27/06/2026
There is still so much we don’t know about our bodies. This is a great read about cholesterol.
The number on your cholesterol panel measures one thing: how much LDL cholesterol is floating in your blood. It is a concentration, a quantity. What it does not tell you is how those particles behave once they reach the wall of an artery, and that behavior is where the actual trouble starts. Two people can carry the same LDL number and have very different things happening inside the vessel wall, because the particle that drives plaque is not quite the same particle your test is counting.
Cells pull LDL out of circulation through a dedicated LDL receptor, and that receptor has a built-in brake. When a cell has taken in enough cholesterol, it makes fewer receptors and stops absorbing more. This feedback loop, the discovery that won Brown and Goldstein the Nobel Prize, is the reason a cell does not simply gorge itself. Uptake is regulated. The cell takes what it needs and then declines the rest. Native LDL, the untouched particle, moves through this system in an orderly way.
The problem begins when LDL gets chemically modified, most prominently through oxidation. A modified LDL particle is no longer recognized by the regulated LDL receptor. Instead it is picked up by a different set of receptors on immune cells called scavenger receptors, and here is the critical difference: scavenger receptors have no brake. They were described decades ago in a landmark experiment by Goldstein and Brown, who showed that macrophages take up chemically modified LDL at rates more than twentyfold higher than native LDL, through a binding site that recognizes the altered particle but ignores the normal one. Because there is no feedback shutoff, the immune cell keeps engulfing modified LDL until it is bloated with cholesterol. Under the microscope these swollen cells look foamy, which is why they are called foam cells. Foam cells are the cellular seed of an atherosclerotic plaque.
the mechanism is well established in cell and animal studies. Native LDL is cleared on a leash. Modified LDL is swallowed without limit, and the cells that do the swallowing become the building blocks of plaque. This is the part of the story that is not seriously disputed.
What is disputed is how central the oxidation step specifically is in living humans, and intellectual honesty requires saying so plainly. The oxidative modification hypothesis is strongly supported in animal models, but it ran into a wall in human trials: large studies of antioxidant supplements, including vitamin E, largely failed to reduce cardiovascular events or slow the progression of atherosclerosis. Some researchers read those failures as evidence that oxidation is less important in people than the animal work suggested. Others, including Steinberg, who originated the hypothesis, argue that the trials were flawed, that the wrong antioxidants were tested in the wrong doses in the wrong populations, and that many supporting lines of evidence do hold up in humans. The debate is unresolved. What is not in question is that LDL drives atherosclerosis in humans, the entire body of cholesterol-lowering evidence establishes that, and that particle modification and unregulated uptake are real biological events.
The reason this matters now is that the field has moved past thinking of atherosclerosis as a simple plumbing problem in which cholesterol passively clogs a pipe. It is increasingly understood as a chronic inflammatory disease. A foam cell is not an inert lump of stored fat; it is an activated immune cell that releases inflammatory signals, recruits more immune cells, and helps build the unstable plaque that eventually ruptures and causes a heart attack. The strongest proof that inflammation is a genuine driver and not just a bystander came from the CANTOS trial, in which an anti-inflammatory antibody that does not lower cholesterol at all still reduced recurrent cardiovascular events. Lipids start the process; inflammation propagates it.
There is no good evidence that swallowing antioxidant pills protects your arteries, and a post like this is not a license to go buy vitamin E. The honest point is about interpretation: your LDL number is a measure of quantity, not behavior, and it does not capture everything that determines risk. It says nothing about how many atherogenic particles you actually carry, which is why a measure like ApoB often tells a more complete story, and it says nothing about the inflammatory state of your arteries, which is turning out to matter just as much. The concentration on the panel is a starting point, not the whole picture.
Goldstein et al., PNAS 1979
Steinberg, J Lipid Res 2009
Chistiakov et al., 2017
Bleys & Miller, 2006
Ridker et al., NEJM 2017 (CANTOS)
