Results of The Buttermind Experiment

In August, at a Quantified Self meeting in San Jose, I told how butter apparently improved my brain function. When I started eating a half-stick of butter every day, I suddenly got faster at arithmetic. During the question period, Greg Biggers of proposed a study to see if what I’d found was true for other people.

Eri Gentry, also of, organized an experiment to measure the effect of butter and coconut oil on arithmetic speed. Forty-five people signed up. The experiment lasted three weeks (October 23-November 12). On each day of the experiment, the participants took an online arithmetic test that resembled mine.

The participants were randomly assigned to one of three groups: Butter, Coconut Oil, or Neither. The three weeks were divided into three one-week phases. During Phase 1 (baseline), the participants ate normally. During Phase 2 (treatment), the Butter participants added 4 tablespoons of butter (half a stick of butter) each day to their usual diet. The Coconut-Oil participants added 4 tablespoons of coconut oil each day to their usual diet. The Neither participants continued to eat normally. During Phase 3 (baseline), all participants ate normally.

After the experiment was finished. Eri reduced the data set to participants who had done at least 10 days of testing. Then she made the data available. I wanted to compute difference scores (Phase 2 MINUS average of Phases 1 and 3) so I eliminated someone who had no Phase 3 data. I also eliminated four days where the treatment was wrong (e.g., in the sequence N N N N N B B N N B, where N = Neither and B = Butter, I eliminated the final Butter day). That left 27 participants and a total of 443 days of data.

Because the scores on individual problems were close to symmetric on a log scale, I worked with log solution times. I computed a mean for each day for each participant and then a mean for each phase for each participant.

2011-01-26 buttermind averagesThis figure shows the means for each phase and group. The downward slopes show the effect of practice. The separation between the lines shows that individual differences are large. (There was no reliable difference between the three groups during Phase 1.)

The point of the baseline/treatment/baseline design is allow for a large practice effect and large individual differences. It allows a treatment effect to be computed for each participant by computing a difference score: Phase 2 MINUS average of Phases 1 and 3. The average of Phases 1 and 3 estimates what the results would be if the treatment made no difference.

2011-01-29 buttermind difference scores

This graph shows the difference scores. There are clear differences by group. A Wilcoxon test comparing the Butter and Neither groups gives one-tailed p = 0.006.

The results support my idea that butter improves brain function. They also suggest that coconut oil does not. In another post I’ll discuss what else I learned from this experiment.

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30 Responses to Results of The Buttermind Experiment

  1. Thomas Johnson says:

    Great job expanding the experiment!

    Can you elaborate on what “There was no reliable difference between the three groups during Phase 1″ means?

    Can you please provide the raw data so others can conduct statistical analysis?

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  3. Eri Gentry says:

    Thanks for the analysis, Seth. :)

    @Thomas: During Phase 1, all participants were essentially equal, meaning they had simply enrolled in the study and been asked to take the math test every day. Participants were not selected to be in the Butter, Coconut oil, or Control groups until the end of Phase 1, so during Phase 1, “there was no reliable difference.” Hope that makes sense!


  4. Seth Roberts says:

    The raw data is available here:

    By “no reliable difference during Phase 1″ I meant I did a one-way ANOVA (factor = group) on the data from Phase 1 and found no reliable difference (p = about 0.2) between the three groups.

  5. August says:

    Did the participants use the same kind of butter? Will some cheap store brand suffice (as long as it’s really butter!) or do we need something more to get the effect?

  6. Seth Roberts says:

    August, I don’t know what brand of butter the participants used. As far as I know, they were not told what band to use. For a long time I used Straus butter. I cannot get Straus butter in China, so after using up the six pounds I brought with me I switched to two butters I could get here, Landolakes (made in USA) and a New Zealand brand. I didn’t notice any change.

  7. Kevin Burton says:

    I’m sure this is the fat in the butter and coconut oil.

    Interestingly enough, these are both saturated fats.

    Would be interesting to do another experiment with unsaturated (mono+poly) fats.

    I supplement and control my diet for health reasons. I haven’t yet optimized it for mental computation reasons.

    Interesting area to move forward.

    Also, I like the use of the web to test these hypothesis.

  8. Kevin Burton says:

    Also, another idea would be to double blind both researcher and participant.

    Since coconut and butter have a flavor this might be a bit hard ….. Maybe some type of saturated flat without much flavor?

  9. Kevin Burton says:

    Ah…. mea culpa. I got the numbers wrong and misread the colors. :-P

    I now see that coconut oil as WORSE …. What is that about? Hm.

  10. Seth Roberts says:

    I see that the boxplot graph could have been clearer. Lower scores = faster = better. The Butter group was the fastest. The other two groups are about the same.

  11. Thanks for the analysis. I appreciated your explanation of why do an ABA (if that’s the right name) and seeing the corresponding analysis.

    On my own I did not realize there was more to see from the Butter Mind trial, so I am glad you did this.

