Overview
Cholesterol is possibly our single most important all-purpose protective molecule. In the 1920s, researchers injected animals with heavy metals, snake venom, infectious bacteria, and other potent toxins. They then gave them a cholesterol injection and found it antidoted essentially all of them. It is the raw material the body converts into pregnenolone, progesterone, DHEA and other protective steroids. It's a structural component of every part of the cell, including the chromosomes, the cell division apparatus, the respiratory system, and the microtubules (not just the cell membrane as textbooks claim). Artificially suppressing cholesterol with statins lowers the protective steroids in exact proportion, which is why statin drugs increase all-cause mortality.
Key Points
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Cholesterol is our basic defensive molecule and functions like a protective hormone in its own right. Since about 1920, injecting pure cholesterol has been shown to protect against otherwise lethal doses of bacterial toxins, mercury, plant toxins, spider and snake poisons. It stabilizes red blood cells, protects against heavy metal poisoning, and improves learning and memory when injected in animal experiments. The testes produce sperm more efficiently in its presence, and it protects cells against heat damage that would otherwise break them down.
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The conversion of cholesterol to the protective steroids depends on thyroid and vitamin A. In experiments where blood flows through an adrenal gland or ovary, the amount of progesterone coming out corresponds directly to the amount of cholesterol going in, provided thyroid and vitamin A are present. This is a massive quantitative conversion; a very large portion of circulating cholesterol is being turned into pregnenolone, progesterone, and DHEA moment to moment. Without adequate thyroid and vitamin A, the cholesterol stays in the blood instead of becoming the hormones that actually do the protective work.
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High blood cholesterol is a mirror image of thyroid function. When the thyroid gland is removed surgically, cholesterol rises sharply within weeks; when thyroid is supplemented, cholesterol returns to normal. Two people with cholesterol of 400 and 500+ were brought down to the normal range of around 200 within a week using physiological doses of T3 at roughly five micrograms per hour. You do not get a high excess cholesterol in the blood without being hypothyroid, which means the cholesterol itself is not the problem; the thyroid deficiency behind it is.
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Cholesterol is everywhere in the cell, not just in membranes. It is stuck to the chromosomes, to the structural microtubules and microfilaments, to the respiratory apparatus, and to the cell division machinery. The claim that 97% of cellular cholesterol is in the cytoplasmic membrane ignores the 97% of its real functions, which are to control the entire physiology of the cell. Its lubricating, limbering effect on these complex polymer mixtures is what lets proteins, starches, nucleic acids, and water coexist in the organized coacervate state of living tissue, going back to Bungenberg de Jong's work on emulsions nearly a century ago.
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The cholesterol found in arterial plaque is a repair response to polyunsaturated fat damage, not a cause of heart disease. The 1912 rabbit experiments that launched the cholesterol theory used cholesterol dissolved in vegetable oil; the vegetable oil was the actual culprit. When the same cholesterol is given with adequate thyroid hormone, it does not damage circulation. When PUFA is removed from the diet of lab animals, the circulatory pathology from cholesterol disappears. Cholesterol is there in the arterial wall primarily to protect the cells against the free radicals produced by polyunsaturated fats.
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Cholesterol below 200 over age 50 is associated with dementia, violence, and higher all-cause mortality. The Framingham study showed that people over 50 with cholesterol below 200 were more likely to develop Alzheimer's. A large study of violent offenders divided populations at 180 cholesterol and the violent group was clearly on the below-180 side. A nursing home study that followed women from admission to death found the longest-lived and most mentally sound had cholesterol around 270. The idea that everyone should be under 200 is a pharmaceutical sales target, not a health target.
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Statins cause muscle breakdown, brain damage, depression, and suicide because they interfere with the whole cholesterol synthesis pathway. Blocking HMG-CoA reductase also blocks the synthesis of coenzyme Q10 and several other essential molecules. Statins cross the blood-brain barrier, which means the same process that dissolves muscle tissue during exertion, rhabdomyolysis, can happen in the brain, accounting for the depression, suicidality, and memory loss people experience. Bones rot, muscles dissolve, and emotional stability collapses when cholesterol is chemically suppressed.
