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Thankfully, the idea that cholesterol, whether in your food or in your body, is a one-way ticket to disease and death, is starting to die.  The infamous 1984 TIME magazine cover of a frowny face made out of bacon and eggs met its match in 2014, when a doctor said it was okay to eat butter again. (See these iconic images here.)  Indeed, rather than existing solely to “clog your arteries,” cholesterol is increasingly being shown to be protective for various aspects of physical and mental health.

Did you know that your own body makes cholesterol?  That’s right.  Your body synthesizes cholesterol—far more of it than you get from your diet, even if you eat loads of butter and egg yolks.  It’s unlikely your body would produce so much cholesterol if this substance existed only to cause trouble.  To the contrary, it looks more and more like cholesterol has beneficial effects we’re only beginning to uncover.

Here’s the short list of critical things cholesterol does:

  • Essential structural component of the myelin sheath, which insulates and protects neurons and facilitates communication between them
  • Essential structural component for cell membranes
  • Required for synthesis of all steroid hormones, including testosterone, estrogen, progesterone, cortisol, and more
  • Serves as a raw material for endogenous (internal) production of vitamin D, via the interaction of sunlight with your skin
  • Required for proper function of serotonin receptors in the brain
  • Essential component of bile salts, which are required for the digestion of fats and fat-soluble vitamins
  • Repair substance, needed for repair and regeneration of damaged tissue

Let’s take a closer look at the first thing in that list: cholesterol is a building block for myelin, which is essential for healthy nerve cell structure and function.  The neurodegenerative disorder multiple sclerosis (MS) is multifactorial, but one of the main issues is a loss of myelin in neurons in the brain.  This loss of myelin impairs proper neuron function, which results in muscle weakness, lack of coordination, fatigue, and more.

Cholesterol Beneficial for Multiple Sclerosis

A study in the prestigious journal Nature found dietary cholesterol to be highly beneficial in a mouse model of multiple sclerosis.  The authors wrote, “Supplemented cholesterol can directly support myelination by incorporation into myelin membranes.  […]  The current study suggests that cholesterol provides a ‘fast track’ to remyelination and repair.”  In case you’d prefer a basic translation, they’re saying that cholesterol in the diet can facilitate replacement of lost myelin.

The same authors had shown in previous animal models that “cholesterol is rate limiting for CNS myelination.”  When something is “rate-limiting” in terms of human physiology, it means it’s the key factor.  In the case of cholesterol and remyelination, all the other required things can be in place, but if there’s not enough cholesterol, myelination won’t happen, or it won’t happen as quickly and effectively as it should.  As stated earlier, your body produces cholesterol on its own, but in some individuals, internal synthesis may be inadequate to keep up with the body’s demand for it.  For these people, cholesterol might be considered “conditionally essential,” and they might need to get more of it from their diet.  (Not exactly a hardship, considering they can choose from shrimp, cheese, butter, bacon, ribeye steak, eggs, and other cholesterol-rich foods.)

The authors of the study note that patients with MS have disturbed brain lipid metabolism, but that blood cholesterol levels are usually in the normal range.  During active disease and disease progression, however, total cholesterol often rises to the upper limit of the normal range.  It’s not known whether this is a cause or consequence—being that cholesterol is so critical for myelin synthesis, ramping up cholesterol production may be the body’s way of trying to provide more of this essential substance.  For those whose endogenous synthesis is inadequate, increasing dietary cholesterol may be helpful.  Researchers showed that mice fed a diet enriched with extra cholesterol had better remyelination compared to mice not supplemented with high-cholesterol chow.

According to the researchers:

“Dietary cholesterol supplementation supports cholesterol metabolism in the CNS [central nervous system] and has the remarkable potential to ameliorate disease by facilitating several repair mechanisms, leading to improved remyelination and neurological outcome.”

Beyond MS: Cholesterol Helpful for ALS and Mental Health

Multiple sclerosis isn’t the only condition where increased cholesterol could be of benefit.  It’s been observed that higher cholesterol—including LDL—is associated with increased lifespan in amyotrophic lateral sclerosis (ALS, a.k.a. Lou Gherig’s disease).  The title of one study says it all: Dyslipidemia is a protective factor in amyotrophic lateral sclerosis.  (“Dyslipidemia” typically refers to high cholesterol, especially high LDL, and sometimes high triglycerides.)  Perhaps it’s time to stop calling it dyslipidemia, as the “dys” implies something dysregulated, abnormal, or harmful.  In the case of ALS, and possibly other neurodegenerative disorders, elevated cholesterol may be beneficial.

In ALS patients, “an abnormally elevated LDL/HDL ratio significantly increased survival by more than 12 months.”  Maybe it’s not really abnormal, then, but the body actually trying to protect and sustain itself.  It only seems “abnormal” when we operate under the premise that LDL is unquestionably harmful and should always be kept low.

The ultimate cause of death for most patients with ALS is respiratory failure, which progresses slowly over months, as nerve damage impairs communication with the diaphragm.  Some evidence indicates that respiratory impairment is associated with a decrease in cholesterol and a lower LDL/HDL ratio.

Low cholesterol is also associated with violent behavior and substantially increased risk for suicide.  In a cohort of Canadian subjects, individuals with the lowest total cholesterol had more than six times the risk of committing suicide compared to subjects with the highest cholesterol.  By itself, this doesn’t mean that low cholesterol causes people to attempt suicide, but the association between low cholesterol and increased risk for violence and suicide has been found numerous times, and it bears more detailed investigation, especially when you consider that cholesterol is essential for hormone production, cognitive function, healthy moods, and just about anything else you can think of that affects physical and mental health.

It’s long past time to rethink cholesterol.  It may not be desirable to have total cholesterol or LDL through the roof, but increasing evidence suggests low cholesterol may be far more problematic than high cholesterol.

Sources

  1. Berghoff SA, Gerndt N, Winchenbach J, et al. Dietary cholesterol promotes repair of demyelinated lesions in the adult brain. Nature Communications. 2017;8:14241.
  2.  Dupuis L, Corcia P, Fergani A et al. Dyslipidemia is a protective factor in amyotrophic lateral sclerosis. Neurology. 2008 Mar 25;70(13):1004-9.
  3. Chiò A, Calvo A, Ilardi A et al. Lower serum lipid levels are related to respiratory impairment in patients with ALS.
  4. Golomb BA. Cholesterol and Violence: Is There a Connection?. Ann Intern Med. 1998;128:478–487.
  5. Ellison LF, Morrison HI. Low serum cholesterol concentration and risk of suicide. Epidemiology. 2001 Mar;12(2):168-72.