**EP43: Small Dense And Light Fluffy Particles**
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Hi, my name's Dr. Warwick Bishop, and I'd like to welcome you to my consulting room. Today, I'd like to share with you a little bit from one of the meetings I went to in June of this year. Back on the 26th and 27th of June, I attended the European Atherosclerosis Society road trip, which was held in Brisbane. We had some absolute world-class speakers there, coming from different parts of Europe, the UK, etc. It was a real feast on up-to-date lipidology and some of the science behind it.
Now, most of you may be aware that I'm pretty supportive of this concept of particle size and very interested in the distinction between large fluffy particles versus small dense particles when we're talking about the LDL cholesterol moiety. So, what's that story about? Well, there's lots of stuff on social media saying that if you can get rid of your small dense particles and just have large fluffy particles, then your risk of a coronary event should be dramatically reduced. The reasoning is that the large fluffy particles are bigger and therefore do not go through the endothelial pores and get into the intima, or the inside coat of the blood vessel.
What I'd like to share with you is something that was presented at this meeting, which I thought was really interesting. I'm not going to promise these numbers are exact; I scribbled them down and I'm happy to go back and review them if someone wants to point that out to me. But this is roughly what I took away: the endothelial pores are approximately 70 microns in diameter, while the large fluffy particles are about 50 microns in diameter. So, if you like, there's a little bit of wriggle room on each side—maybe 10 microns for one of those particles to get through.
The small dense particles, however, are 40 microns. They've now got 15 microns around them to squeeze through that pore. I thought the differentiation or the distinction between large and small would be considerably more than about 10 microns. I spoke with one of the presenters about this afterwards because, to me, the difference between a 50 micron diameter and a 40 micron diameter with a 70 micron hole doesn't sound that much.
The difference is not really in that diameter size, but in the density. Remember that the difference in density is directly related to the radius cubed. So we're talking about a change in density related to the difference in radius to the power of three. It is that power of three that makes a big, big difference to the density of the particle.
Now, the importance here, as far as I can tell, is that the actual diameter or what's presented to the endothelial pore—the hole in the artery—is not a great deal different, although the particles are quite different in their density. I thought this was really interesting and certainly serves as a reminder or makes us question whether just large fluffy versus small dense is the whole story, and I'm pretty sure it probably isn't.
I think it's useful, but I don't think it's absolutely the major driver. What I would say, though, is that I'm still very supportive of people having large, fluffy LDL cholesterol because we see that in environments where there's less insulin, where there are lower triglycerides, and where normally the HDL is coming up as well.
So, the environment or the metabolism or the metabolic profile that's present when large fluffy particles are present is certainly more desirable. We know if you can get your triglyceride levels under about 1.1 to 1.3 millimoles per liter, then you pretty well negate small dense particles and move over to large fluffy particles. The same sort of changes in lowering triglycerides will raise HDL levels, and all that is a better picture overall.
So, don't get me wrong; I think large fluffy is good and small dense is bad. But I think in terms of the size being the determinant of what gets into the arteries, I think it's far more complicated than that. Because the difference is only 10 microns for these particles to get into a pore or a hole in the artery that's 70 microns, I don't think that is going to be the biggest determinant of the outcome in individuals.
Well, I hope you find that interesting. Keep working on your large, fluffy particles. Keep your carbohydrate exposure down because carbohydrate drives insulin, and insulin almost certainly drives small dense LDL cholesterol. Insulin in excess also lowers HDL cholesterol and raises triglycerides. So for those people who are sensitive to carbohydrates, please keep them down and work on your large fluffy particles.
I thought you might find that a little bit of interesting information, particularly on the sizes and their relative sizes versus the densities.
All right, enough on LDL particle size and density. I wish you the very best. Thank you for joining me, and good health. Goodbye.
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