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Arterial plaques are made of peroxidised PUFA aldehydes. Recent research has confirmed that roughly 80% of the atherosclerotic plaque lining arterial walls is composed of aldehyde byproducts of linoleic acid peroxidation. The rest is calcium, dead white blood cells, and a small amount of cholesterol present in a reparative role. The original cholesterol theory of heart disease was never causatively proven, and even the most committed proponents acknowledge this. Only oxidised cholesterol appears in the lesions, and oxidation is driven by reactive oxygen species that PUFA generates.
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LDL is the actual useful cholesterol; HDL is often a marker of toxicity. Things that reliably elevate HDL are things that damage the body: ethanol, ionising radiation, excessive exercise, estrogen, and birth control pills. Women on birth control often present with "perfect" HDL above 60 while being in a severely toxic hormonal state. HDL's main physiological role is to carry endotoxin from the bloodstream back to the liver for neutralisation, so elevated HDL in the absence of an obvious toxic exposure often indicates gut endotoxemia. Every pharmaceutical drug designed to raise HDL has failed in clinical trials, and several actually increased hemorrhagic stroke risk.
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Cholesterol has direct antiviral and antimicrobial activity. It can neutralise pathogens that enter the bloodstream, functioning as a backup defense when white blood cell counts are low or compromised. Lowering cholesterol in immunocompromised or chronically ill people deprives them of one of their remaining protective mechanisms. This is why statin-treated patients often show increased susceptibility to infections, and why viral illnesses track inversely with cholesterol levels over time.
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Fructose and sugar support cholesterol synthesis. Fructose is a highly efficient substrate for hepatic cholesterol production. On a carbohydrate-rich diet, cholesterol rises because synthesis is being supplied properly. This is one of several reasons a pro-metabolic diet produces higher cholesterol numbers than a low-fat or low-carb diet, and these higher numbers are a sign of good metabolic function rather than a risk factor.
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The FDA quietly reversed its dietary cholesterol position in 2019. After fifty years of recommending restricted dietary cholesterol, the FDA announced that dietary cholesterol has no impact on cardiovascular disease risk. The studies they cited actually went further than the announcement, showing inverse correlations in several cases (more dietary cholesterol associated with lower cardiovascular risk). The FDA did not extend this reversal to serum cholesterol or statin recommendations, which would have been devastating commercially, but the underlying evidence is even broader than the official reversal suggests.
Notable Quotes
"I've known several doctors and such who deliberately kept their cholesterol down and bragged about having 100 or 120 milligram cholesterol, and I don't think any of them lived much beyond 40 years."
[Ray Peat — Heart 2]
"Next to glucose, it's probably our single most important protective all-purpose molecule."
[Ray Peat — Sugar 2]
"The cholesterol is there primarily to protect the cells against the free radicals produced by the polyunsaturated fats."
[Ray Peat — Cholesterol Is An Important Molecule]
"You don't get a high excess cholesterol in the blood without being hypothyroid."
[Ray Peat — Thyroid and Regeneration]
"Lowering cholesterol by any drug means has pretty serious side effects."
[Ray Peat — Sugar 2]
"Things that raise HDL are invariably toxic."
[Georgi Dinkov — A Bioenergetic View of Heart Disease and Stroke [Generative Energy #22] (Danny Roddy)]
"Cholesterol is just an innocent bystander. It's like blaming firefighters for the fire."
[Georgi Dinkov — Dr. Mercola interview with Georgi Dinkov]
"Cholesterol protects against viral infections. It can neutralize some pathogens that enter the system."
[Georgi Dinkov — Rooted in Resilience interview with Georgi Dinkov]
"Low cholesterol is predictive of developing cancer two decades before any sign."
