Cholesterol
The most misunderstood molecule in nutrition. Cholesterol is essential for life - every cell membrane needs it, your brain is rich in it, and it's the precursor to all steroid hormones, bile acids, and vitamin D. Your body makes 80% of its cholesterol; dietary intake has minimal impact on blood levels for most people.
Why Cholesterol Is Essential
Cell Membranes
Every cell membrane contains cholesterol, which regulates fluidity and permeability. Essential for cell function.
Steroid Hormones
Pregnenolone (the mother hormone) is made from cholesterol. All sex hormones and cortisol derive from it.
Vitamin D
7-dehydrocholesterol in skin converts to vitamin D3 when exposed to UVB sunlight.
Bile Acid Production
Liver converts cholesterol to bile acids for fat digestion. Primary way body excretes excess cholesterol.
Brain Function
25% of body's cholesterol is in the brain. Essential for synapse formation, learning, and memory.
Myelin Sheaths
Cholesterol is a major component of myelin, the insulation around nerve fibers that speeds signaling.
Understanding LDL and HDL
LDL and HDL are not cholesterol - they're lipoproteins that carry cholesterol through the bloodstream.
LDL (Low-Density Lipoprotein)
- Delivers cholesterol to cells
- Called "bad" because it can deposit in arteries
- LDL particle count (LDL-P) may be more important than LDL-C
- Small, dense LDL particles are more problematic
- Oxidized LDL is the real concern
HDL (High-Density Lipoprotein)
- Returns cholesterol to liver
- Called "good" because of reverse transport
- Also has antioxidant and anti-inflammatory properties
- HDL functionality matters more than just levels
- Exercise and moderate alcohol increase HDL
Diet and Blood Cholesterol
The relationship between dietary cholesterol and blood cholesterol is complex and often misunderstood:
Dietary Cholesterol
For most people, eating cholesterol has minimal effect on blood levels. The body compensates by making less. Eggs are no longer restricted.
Saturated Fat
Can raise LDL in some people, but often raises HDL too. Context matters - with what carbs? Whole foods vs processed?
Refined Carbs/Sugar
Often worse for lipid profiles than dietary fat. Raises triglycerides, creates small dense LDL, lowers HDL.
Individual Variation
Some "hyper-responders" do see LDL rise with saturated fat. Genetics (APOE, etc.) influence response significantly.
Statins and the Mevalonate Pathway
Statins block HMG-CoA reductase, reducing cholesterol synthesis. But they also reduce other products of the mevalonate pathway:
CoQ10 Depletion
CoQ10 uses the same pathway. Statins can deplete it, potentially explaining muscle side effects.
Vitamin K2
Mevalonate pathway also produces MK-4 (vitamin K2). May affect arterial calcification.
Dolichols
Needed for glycoprotein synthesis. Depletion may affect cell signaling and nerve function.
Better Cardiovascular Markers
Total cholesterol alone is a poor predictor of cardiovascular risk. Consider these more informative markers:
Triglyceride/HDL Ratio
Under 2 is ideal, under 3 is good. Better predictor than LDL for many outcomes.
LDL Particle Count (LDL-P)
Number of particles may matter more than cholesterol content per particle.
ApoB
Measures all atherogenic particles. Single best predictor according to some researchers.
Lp(a)
Genetic risk factor. High levels increase cardiovascular risk regardless of other lipids.
Key Connections
Bile Acids
Cholesterol is converted to bile acids for fat digestion
Vitamin D
Cholesterol in skin converts to vitamin D with sunlight
Cortisol
Made from cholesterol via pregnenolone
Testosterone
Steroid hormone made from cholesterol
Estrogen
Steroid hormone synthesized from cholesterol
CoQ10
Shares the mevalonate pathway with cholesterol