What has cholesterol ever done for us?

It’s National Cholesterol Month! It was probably created (who does decide these things?) to raise awareness to the ‘dangers’ of cholesterol. Today I’d like to make a plea for cholesterol – probably not what National Cholesterol Month is meant to be about, but here goes …

What comes to mind when you hear the word “cholesterol”? Most likely eggs, bacon, lard, clogged arteries, heart attack, stroke. Something along those lines.

Now for a list of positive associations …



Cholesterol has had a really bad rap over the last 60 years or so, so much so that hardly anyone can think of anything good to say about it. So, is cholesterol a dangerous substance that somehow accumulates in our arteries, only to kill us in the end? What is it? Where does it come from? What does it do?


What is cholesterol?

Cholesterol is a lipid, a waxy substance produced in the liver and all body cells except nerve cells, but there is a special type of brain cells that makes cholesterol, too, because the body’s cholesterol cannot cross the blood-brain barrier. “So, hang on,” you might say “the body makes it? If it’s so bad for us, why?” Exactly. The body does of course produce lots of substances that are bad for us – waste products that occur in normal metabolism and that need to be detoxified -, but cholesterol is not one of them. It has a purpose, several actually, and it is a vital substance.


What does cholesterol do?

Cholesterol is a component of every single cell membrane in the body. It is like a wedge that holds cell membranes together, giving them both stability and the fluidity they need to function. Cholesterol is needed to repair existing cells as well as to make new ones. Any kind of trauma, injury or surgery triggers an increase in cholesterol production, because it is needed for repair.

All steroid hormones, for example cortisol, oestrogen and testosterone as well as neurotransmitters, are made from cholesterol, and so is vitamin D. Steroid hormones regulate energy production, metabolism, hydration, reproduction, behaviour and emotions, the formation of brain, muscle and bone. All rather important … Vitamin D is needed to make healthy bone, protects us from cancer and heart disease, high blood pressure and arthritis.  

The brain makes up 2% of our body weight, but contains 25% of the body’s cholesterol. The substance is part of the myelin sheath, the fatty insulation of nerve cells and allows them to transmit impulses. They would not function without cholesterol.

Cholesterol is a major component of bile, an emulsifier made in the liver that is needed for the proper digestion of fat.

Cholesterol is even involved in immune function. It is found in high concentration in ‘memory cells’ – those cells of our immune system that ‘remember’ a pathogen encountered before. They recognise it and raise the alarm, triggering an immune response.


Can cholesterol be too low?

Smith-Lemli-Opitz Syndrome (SLOS) is a rare genetic condition affecting cholesterol synthesis – children born with this are severely disabled and have a low life expectancy as the brain is underdeveloped. Somewhere between ‘too high’, ‘healthy’ and ‘death’ there has to be a ‘too low’, you would think.

Low cholesterol may contribute to forgetfulness, disorientation, confusion – often seen as normal signs of ageing. The American astronaut and NASA doctor Duane Graveline experienced retrograde amnesia when his cholesterol had been lowered by statin drugs. He was temporarily unable to remember his home address, recognise his wife and children, or remember his job. He stopped taking the drug and his brain function returned to normal. Dr Malcolm Kendrick has written about Dr Graveline on his blog.

Studies have found higher rates of death from unnatural causes (suicide, manslaughter, murder) in people with low cholesterol levels (⩽165 mg/dl or 4.2 mmol/l) (1).  

What’s more: Elevated cholesterol levels appear to be protective in older people. A 2017 systematic review of the literature (3) found that high LDL cholesterol is inversely related to mortality in people over 60 years of age, meaning: the higher your LDL once you’re over 60, the longer you live. This is most likely – as more than a dozen of the reviewed research papers found –because LDL binds to and inactivates a broad range of microorganisms and their toxic products. In other words: Cholesterol protects the elderly from infectious diseases. The full text of this review is available online. Click here to read it.

Considering how vital cholesterol is for life, it stands to reason that it can indeed be too low. Low cholesterol is associated with a number of diseases, but is most commonly caused by statin drugs. It’s not easy to find literature on where the bottom line is, but what little research there is puts it at around 4.0 mmol/l (2, 3). 

So there you have it. Cholesterol is not all bad. In fact it seems to be more good than bad.  

Just in time for National Cholesterol Month, Dr Mark Hyman welcomed British cardiologist Dr Aseem Malhotra on his podcast “The Doctor’s Pharmacy” this week. It’s not all about cholesterol, in fact it is more about bias in research - the two cover a lot of ground - but either way it’s worth having a listen. Click here for the podcast.

If you would like to learn more about cholesterol, here’s a handy reading list of books that take a critical view on the current paradigm.


