purposes.

Once you have signed-up and used your participant code at Quantified Mind, you will need to pick a time of day to consume your coffee. You will have to test yourself twice: the first time 1 hour after consuming the coffee and the second time 3 hours later. For example, if you choose 9:00 a.m. as your coffee drinking time, you will have to test yourself once at 10:00 a.m. and again at 12:00 p.m. Additionally, you will need to pick a way to brew your coffee. This is important because you will need to brew your coffee the same way throughout the study.

To test yourself, brew a cup of coffee following the coffee consumption regimen. 1 hour later, log in to and complete the “Bulletproof Coffee Study” on your “Tests” page. 3 hours later, repeat the aforementioned procedure. The tests should take 10 minutes each, for 20 minutes total. Before taking each of the tests you will be given a chance to practice as much as you like.

You will repeat the procedure described above on 8 separate days, following your coffee consumption regimen. The first 100 people to successfully complete the 8 test sessions, will receive a coupon for a free bag of Upgraded Coffee, including shipping.

You will have the opportunity to ask the investigators questions about the study, both during the study and after its completion.


There are no anticipated risks associated with participating in this study; the benefits are: (1) a description of our research and hypotheses at the end of your participation; (2) learning about your own cognitive response to bulletproof coffee; and (3) a free bag of upgraded coffee if you are one of the first 100 people to complete the study.


Your participation in this study will remain confidential, and your identity will only be stored in a secure machine together with the data, and will not be revealed to the investigators or anyone else. The data will be analyzed anonymously and in aggregate.

Participation and withdrawal

Your participation in this study is completely voluntary, and you may withdraw at any time without penalty by simply informing the investigator that you no longer wish to participate.


This research is being conducted by Yoni Donner and Professor Stephen Kosslyn, Stanford University, 75 Alta Road, Stanford, CA 94305. If you have any questions, please email

Whom to contact about your rights in this research, for questions, concerns, suggestions, or complaints that are not being addressed by the researcher, or research-related harm: Michelle Bayly, PhD, Human Subjects Coordinator, Department of Psychology, 450 Serra Mall, Jordan Hall, Bldg 420, Room 100, Stanford,CA 94305-2130. Phone: (650) 736-9993.


Sign-Up Form

44 thoughts on “Cognitive Study with Bulletproof Coffee”

  1. Could you maybe write a few words on why you’re not doing a study on something that you so strongly believe in (mycotoxins and their detrimental effect on mental performance) double blind? Is it not worth the effort to get some conclusive data?

      • To me it seems unaffordable to waste money on a study that will suffer from so many egregious epistemological flaws that nothing will be learned.

        • I respect your opinion but do not share it. You can of course drink Starbucks, which doesn’t have these studies, but the truth is that most people can feel the difference between my clean coffee and Starbucks even without a double blind study to help them trust their own judgment… ?

  2. Are there any particular dates that the study has to be conducted on? My morning schedule and availability can vary based on meetings and summer vacation so I want to be sure I can be a good participant before signing up. Thanks!

    • Just make sure you complete all the days. You can start anytime, but some planning may help to ensure that you don’t miss more than 2 days.

  3. David I’ve always been a huge fan of the coffee but it seems very un-scientific to get a bunch of people who you know are already fans to be the participants and then give them a carrot stick of the very thing that you’re trying to get an independent evaluation on!

    Too much influence there leaning towards a positive outcome and leaving yourself with gaping holes when sceptics want to chime in… unless of course I’m not aware of a whole other part of the experiment, in which case, go David!!

    • It’s not a blinded study but it’s statistically valid. Either they will or won’t have quantifiably improved cognitive performance. Study design was reviewed by a well respected stanford prof.
      This goes far beyond what any other coffee company has done in this space!

      • I sent an e-mail to prof. Kosslyn, this was his response:
        “From what I gather about the Bulletproof study, you are correct. It is not blind at all, and the effect could just be placebo.

        I have never endorsed this study or hinted that the design is appropriate. From what I’ve been told, it will be difficult to infer much from the results.

        I’ve forwarded this to Dave but no response. Why are you referring to this study as ‘their’ study, when they don’t even endorse the study design?

        • Dave, can you please debunk this if it’s not true? I’m getting pretty excited about the work you’re doing and its potential, but that’s a pretty damning statement about your study and undermines your credibility if true…

  4. In this blog it is written – When you sign up, you will be given a coffee consumption regimen and a participant code.

    I filled out the form.

    How long until the regimen will be sent?

