Intro to Lipids & Lipoproteins: Why there is no ‘bad’ or ‘good’ cholesterol | Peter Attia, M.D.

so i recently posted something on social media about uh my frustration with the way that the press uh and frankly even sometimes the medical establishment writes about cholesterol referring to good cholesterol and bad cholesterol now if you've ever listened to me on podcasts you understand that i talk about this in in great detail but a number of the comments suggested that there are a lot of people that are kind of new to this discussion they haven't necessarily followed me they certainly haven't heard the i don't know literally 25 hours worth of content on cholesterol over

the last four years on my podcast and they were kind of looking for a little bit of you know call it the tldr version of cholesterol and i thought this was a great excuse to do it so if you want to understand why i you know wail on people when they say bad cholesterol and good cholesterol you have to really understand what cholesterol is and why that type of imprecise language is unhelpful to put it mildly okay so let's take a step back what is cholesterol so cholesterol is a lipid it is synthesized by every

cell in our body that means every cell in our body makes cholesterol okay so why do we make this stuff well this stuff is super important or every cell in our body wouldn't make it it's essential for the creation of a cell so a cell you know when you look at cells when you look at a picture of a cell in a you know in a book or online or something they look like two-dimensional structures right they're sort of these flat things but really that's not what cells look like that's kind of a cut open

cell projected onto 2d the reality is cells are three-dimensional and they are fluid right they have to be able to be more than just perfectly open spheres so what gives them that fluidity is their membranes and it's the cholesterol within the membrane that provides that fluidity it's also what allows transporters to go across the surface of cells these transporters are what allow various things like glucose ions hormones etc to traverse cell membranes so it's important to understand that if we didn't have cholesterol we wouldn't have cells if we didn't have cells i wouldn't be making

this video and you wouldn't be here to watch this video okay no cholesterol equals no life full stop there are things that are almost equally essential for life that go beyond that cholesterol is the precursor to some of the most important hormones in our body which ranges from things like vitamin d to cortisol to estrogen to testosterone progesterone etc it's also essential for bile acids we wouldn't be able to digest most of our food without bile acids especially fatty foods so the list goes on and on as to why cholesterol is essential okay so why

does the story not end there why are we having this discussion well when it comes to something as essential as cholesterol not every cell in the body is capable of making enough cholesterol to meet its individual needs so the body has to be able to traffic cholesterol so there are certain cells that tend to be net exporters of cholesterol the liver for example as a general rule the liver makes more cholesterol than it needs whereas there are parts of the body that need more cholesterol than they are typically capable of making especially during periods of

high stress so those parts of the body need to shuttle cholesterol need to receive cholesterol and this poses a little bit of a problem because the main channel that we like to use in the body to transport things back and forth is of course the circulatory system it is not the only system we have a lymphatic system but the circulatory system is the system that we tend to use uh most to transport things like this now there are lots of things we transport in the circulatory system and we do without any difficulty right we transport

glucose without any difficulty we transport electrolytes without any difficulty we transport lactate without any difficulty why because all of those things that i just stated are water soluble and of course the circulatory system is made up of plasma and proteins that's what your blood is the plasma being basically the water of the cell and so things that are water soluble like all of the proteins hemoglobin and things like that things that i already stated glucose electrolytes they are soluble in water and therefore they transport easily but as i said at the very outset cholesterol is

a lipid and if you remember a little bit from a chemistry class you'll know that a lipid is not water soluble it is hydrophobic as opposed to what we say is hydrophilic so things that are hydrophobic can't move in water just as you would dump olive oil into a glass of water you would quickly realize how much they repel each other so we have this totally essential thing that we have to move around the circulatory system otherwise we would die and we can't do it directly because the medium through which we need to transport it

repels the thing we're trying to transport aha there's a solution we need to create a vehicle that we can transport this in and that vehicle is called a lipo protein and as its name suggests lipo and protein it's part lipid part protein and it's engineered in a way that the lipid part is on the inside the protein part is on the outside protein is water soluble so now you create this spherical molecule which on the inside you can package the cargo that is hydrophobic repels water and on the outside you have a coating that is

hydrophilic that is attracted to water and moves effortlessly through the water and that's how we transport cholesterol now broadly speaking these lipoproteins traffic in two types of families a family that is defined by apob which is a lipoprotein that wraps around it or an april like the protein that wraps around the spherical larger lipoprotein and apo a there's an apoa family there's an apo b fan technically there is another there's two apob families there's an apob 100 and an apob 48 i'm going to ignore the apob 48 right now that just exists on kyla microns