  12. Kevin Burton says:

    Also, seems like one could rule out the additional caloric load since coconut oil has about the same load.

    And also rule out saturated fat since they both have saturated fat.

    Probably need to do a double blinded study with a larger group to actually have better results.

  13. Seth Roberts says:

    “Rule out saturated fat since they both have saturated fat.” Butter and coconut oil have quite different saturated fats. Saturated fats differ in the number of carbon atoms. For example, coconut oil is high in lauric acid (12 carbon atoms), butter is low. According to the Wikipedia article on saturated fats, the fat in coconut oil is 47% lauric acid; the fat in butter is 3% lauric acid. When I noticed a big improvement due to butter, I was comparing it to pork fat — which is also high in saturated fat. So I think we can narrow down the beneficial fats to those that are higher in butter than in pork fat or coconut oil.

  14. Matthew Cornell says:

    Thanks so much for the analysis, Seth, and for the experiment itself, Eri.
    @Michael re: ABA: I gave a very brief intro here, FYI, under “Know the type of your design”: Designing good experiments: Some mistakes and lessons

  15. I’m a big fan of butter and other quality fats.

    Any particular reason for choosing the week-based timeline? For example, why not two weeks (or more!) of butter? Perhaps there’d be a stronger signal.

    Also, I’m curious how much of the decrease in phase 3 for butter is because of practice vs. butter continuing to have beneficial effects after discontinuing consumption.

    And finally, I’d be curious to know if there are differences in raw vs. cooked, or pastured vs. organic vs. uh… cheap butter. Or cultured vs. non-cultured.

    And then there’s the question of whether this performance improvement generalizes to other types of mental tasks, like creative problem solving tasks.

    Thanks for writing this up!

    • Bryan Lundeen says:

      I agree with Marcel, more than a week is needed to get the minimum 30 values from each participant.

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  18. Bryan Lundeen says:

    I would really like to see what improvements can be made to a more generalized test of intelligence. Mathematic comprehension, spacial comprehension, language, etc. As an experimental psychologist, why did Seth choose a math test?

    Maybe just some simple tests like playing concentration and tetris computer games would be a better test?

    • Seth Roberts says:

      I used an arithmetic test for several reasons. 1. Tim Lundeen had used a similar test and found differences due to fish oil. 2. I already knew the answers quite well (e.g., I knew that 4 + 3 = 7). Less learning would be required than with a task where I had to learn the answers from scratch. 3. Portable. I could do the test anywhere, needed only a laptop. 4. Many separate trials. Each trial produces one number (a reaction time). Computer games such as Tetris can’t be easily broken into a series of trials. It’s crucial to have many separate measurements, rather than one overall measurement, to get an idea of variability. Also, with many trials, if one trial is bad (e.g., interruption) it doesn’t ruin the whole thing.

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  20. Bharath says:

    Interesting. If anybody replicates this experiment I would be interested in if someone other the participants added (or excluded) the butter. Having the participants add the butter could contribute to a strong placebo effect. If the results are due to placebo effect then I can think of many placebos that would reduce the potentially detrimental effects of eating 15 sticks of butter each month.

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  23. Dennis says:

    Real Butter is for Real! A must read is a book “The Hidden Story of Cancer” by Brain Peskin. In the book, Brian reviews the incredible research by Otto Warburg (over 60 years of active research) who was awarded a Noble Prize for his work and voted for another. In addition, three of his students went on to be awarded Noble Prizes for their individual works, including Krebs known for the universally accepted Kreb’s Cycle. Enough for establishing credibility.

    The reason for real butter is that it contains essential fatty acids, especially omega 6 (actually the body requires more of this than O3) and because of the emphasis on O3, the ratio is skewed to leave a deficiency in O6. The significance is that these EFAs are critical to “blood thinning and movement”, RBC proliferation, greater delivery of Oxygen to cells and increased cell absorption of oxygen. If you read this book, it will document repressed research by Warburg and show that cancer is the result of high carbohydrates, which lack EFAs O6 and O3. In other words, cancer develops from the breakdown of sugar resulting in an anaerobic environment, which is where cancer thrives.

    You will read how research (driven by big pharma) is on the wrong path for curing cancer. It is not genetic and it is not viral (as a primary cause). It is the result of excess sugar, glycolysis, lactic acid by-product, anaerobic environment and growth of cancer cells. Our body craves oxygen as its source of energy, which provides it efficiently, leaving an aerobic environment, and by products of CO2 and water. The more carbs we eat, the more lactic acid and anaerobic cellular environment and resulting cancer growth.

    Enjoy your butter and read this amazing documenting text on cancer research. You will find many recommendations for enjoying grass fed beef (as opposed to grain fed) and other “no no’s” we have been told to follow.

  24. Reini Urban says:

    And what about Sugar and Coffee? I seriously need that also for thinking.

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  28. tash says:

    know this is old but would the vitamin A make a difference somehow?

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