    Thank you,

  5. Are participants allowed to eat breakfast with the coffee or does it have to be just bulletproof coffee? I exercise in the morning so I eat food with my coffee

  6. Sounds like an excellent idea Dave and I hope for some good results. I would love to partake as I already own upgraded coffee and about 25 bars of Kerry’s Gold butter, but my job won’t allow me to run this type of schedule. Can’t wait to see the end results and best of luck.

  7. Do they restrict the way the coffee is brewed, and wouldn’t that effect the study? For example, cold brewing with a French press or hot toddy cold brew system is supposed to be the healthiest method of making coffee. I just purchased a French press myself with the intention of trying this method.

      • Why do you see hot french press as superior? I ask because I have switched to cold-brewing for convenience, since it is easier for me to stock my fridge at work with concentrate and heat up a cup of coffee in the microwave to then make my BPC.

  8. There should be 5 conditions in this study: 1) Starbucks, no butter; 2) Starbucks w/ butter; 3) Bulletproof coffee, no butter; 4) Bulletproof coffee w/ butter; and 5) no coffee consumption to establish a baseline. And, as you mentioned, researchers should be assigning the bags unmarked to participants and they should know which bags are getting assigned to whom.

    • I’d add one more group to the study: People taking caffeine pills.

      Also, that group and the “no coffee” control group should still get bags of stuff that *looks* like coffee and has to be prepared like coffee.

      Of course, you run into problems of taste between all the groups, such that people would be able to figure out which group they were in…

      So, what you do is add harmless stuff to all the brews that makes ALL the concoctions taste like crap–and definitely not like coffee. That will mask the controls effectively.

      Certainly Dave isn’t arguing that it’s the taste that makes you smarter?

    • Yes, but only in the left eye. ?

      Honestly, that would be awesome if you blinded yourself for this study. There is another study with blinding done on decaf vs caf, also using the toolset.

    • It sounds like you’ll have someone else make the coffee to the instructions, but not know yourself which coffee you are getting?

  9. You could have easily blinded this by creating a “study coffee” in your shop with a prize of (standard coffee + bulletproof coffee)/2 and randomly assign buyers to one of the two brands of coffee.
    If you measured physiological instead of psychological variables (ie blood tests), then non-blinding would be perfectly fine for me.

  10. I would like to participate in the study but I would only be able to drink the coffee after I got off work around 5pm. I think that might be too late in the day to get sufficient sleep. I get up for work at 4:15am. What are your thoughts? How long in the evening is Bullet Proof coffee going to keep me running in high gear? I tried this once at 7:30pm because it sounded good but I had a horrible nights sleep.

    • Coffee after 5pm is pretty tough. You could probably do the study but not sleep that much. Recommend not losing sleep over it. ?

      • Thanks, I get about 5 to 6 hours of sleep I really need the coffee first thing. I just can’t swing the testing part while I am at work. I might have to try a bulletproof coffee at 5pm and see what happens. I probably wait until Friday night in case it doesn’t go well. 🙂

  11. I’ve been looking over the protocol at the QM site and I have a few questions.

    1) When I make butter coffee I use 4 tbsp butter in 16 oz water (actually a little less to make room for the water content of the butter). The protocol calls for 2 tbsp. Is 4 tbsp acceptable?

    2) I also add MCT oil, cinnamon, and dark chocolate. Should I leave these out during the experiment run?

    3) By ‘Regular’ coffee, you mean the Starbucks Dark Roast? I’m using Sumatra, FWIW.

  12. How about a coupon to take a bit of the cost down for the Upgraded Beans? With shipping even the 5lb bag comes out to just under $20/lb

  13. I’m signed up to participate in this study, but the IT policy at work will not allow the installation of non-approved software. My current verson of IE at work doesn’t work for the tests.

  14. How would you recommend we grind the coffee? I would imagine that having it ground at the store would contaminate it with non-BP coffee?

  15. Ok, finished it today! Kinda feel like I got better at taking the tests everyday, so hopefully it’s graded on a curve. Hopefully I’m in the first 100. Thanks!

  16. Dave,
    I am a 20 year old college student and would love to participate in this study. Your bulletproof coffee/ high fat diet/intermittent fasting has given me control over my brain and an edge in everyday life, and I would love to quantify this. Please choose me! haha

  17. I would love to participate in this study but we are having a hard time finding grass fed butter on Vancouver Island..we’ve just been using coconut oil and MCT oil for our bulletproof coffee. Would coconut oil be ok instead of grass fed butter for the study ?
    Love your podcast by the way!


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