Five Essential Functions of Cholesterol: Why It's Vital for Human Health

Have you heard that cholesterol isn’t the villain it has been made out to be?

While elevated LDL blood cholesterol is often blamed for causing heart disease, this broad generalization is increasingly being questioned. Emerging evidence suggests that high LDL cholesterol alone may not raise heart disease risk in metabolically healthy people, including those who eat ketogenic or low-carb diets.(1, 2) However, not all experts in the field of cardiometabolic health agree on this, and research is ongoing.

What can’t be disputed is that cholesterol plays several essential roles in the body. (Note: This is different than saying cholesterol is an “essential” nutrient, meaning one that your body can’t make on its own. In fact, cholesterol is so important that your body can produce it, primarily in the liver.)

Let’s briefly explore five of these critical functions:

1. Building and Maintaining Cell Membranes 

Every cell in your body is surrounded by a membrane, which acts like a protective barrier, controlling what goes in and out of the cell. Cholesterol is an important component of cell membranes. It ensures that they are strong enough to protect cells yet flexible enough to allow small molecules, including nutrients, to move in and out.(3) It also plays a role in regulating membrane protein function.(4) Without adequate cholesterol, cell membranes would be too fluid and unstable, compromising the integrity of cells throughout the body.

2. Hormone Production 

Cholesterol is a building block for several steroid hormones, including cortisol, aldosterone, estrogen, progesterone, and testosterone.(5) Each of these hormones plays a unique role in maintaining your body’s health and balance. They help regulate metabolism, stress response, fluid balance, and reproductive health. Without cholesterol, your body wouldn’t be able to produce these critical hormones.

3. Bile Acid Synthesis 

Your liver uses cholesterol to make bile acids, which break down fats in the food you eat and allow your body to absorb important nutrients like fatty acids and the fat-soluble vitamins A, D, E, and K. In addition, bile acids play a protective role in the intestines by helping to prevent inflammation and infection. They do this by promoting the integrity of the intestinal lining, which is crucial for preventing harmful substances from entering the bloodstream.(6)

4. Vitamin D Production 

When your skin is exposed to UV rays from the sun, cholesterol is converted into vitamin D3, a fat-soluble vitamin. In the liver, vitamin D3 is converted to 25-hydroxyvitamin D, which the kidney then processes into its active form, 1,25-dihydroxyvitamin D. This active form of vitamin D supports bone health, immune function, and mood regulation.(7) Ensuring adequate production of vitamin D is important, since vitamin D deficiency has been linked to a range of health issues, including fractures, bone loss, and infection.(8)

5. Supporting the Brain and Central Nervous System  

About 20% of your body’s cholesterol is in the brain, where it helps build and maintain connections between nerve cells needed for all physiological functions, including learning and memory.(9) Indeed, brain cholesterol imbalances are associated with cognitive decline and neurological disorders.(10) For this reason, cholesterol is crucial for staying mentally sharp. In addition, cholesterol is an important part of the myelin sheath, which encases nerves and protects them.(11) The myelin sheath also ensures that nerve signals are transmitted rapidly and smoothly, allowing for quick, precise responses throughout the body.

Debates about LDL cholesterol’s role in heart disease are likely to continue. But by understanding its vital functions, we can appreciate the importance of cholesterol and take a more balanced approach to managing our health.

To learn more about cholesterol, other lipids, and the potential positive effects a ketogenic diet may have on your lipoprotein profile, read The Keto Diet & Cholesterol: Digesting the Facts.

REFERENCES

1. Statin therapy is not warranted for a person with high LDL-cholesterol on a low-carbohydrate diet, Current Opinion in Endocrinology, Diabetes and Obesity 2022
2. Elevated LDL Cholesterol with a Carbohydrate-Restricted Diet: Evidence for a “Lean Mass Hyper-Responder” Phenotype, Current Developments in Nutrition 2021
3. Nonuniversal impact of cholesterol on membranes mobility, curvature sensing and elasticity, Nature Communications 2023
4. The influence of cholesterol on membrane protein structure, function, and dynamics studied by molecular dynamics simulations, Biochimica et Biophysica Acta Membranes 2015
5. Cellular cholesterol delivery, intracellular processing and utilization for biosynthesis of steroid hormones, Nutrition and Metabolism 2010
6. Functional, Diagnostic and Therapeutic Aspects of Bile, Clinical and Experimental Gastroenterology 2022
7. Vitamin D, an essential nutrient with versatile functions in nearly all organs International Nutrition Research 2013
8. Vitamin D deficiency 2.0: an update on the current status worldwide, European Journal of Clinical Nutrition 2020
9. Cholesterol metabolism and homeostasis in the brain, Protein & Cell 2015
10. Brain cholesterol homeostasis and its association with neurodegenerative diseases, Neurochemistry International 2023
11. Local cholesterol metabolism orchestrates demyelination, Trends in Neurosciences 2022