You are probably aware if you have been reading my blog for a while and following likeminded people that it’s not as black or white as whether or not your high cholesterol level is a problem. Much as I get a bit on edge when I see plates of food without any colourful vegetables (I’m not going to lie to you!), I get a little bit twitchy when I see it professed everywhere that it’s no longer a problem to have a high cholesterol level. Not true. Now cholesterol is essential to life. Without it, we wouldn’t be able to make hormones, repair cell membranes and do 68 other things that require cholesterol. Your body makes 85% of the cholesterol circulating in your bloodstream even, meaning that, for most people, the cholesterol eaten by way of animal products (animal protein, eggs, cream, butter, cheese) will have very little impact on their overall cholesterol level in the body.
One of the main factors that can cause high cholesterol levels is not the cholesterol that you eat (and you’ll be aware that in New Zealand we’ve not had a recommendation around reducing cholesterol containing foods for a while – though the rumour of the egg just will not die). It’s also not just about the fat that you eat. While scientists were busy trying to prove the diet-heart-hypothesis correct over the last 50 years (you know, the one that has pretty much governed our public health nutrition messages and is still today being pushed by nutrition authorities, despite the failure of aforementioned scientists to do so), the powerhouses of the food industry were busy manufacturing and marketing those low fat, processed, refined carbohydrate-based foods that contribute to an inflammatory state which underpins all chronic disease – including heart disease and high cholesterol levels. That is something I have understood well. However after listening to that brainiac Robb Wolf discuss cholesterol with Dr Rhonda Patrick on a recent podcast about cell metabolism the role that the gut plays in both the inflammatory state and our cholesterol levels which could determine whether or not we should be concerned was touched on. One of these was through increasing insulin resistance (IR; and inflammation) at the local level of the gut, and the other was the inflammation that occurs through gastrointestinal or gut issues which may include this IR, but also any challenge which stimulates an immune response.
We know that IR is caused by high circulating blood sugar levels requiring a constant response from our pancreas to produce the hormone insulin to ferret that glucose to where it’s required (working muscle tissue, our carbohydrate stores, red blood cells and retina, brain and excess converted to triglycerides in the liver). Constant and chronic high blood sugar levels and subsequent insulin release causes the pancreas to work overtime which, over time and in some situations, our body is unable to read appropriately or respond effectively – our cells become immune to the insulin trying to deliver glucose and glucose and insulin hang around our blood system causing glycation of proteins, cell damage, oxidation and inflammation. The IR causes systemic inflammation which further drives insulin resistance, higher blood triglycerides, lower HDL cholesterol and weight gain, specifically central weight gain which creates even more inflammation. A bit of a cascade which, if not managed, leads to type 2 diabetes (one of the major ‘end points’ of insulin resistance, if you like). Further, those with type 2 diabetes tend to have higher cholesterol levels. Well, what if this also starts in the gut?
Dr Rhonda Patrick spoke of a paper she read in Nature* that reported on research that showed chronic over consumption of processed refined carbohydrates can cause epithelial cells of the gut to become insulin resistant and unable to take up the sugar. We get IR in the local level of the digestive tract and this is pushed out to the rest of the tissues because of the inherent systemic features of the inflammation. Meanwhile, the bacterial cells that are present in our gut are getting all of the glucose that they want and thriving*. Because the IR means our gut cells aren’t able to take the glucose up, the goblet cells in our gut (the ones responsible for secreting mucus to protect our gut wall) aren’t getting the substrate required for them to make energy and produce the mucus to protect our gut intestinal lining. Over time, with no energy, the gut barrier will begin to break down.
Now – this is where the quality of the carbohydrate matters. Dense carbohydrates such as potatoes, sweet potatoes and minimally processed grains tend not to be metabolised in the upper portion of the small intestine and tend to provide more fermentable substrate that feeds our gut and supports our gut health (for an excellent paper by Dr Ian Spreadbury – incidentally one of the speakers at the upcoming Ancestral Health Society conference in Queenstown in October, click here). This means that these types of carbohydrate are not going to create the inflammation in the way that those refined grains do – the ones that we base our public health recommendations on (cereal, wholegrain bread, pasta and the like).
So, that inflammatory state that is started locally at the gut level is another mechanism that explains how the state of our gut can determine whether your high cholesterol level could be a problem.
The other one more directly affects the LDL cholesterol circulating the body.
FACT: the gut is the nexus to health – it has the largest concentration of immune cells as it is exposed to the external environment (food). Those immune cells are there to fight off things which are pathogenic. The gut also it has the highest concentration of bacterial cells, and immune cells and bacteria together are NOT a good thing, particularly when they come into contact – that’s why we have that epithelial barrier that protects the immune cells. As soon as that barrier breaks down, the immune cells come into contact with the bacteria cells and it’s all on, they start firing off these pro-inflammatory cytokines to kill off the bacteria. This results in the bacteria releasing off endotoxin – which is where some of the problem relating to LDL cholesterol can originate.
Bacteria in the gut have a cell wall called lipopolysaccharide which holds endotoxins –it gets released into the circulation when the bacteria are dying (which is why anyone who is undergoing diet or supplemental changes to change the bacteria in the gut might experience initial discomfort as the bad bacteria die off). This increases production of very low density lipoprotein (and LDL eventually) because these bind endotoxins – they soak it up like a sponge. However, instead of being delivered back to the liver to be recycled it remains in circulation as the endotoxin binds to the LDL receptor on this particle and prevents it from being taken back up by the liver. This will increase the likelihood of the LDL particle being oxidised – a major risk factor for cardiovascular disease. You know it’s not about LDL cholesterol or total cholesterol, it is to do (in part) to particle size –the small dense particles have been associated with heart disease.
Now the problem with these LDL particles that have an endotoxin attached is that they are the smaller, denser LDL particles. These particles, already a risk factor for heart disease now have a bacterial signal floating around the blood stream. This causes your immune cells to suddenly be on high alert. The macrophages that come to kill off the bacteria are attacking the LDL and endotoxin and the subsequent action of the immune system starts a cascade of events which over time will lead to the stiffening and narrowing of the artery as it gets stuck there.
Is your head spinning? Tell me about it. And I’m not a brainiac and suspect this could have been explained far more simply by someone far more intelligent than I. However, the main take home from this is that if you are someone that leads a lifestyle which promotes inflammation (high intake of processed carbohydrates and vegetable oils, little to no vegetable fibre, no exercise, lack of sleep, too much exercise, smoking, high consumption of alcohol…) then your high cholesterol reading could be a problem. That, for most people, should by now be a no-brainer.
However, if you are someone who has these factors dialled in and still has a high cholesterol reading, perhaps it wouldn’t hurt to consider the health of your gut.
*try as I might, I couldn’t find this paper. Let me know if you can as I’m interested to read it. Thanks George.