As I was scrolling through the Ancestral Health Society youtube channel (have you been? You need to!) I came across Peter Attia’s Straight Dope on Cholesterol presentation from AHS12. That would have been a great one to see in person, as he explains succinctly his understanding of cholesterol in light of the current view on its importance in health outcomes. Over the last year or so this controversial topic has hit the media (including the Catalyst documentary investigating the use of statin medication for lowering cholesterol – a report on the resulting controversy can be found here), resulting in more people being confused about their own cholesterol readings. There is no dispute that your blood cholesterol increases with an increasing intake of fat; the real question is whether this might, over the long term, affect overall health outcomes. When looking more closely at the literature it would seem that, for the most part, messages around cholesterol and heart disease risk have largely been inflated over the years – driven by a misinterpretation or a misrepresentation of the available data. Indeed, when you look at the relationship between cholesterol levels and heart disease, around half of those who have heart related incidents have low blood cholesterol (see this summary from Chris Kresser). Does this mean that a low cholesterol level is as problematic for heart conditions as a high cholesterol level? That’s the wrong question to ask I think. The more important question is around context. It’s potentially quite different for someone with high cholesterol who has all of their health risk factors dialled in (are active, eat a minimally processed diet, manage their stress appropriately, have achieved work/life balance… I know what you’re thinking: who is this mythical creature??) However if someone is inactive, eats a poor diet, is highly stressed and doesn’t sleep, then potentially the amount of cholesterol in the bloodstream could become a main player.
Hmm. Complex, huh? Peter Attia explains cholesterol far better than I have heard anyone else do it – so I thought I’d shamelessly borrow from him (with full disclosure) to provide a synopsis of his explanation in a couple of blog posts.
Firstly – atherosclerosis – what even is it? Atherosclerosis is the thickening of an artery wall leading the the heart due to the build-up of plaque. This narrowing of the artery wall increases the risk of a heart attack. What causes atherosclerosis? Many things – cholesterol, the metabolic syndrome (cluster of risk factors), smoking, triglycerides… these are all related, however, atherosclerosis is the presence of a sterol in an arterial wall macrophage. Everything else aside – if you do not have this, then you do not have atherosclerosis. A sterol is not just that which is found in animal based sources (cholesterol) but also in plant based sources (phytosterols). These are different in structure but both have the potential to be involved in the development of atherosclerosis (see the picture below).
When people talk about cholesterol they often refer to them as ‘good’ or ‘bad’ – like us kiwi’s pronouncing ‘Nestles’ as it is written, it’s all in how it’s been sold to us over the years. Cholesterol is essential. Without cholesterol we can suffer major health problems – the causes of which include genetic, however more interesting from a population standpoint to my mind is the link between low cholesterol and depression. Anyway). It’s involved in many processes in the body – while I won’t detail them all here, of note is its role in hormone production. Cholesterol is a precursor for sex hormones testosterone and oestrogen, also for cortisol and aldosterone. Another role is in the creation of a bilayer within virtually every cell, and holds proteins within them. Without this, we wouldn’t have the necessary fluidity that allows cells to move or interact with each other.
Cholesterol comes from both the food we eat and what our body produces – the difference is in the amounts. We consume approximately 300-500mg/d – and in New Zealand there is no longer a recommended maximum limit. Endogenously, we produce around three times that much – around 800-1200mg/d. The liver is largely responsible for this and if it gets messages that there is not enough cholesterol available, it will product more. Virtually all cells in the body are responsible for producing enough cholesterol to be sufficient for life, other than the adrenal cortex and the gonad two important exceptions given the importance of cholesterol for the function of these (the hormones I mentioned earlier).
Along with the production of cholesterol, the liver collects it there also. It is deposited into bile salts (which couldn’t be produced without cholesterol) and gets delivered through the biliary system into the gastrointestinal system. Our gut regulates how much cholesterol gets reabsorbed in the body, and most of this cholesterol is either that which is recycled or produced by the body – the rest comes from our diet. Overall, we have 40-50 grams of cholesterol in our body – so the 300-1200mg is really a drop in the ocean compared to actual cholesterol content in the body. Thus, it is a highly regulated process. While many people believe these small amounts trickling in and out of the system have influenced the action of cholesterol (and subsequently its importance in terms of overall health risk) Peter argues that it’s much more likely that any ‘abnormal’ reaction to cholesterol is in fact regulated by the internal system.