Most people assume that cholesterol is a harmful substance, as they’ve been taught that for the past 70+ years. All they know is that cholesterol is “bad” and that it “causes” heart disease.
While cholesterol does play a part in vascular disease, it is absolutely essential for life.
It’s obvious, then, that cholesterol has important roles in the body. The human body produces approximately 1,200 mg of cholesterol daily. It wouldn’t make any sense for our bodies to synthesize something that is harmful.
Cholesterol is transported throughout the body. In fact, there are specific receptors for LDL cholesterol that have been identified in the adrenal glands, gonads, muscle, and adipose tissue (ref).
Here are some of the many critical functions in which cholesterol plays a role.
Functions of cholesterol
– Cholesterol comprises the cell membrane of every cell in the human body. As a critical component of the phospholipid bilayer membrane, it contributes to the fluidity of the cell (ref).
– 25% of our body’s total cholesterol is in the brain. Cholesterol is an indispensable component of the myelin sheath, which insulates the neurons and is critical for rapid nerve conduction. Inadequate cholesterol impairs neurologic function. Cholesterol is also critical for signaling at the synapses with neurotransmitters. Since cholesterol cannot enter the brain, it is made by glial cells within the brain – a process that is inhibited by statins.
– Synthesis of steroid hormones (e.g., cortisol, aldosterone, and adrenal androgens)
– Synthesis of sex hormones (e.g., testosterone, estrogens, and progesterone)
– Synthesis of bile acids, which facilitates absorption of fat and fat-soluble vitamins. Bile acid is the means by which the body can eliminate cholesterol from the body, via the gut. (Note that the breakdown of bile acids is responsible for the brown color of stool.)
– Precursor for the synthesis of Vitamin D
– Contributes to the immune system, preventing bacterial, viral, and parasitic infections (ref). Cholesterol binds endotoxin produced by bacteria, as well as binding the alpha toxins produced by Staph aureus (ref, ref). Studies of mice and rats demonstrate that high levels of LDL cholesterol are protective against mortality from infection compared to low levels of LDL cholesterol. Similarly, individuals with Smith-Lemli-Opitz Syndrome (SLOS), lacking an enzyme necessary for cholesterol synthesis, are typically subject to severe infections. But, when given supplemental cholesterol to increase their LDL cholesterol levels, they have fewer and less severe infections (ref).
– Nutrient transport
– Cellular repair
– Cell signaling
– Transport processes
– Energy delivery
– Regulation of gene transcription
Summary
It’s important to understand that cholesterol is not inherently a harmful substance. It is involved in many critical physiologic processes throughout the body.
Ultimately, it’s what we do to the cholesterol that makes it harmful.