(1) Psychosomatic Medicine 2000;62 - Epidemiology 2001 Mar;12:168-72 - Annals of Internal Medicine (1998;128(6):478-487), The Journal of the American Medical Association (1997;278:313-321)

(2) Nago et al (2011): Low cholesterol is associated with mortality from stroke, heart disease, and cancer: the Jichi Medical School Cohort Study. Journal of Epidemiology 2011:21(1):67-74.

(3) Ravnskov et al (2017): Lack of an association or an inverse association between low-density-lipoprotein cholesterol and mortality in the elderly: a systematic review. BMJ Open 2016;6:e010401. doi: 10.1136/bmjopen-2015-01040 (Free Full Text)

(4) Hamazaki T, Okuyama H, et al (2015): Towards a Paradigm Shift in Cholesterol Treatment. A re-examination of the Cholesterol Issue in Japan. Ann Nutr Metab 2015:66 Suppl 4:1-116. doi: 10.1159/000381654

(5) Lv YB, Yin ZX et al (2016): Serum Cholesterol Levels within the High Normal Range Are Associated with Better Cognitive Performance among Chinese Elderly. J Nutr Health Aging. 2016 Mar;20(3):280-7. doi: 10.1007/s12603-016-0701-6. (Free Full Text)

(6) Mufti RM, Balon R, Arfken CL (2006): Low cholesterol and violence. Psychiatric Services

(7) Ravnskov, Uffe (2003): High cholesterol may protect against infections and atherosclerosis. Qjm 96.12 (2003): 927-934. 

(8) Ravnskov U, McCully KS, Rosch PF (2011): The statin-low cholesterol-cancer conundrum. QJM (2011): hcr243





What is the appendix for?

One of the most interesting fields of research for me right now is the microbiome. New research in the area comes out every day and the more we learn, the more scientists realise we don’t know.

Although not all bacteria and other microbes have yet been identified – let alone everything they do – we do now know that diversity is key to good health: the more different species there are, the healthier the individual. Hunter-gatherers have a much, much more microbiome than we do in the Western world, and we get many diseases that are unheard of in primitive cultures, e.g. Crohn’s disease.

appendix, appendicitis, microbiome, gut flora, immune system

Appendicitis - infection and inflammation of the appendix - is so common that everyone knows someone who has had it and has had an appendectomy as a result, an operation that probably saved their life.

For as long as we’ve known that this little dead end in our gut exists, doctors and researchers have been wondering what it is for. It was thought to be vestigial, like the coccyx (tailbone) or erector pili (the muscles that make hair stand on end) and body hair. In fact, if you google ‘vestigial organs’ you’ll find the appendix at the top of the list. It is thought not to do anything much, because no purpose has been found and, more than anything, people without one live on without suffering any negative consequences at all.

For other vestigial organs we can find out what there purpose might have been if we look back at our ancestors or closely related species, such as the great apes or monkeys. Our ear muscles, for example, don’t do much anymore, but monkeys use them to twist their ears in different directions, to pick up the sound of approaching danger sooner. Vestigial organs usually have shrunk and/or atrophied: they’re there, but unable to do anything anymore. When it comes to the appendix, however, it appears that apes and humans have a larger and better developed one than monkeys – which suggests that the appendix must be doing something useful.

Most people never get appendicitis, but 6% do, and that’s a lot of people. Of those who do get it, 50% survive it without an operation. Because it’s so common, appendectomy is now routine surgery. So without any medical help, 1 in every 32 people would be wiped out by appendicitis. If it was that dangerous an organ that doesn’t appear to serve any particular purpose, you would expect that over millennia evolution would have made us lose it, not promote it.

It wasn’t until 2005 that it crossed one American scientist’s mind, that perhaps the appendix was a reservoir for bacteria! In order to come up with this idea, there first had to have been knowledge of the gut flora and immunity. The appendix is filled with bacteria, antibodies and lymphatic tissue. Why?

We have more of the same all along the gut, but if we a struck down with infection and disease that causes severe diarrhoea, e. g. cholera, we will lose our gut flora and antibody protection in a very short space of time. Add to that these days enema before colonoscopy or antibiotic treatments. We’ll end up with a very clean gut indeed! But as we now know that is not a very good way to be.

The appendix appears to provide a save haven for bacteria during any such attack, and it is from here that bacteria emerge to recolonise the gut once the threat has passed. So, while we can live without an appendix, there is great benefit in having one. And by the way: appendicitis is another disease that is extremely rare in developing countries. Could the fact that we are so prone to it also have something to do with our Western lifestyle?

For further reading: Rob Dunn - The Wild Life of our Bodies, Harper Perennial, 2011.

Happy Gut - Happy You!

The digestive system is the least talked about and probably our most underrated organ, and yet it truly is the foundation of good health. While I cannot guarantee that a healthy gut will make all your troubles go away, I can safely say that true health will remain out of reach if the digestive system is not working well.


Do you chew your food? Do you think chewing is for whimps? Or those with time on their hands? Don't underestimate the (possibly boring) process of chewing. It's really worth doing. Read on to find out why.