and we could do another class on that in another day but for now we're going to focus on apob 100 which defines the lineage of lipoproteins that are terms you've probably heard of vldl idl ldl lp little a and the apoa lipoproteins define a totally different class of these called hdls so what do those names mean anyway vldl idl ldl hdl they all refer to another feature of the lipoproteins that is distinct from the apa lipoprotein that wraps around them which is their density so if you think about you know like a high school experiment

where you take various different substances and you put them into water you might notice that you can separate how they would float now water's kind of a bad example of how that works because things are typically binary behaving in water either they're sync or they're going to float but i think that gives you a conceptual understanding of the difference in density so density is mass over volume and a higher density object relative to a lower density object will sink versus float so if you take all of those lipoproteins that i mentioned all of the apob

ones all of the apoa ones and you put them in a certain type of gel in the lab you can see a separation of them based on their density and the highest density ones of those we just call the high density lipoproteins the hdls you have more than one apoa on an hdl and you have different subclasses of hdls hdls are really complicated and we don't even come close to understanding all the ins and outs of them which by the way is why i get really annoyed when people say having a high good cholesterol is

good and what again what they really mean to be saying is having a high hdl cholesterol is good and while it's true that on average higher hdl cholesterol is associated with and traffics with metabolic health in a way that low hdl cholesterol tends to traffic with bad metabolic health you can absolutely not tell by looking at an individual based on how high their hdl cholesterol is if they're in good shape or not because that single snapshot of how much cholesterol is in the hdl tells you nothing about the functionality of the hdl and it's the

functionality of the hdl that matters i'm not going to talk anymore about that because i have an entire podcast coming out on hdl biology at some point in the next few months where we'll go into that in great detail but it should be reminded uh it should be stated that efforts to raise hdl cholesterol pharmacologically have by and large mostly not exclusively but mostly failed in uh improving outcomes okay so over on the ldl apob side the most abundant apo b100 or apob for short lipoprotein is the low density lipoprotein that's the one that gets

called bad cholesterol and again on the apo a side we have hdl which gets called good cholesterol so a couple things i want to say on this one if you're talking ldl you are referring to the low density lipoprotein if you say hdl you are referring to the high density lipoprotein but if someone says what is your hdl what is your ldl they're asking for a laboratory metric they are asking incorrectly there is no laboratory metric called ldl or hdl there is hdl cholesterol ldl cholesterol abbreviated ldl c and hdlc there's ldlp and hdlp which

is the particle number of ldl which can be counted via electrophoresis or nmr of course my preferred way to count the number of these particles is to look at b the apob concentration to me is the most important number you want to understand to predict from a biomarker standpoint your cardiometabolic risk or a cvd risk because it captures all of the atherogenic particles so apob counts the total of the ldls inclusive of the lp little a's the ideals although they virtually never exist they have such a short resonance time and the vldls which can become

problematic in people with metabolic syndrome and high triglycerides so apob gives you the total atherogenic burden of those lipoproteins and therefore i think it's the preferred metric by which we want to assess risk but if you want to look at ldl you have to look at ldl c ldl cholesterol and hdl you look at hdl cholesterol now is the cholesterol in the hdl any different from the cholesterol in the ldl no of course not therefore it is totally erroneous to say hdl is good cholesterol and ldl is bad cholesterol no instead what is true is

that ldls themselves as lipoproteins are bad actors because of what they do what they do is they go into artery walls where they get oxidized and they basically dump their oxidized sterile contents into the sub endothelial space which elicits an immune response and a whole bunch of other things that lead to atherosclerosis which i'm not going to get into now but the point of this discussion is that i want people to understand that ldls and hdls are lipoproteins if you want to talk about the cholesterol you talk about ldl cholesterol and hdl cholesterol but the

cholesterol in them is the exact same and there is no such thing as good cholesterol or bad cholesterol and so you just have to be careful when you see things written that are written through that lens because what it tells you is the person writing this doesn't understand the basics of lipids and lipoproteins and if they don't understand the basics of lipids and lipoproteins because what i just told you guys is literally the 101 on this subject right that we didn't get to the senior level class let alone the graduate level class and this is

complicated stuff once you get into that level so if someone writing to me is butchering the 101 you can stop reading because whatever else they're saying they're undoubtedly screwing it up okay so there it is there's the tldr on lipids