[Georgi Dinkov — Rethinking Cancer Through Cellular Energy & Metabolism with Georgi Dinkov (Strong.Sistas)]
Important Things To Consider
High cholesterol is a thyroid problem, not a cholesterol problem. Trying to lower cholesterol while ignoring the hypothyroidism behind it is backwards. Thyroid supplementation with T3 at physiological doses can bring very high cholesterol down to normal within a week, because the body starts converting it into progesterone, DHEA, and pregnenolone as it should have been doing all along. The cholesterol level is diagnostic of metabolic function; suppressing it chemically while the thyroid stays low removes the body's emergency adaptation without fixing the underlying failure.
Minimum cholesterol should not drop below roughly 160. Below that threshold the associations with violence, depression, cancer, and dementia start to appear consistently in the literature. The Hungarian study from the mid-1980s chemically lowered cholesterol and saw mortality rise from every cause, including cancer, suicide, accidents, and homicide. If cholesterol is below 160, the question is why, and the answer is usually either PUFA overload, carbohydrate deficiency, or active suppression by a drug.
Cortisol rises to fill in when cholesterol cannot be converted to the protective steroids. When thyroid is low and the conversion pathway fails, the body defaults to cortisol production, which handles stress by breaking down thymus, muscle, skin, and liver tissue to generate glucose. The chronic cortisol elevation associated with high cholesterol and low thyroid is what actually damages blood vessels, promotes osteoporosis, and drives the tissue atrophy blamed on cholesterol itself.
Cholesterol synthesis in the skin, adrenals, intestine, and liver drops by about 50 percent with age. This is why older skin needs roughly twice as much sunlight to produce the same vitamin D as young skin. The adrenal glands, which produce not only steroid hormones but also large amounts of cholesterol, show the same age-related decline. Supplementing the diet with adequate cholesterol-containing foods like eggs, dairy, and liver becomes more important with age, not less.
Chasing a low LDL number is counterproductive. The LDL above which cardiovascular risk genuinely rises is much higher than the thresholds clinical guidelines suggest, and the evidence for treating LDL under 190 mg/dL is weak to nonexistent. Meanwhile the risks of driving LDL artificially low include cancer, infection, and neurodegenerative disease. A healthy cholesterol on a pro-metabolic diet with plenty of sugar and saturated fat will commonly sit between 180 and 240 mg/dL, and this is not pathological.
HDL above 60 is usually a warning sign. When someone presents with HDL in the 60s or 70s without an obvious cause, look for alcohol consumption, estrogenic exposure (birth control, HRT, endocrine disruptors in plastic or cosmetics), excessive exercise, or gut endotoxemia. HDL elevation in this range is a response to toxicity, not an indicator of cardiovascular protection. The pharmaceutical industry has repeatedlt failed to produce a drug that both raises HDL and lowers cardiovascular events.
Measuring oxidised LDL is more informative than total LDL. Since only oxidised cholesterol appears in atherosclerotic lesions, and the oxidation is driven by PUFA and reactive oxygen species, oxidised LDL is a better predictor of actual cardiovascular risk than total LDL. Not all clinical labs offer this test routinely but it is worth requesting if available.
Saturated fats raise cholesterol. If someone transitions from a PUFA-heavy diet to a Peat-style saturated-fat-rich diet, LDL will often rise meaningfully. This reflects the cell's reduced need to pull cholesterol from circulation to repair PUFA-damaged membranes, not a pathological process. In this context, the rise in LDL is metabolic restoration, not deterioration.
PUFA restriction is the single most important dietary intervention for cardiovascular health. Since peroxidised linoleic acid aldehydes constitute the bulk of atherosclerotic plaque, reducing dietary PUFA below roughly 4% of calories provides more cardiovascular protection than any cholesterol-targeted intervention. This means removing seed oils (corn, soy, canola, sunflower, safflower), most fried foods, and most processed foods, while increasing ruminant fat, butter, ghee, coconut oil, and tropical fats.