I began my original butter experiment without a hypothesis about the effects of butter on cholesterol. I was tracking blood lipids so that I could identify any possible adverse reactions. After initially seeing a positive change, the numbers started to go the wrong way, with HDL dropping and non-HDL going up. At the same time, I had switched from the Kerrygold butter I usually used to a local brand from my farmer's market. It was supposed to be "100% grass fed," but it did not have the deep yellow hue of the Kerrygold, so I suspected it could be responsible for the adverse results. After a day or two using an Icelandic brand (Smjor), I decided for the remainder of the experiment to test only Kerrygold butter. A few days after the switch back, the numbers moved back in the positive direction. I tracked for a few more weeks and then reported my initial results here.
After the
original post, I spent about three more weeks on the same diet (1/2 stick of Kerrygold butter per day), followed by three weeks of butter elimination (during this elimination phase, there was some increase in coconut oil as a partial substitute for the butter calories). Finally, I went back on a high-butter diet for an additional five weeks. During this last phase I decided to double down and eat a full stick of Kerrygold butter every day (about 112 grams of butter and 90 grams of fat). The diets were otherwise similar, though I was likely consuming more total calories during the high-butter phases. Data points were generally taken weekly, on Sunday afternoons (not fasted, but I don't believe it makes much difference, since I am not measuring triglycerides).
Based on the additional data I can report that the addition of butter to my diet may have increased my HDL cholesterol. However, it has not had a convincing long-term effect on my non-HDL cholesterol. The HDL remains elevated from before, but non-HDL readings are consistent with my average numbers over the past three years or so. My working hypothesis at this point is that the change in non-HDL I observed originally was a temporary disturbance of homeostasis. This may have been due to the butter or to another unknown cause.
I also believe this data suggests that different brands of butter can have different effects on cholesterol values. I will show this data below, though given the design of this experiment, I will not be able to prove it without a follow-up experiment. However, I am satisfied with my original concern, which is that the addition of a good brand of butter to my diet does not seem to have any measurable adverse effect on cholesterol measurements.
Results
The additional data points are shown in the two plots below.
The four green points show the data that was dropped from the original data set because I was not using Kerrygold butter. The last five points are for the latest diet where I am eating a full stick of butter per day.
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| HDL measurements over time. Red points indicate control. Blue and green points indicate experimental group with consumption of at least 0.5 sticks of butter per day for at least 7 days prior to testing (blue=Kerrygold). No statistically significant difference in control vs. experimental measurements when green points are included. Trend line is for red points only. |
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| Non-HDL cholesterol over time. No statistically significant difference between control vs. experimental measurements when green points are included. Trend line is for red points only. |
The next two plots show the same data, zoomed in to show points from the beginning of the original butter experiment to the present time. The three red points are the latest butter-elimination phase.
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| Trend line for blue points. |
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| Trend line for blue points. |
Overall, I think there is some basis for concluding that added butter is having a positive effect on HDL, although the results are not statistically significant when the green points are included. However, it is also possible that some other factor is concurrently causing my HDL to increase.
The trend towards positive HDL outliers has continued in the butter dataset and is especially strong in the latest readings where a full stick per day is consumed, suggesting a dose-response relationship. My last three readings are all greater than 100, which is the meter's measurement limit for HDL cholesterol. Since I am computing non-HDL cholesterol as Total minus HDL, this measurement limitation will inflate the non-HDL points by an indeterminate amount at the same time as it underestimates HDL. The highest reading ever recorded in the control dataset is 83, while the butter dataset has 5 readings above that level and three above 100.
The non-HDL numbers do look like noise at this point, except for the original cluster of low readings when the original butter experiment began. There probably was some underlying cause for that, though it is clear to me that if the butter had anything to do with it, the effect was temporary.
Note also that there are several negative outliers for HDL in the non-Kerrygold butter set. This suggests that different brands of butter can have different effects on cholesterol measurements. This phenomenon may warrant further study.
What's the Take Away?
Okay, I hear what you're saying: "Greg, that's a heck of a lot of colored dots. So what?" I think the bottom line is, I'm eating a whole stick of butter every day and my lipid profile has either stayed the same or gotten a little better. Works for me.
Measurement Accuracy
During this experiment, I observed that the
CardioChek PA seems to be very accurate at measuring HDL, but much less accurate at measuring total (and therefore non-HDL) cholesterol. One of the newly collected data points shown above is the result of a VAP cholesterol panel ordered by my doctor. The same morning as the blood draw for that test, I took three successive readings of HDL and total cholesterol with the CardioChek PA. The VAP test showed an HDL of 68 and non-HDL of 233. The three HDL measurements on the CardioChek PA averaged out to 68, same as the VAP result, with a standard deviation of only 1.7%. For non-HDL, on the other hand, the average was 191 with a standard deviation of 15%. Compared to the 233 non-HDL measured by VAP, the CardioChek PA was off by 18% even when three separate measurements were averaged.
Therefore, variance seen in my HDL readings over time suggests that real changes are taking place in my body. However, variance in my non-HDL measurements will be substantially the result of measurement error in addition to physiological changes. To put this in perspective, the standard deviation of all of my non-HDL measurements over the last 2+ years taken together is only 15.8%, barely higher than the meter's built-in measurement noise.
The CardioChek also sells test strips for
direct LDL measurement. I will probably check those out at some point, as they may prove to be more accurate than the total cholesterol strips.
Next Steps
Ideally, self-experimentation would be based on biomarkers that can be measured accurately and cheaply, and that quickly reflect real health trends. Blood sugar measurements are very useful in that regard, because it only takes one finger prick an hour after a meal to obtain useful information about your body's response to carbohydrates.
Over the course of this experiment, I've become skeptical of the value of cholesterol measurements as a target of self-experimentation. Given the meter's built-in measurement noise and the long half-life of circulating lipoproteins, it takes weeks or months for changes to be clearly evident. That makes it difficult to do useful experiments.
My most pressing health goal until the end of 2012 is a
405 pound deadlift. High
cholesterol and extra calories from butter are probably going to help me achieve that goal, so I will be putting my cholesterol investigations on hold for the time being. In the mean time I do have a few other experiments to report on, so stay tuned.
