In my last post, I reviewed some of the background on how and why cholesterol came to be viewed as a risk factor for heart disease, and how this creates a clinical conundrum for those who go on a low-carb diet and see a big rise in their LDL (the “bad”) cholesterol but see every other aspect of their health improve. I discussed how there is a paucity of research on this particular population of patients and, hence, a lot of controversy about this topic. Then I introduced the work of Dave Feldman, a software engineer and internet personality who has been leading a grass roots research effort into this very topic. And I reviewed how Dave has proposed that maybe – just possibly – the metabolism of people on low-carb/keto diets is so different from that of a person following a more typical diet that cholesterol simply doesn’t behave the same way in their bodies, and hence the research we have until now suggesting that high cholesterol is a risk factor for heart disease might not apply to them.
I’m going to spend the rest of this post discussing a fascinating study that Dave and his colleagues just published which attempts to shed some light on this question. But first, let me stress that all of this remains theoretical, and – spoiler alert – we still do not know if having severely high levels of cholesterol due to a low-carb/keto type of diet is safe. One study does not a fact make, and most doctors would advise continued caution in this area. And while I do feel that the obsession on cholesterol and its treatment has had some real downsides (by emphasizing a laser focus on this one risk factor, while far more important risk factors such as metabolic syndrome/insulin resistance get ignored), it’s only fair to admit that there are still many, many, papers out there showing that – on a population level – there is a strong link between elevated cholesterol and cardiovascular disease risk. Please keep that in mind as you read the rest of this.
And now onto the study.
After years of advocating, Dave Feldman was finally able to raise money via a crowdfunding effort and get a few medical doctors to agree to conduct an experiment. Led by Dr. Matt Budoff – a very well respected cardiologist at UCLA – they enrolled 100 patients who had been on low-carb/keto diets for about five years and who:
Had extremely high LDL cholesterol levels (think 300, 400, or 500, when most authorities recommend keeping this number to 100 or less)
Could prove that they did NOT have such high LDL levels before going low-carb (and hence that the rise in cholesterol for them had to be due to the low-carb diet)
Seemed to be otherwise metabolically healthy
Then they put these patients through a special type of CT scan that looks at the coronary arteries, documenting how much plaque, if any, they had in their arteries.
Next, they found a comparable group of patients enrolled in another study in Miami that is also scanning coronary arteries using the same type of CT scanner. These patients are NOT on a keto diet and do NOT have extremely high LDL cholesterol levels, but are in every other measurable way (blood pressure, smoking history, body mass index, HDL cholesterol, etc) similar.
The punchline? Most patients in both groups had no coronary plaque at all, and on average, there were no significant differences between the groups.
I cannot stress enough that this study does not definitively prove that keto diets are safe. The fact that the “control” group came from another study is a major limitation, as is the fact that the patients on average had only been on keto for about five years. Further research is needed – and more is coming.
Dave Feldman’s group plans to study their group of keto dieters by serially scanning them over the next several years to see if there is a change over time in how much plaque they form in their arteries. (Since we can never account for all the minute differences between individual people, following the same group of people over time and seeing what happens to them will ultimately be powerful evidence one way or the other).
But this is the first study I know of that has looked at the risks of high cholesterol in this specific population of patients who follow a low-carb diet. And at least so far, it’s somewhat encouraging. There were folks in the study who had EXTREMELY high levels of LDL cholesterol (over 500) and who were plaque free even after five years.
To put this into a final piece of context: I do not believe that keto diets are the best, or only, option for losing weight or becoming healthier. I have patients who are vegan – the polar opposite of keto – and doing great. As I’ve said before, I’m diet agnostic. The best diet is the one that works for you and that you can stick to most of the time.
With that said, I’ve had so many patients do great on keto over the years that, if it’s a safe diet to follow, it would be a shame to not have it in our toolbox of things to offer patients. Therefore I do believe that the work Dave and his group are doing is critically important, and hopefully will provide us with some much needed answers in the coming years.
Read the full study here – and note well that the mainstream media, which is quick to hype every poorly done trial that suggests you are about to drop dead if you aren’t living like a puritan, hasn’t said a peep about it.
