25-Hydroxycholesterol dosage and evidence
Written by Aaron CuhaReviewed Sep 2026
The short answer
25-Hydroxycholesterol is a cholesterol byproduct your body makes itself. A 2025 study found it made old mice's main artery less stiff, about as much as killing their worn-out cells with genes. Other mouse work points the opposite way in the brain, where the same molecule drives swelling and damage.
Evidence grade for 25-Hydroxycholesterol: Preliminary. The rule: studied in people, but no published study has had people take it. The sum on this page: 1 human study where nobody was given it. A grade counts how much has been done to people, not whether it works.
- People given it
- 0
- Human studies
- 0
- Found nothing
- 0
Dose
No human dose established
No published study on this page has given this compound to people and reported a result.
1 human study where nobody was given it
2 effects reported, 2 unwanted, by people using it, not a trial
Goal pages: Injury, healing and recovery, Heart and circulation, Immune system and inflammation, Gut health
In plain English
In plain English, from Aaron
This is how I would explain it to a friend. The evidence, with the numbers, is further down the page.
25-Hydroxycholesterol is a molecule your body makes from cholesterol when your immune system is fired up. A 2025 mouse study said it made old arteries less stiff. It is sold only as a lab chemical. It is not approved for anything.
What people take it for
- Less stiff arteries.
- Clearing worn-out cells.
What studies in people showed
Nobody has given it to a person. It has only been measured in people's blood and spinal fluid. In old mice, five days of it made the main artery less stiff. But in other mice, the same molecule made brain damage and clogged arteries worse. Nobody has repeated the good result.
What people report
Reports, not study results
The good
- We have not collected user reports on this one yet.
The bad
- In mice, it drove brain damage in one model and artery damage in another.
- Nobody knows what taking it would do to a person.
Where these come from: The points above are from the mouse studies on this page. There are no studies in people and we have no forum reports.
My bottom line
One mouse paper says good, two say harm. A molecule your immune system uses to turn up swelling is not something I would take every day.
An opinion, not a finding. I am a coach, not a doctor.
What it has been measured to do
Animal and lab work, not yet tested in people
Real results, but from animals or cells, not people. What works in a mouse often does not work the same way in a person. Nobody can patent this, so nobody would ever earn back the cost of a study in people. That is usually why there is none. The record on this one is set out below.
- Inflammation1 animal or lab study
- Heart attacks and strokes1 animal or lab study
34 of the 36 indexed goals have no study of any kind behind 25-Hydroxycholesterol
No study in people, animals or cells on this page reports a result for these. That does not prove 25-Hydroxycholesterol does nothing for them. It does mean anything you have heard about 25-Hydroxycholesterol and one of these did not come from a study cited here.
Show full evidence
What is 25-Hydroxycholesterol?
25-Hydroxycholesterol is a cholesterol byproduct your body makes itself. A 2025 study found it made old mice's main artery less stiff, about as much as killing their worn-out cells with genes. Other mouse work points the opposite way in the brain, where the same molecule drives swelling and damage.
25-Hydroxycholesterol is made from cholesterol by an enzyme that immune cells switch on when they fight. It is a signal the body makes, not a drug. It helps control how much cholesterol cells make, the body's antiviral alarm, and swelling signals.
Nobody has given it to a person in a published study. It has only been measured in people. For example, it has been measured in blood and spinal fluid in people with multiple sclerosis and other brain diseases. No clean-up drug has improved health in a proper study in people, and this molecule has never been given to a person at all.
In mice, the clean-up claim is new and narrow. A 2025 study used old mice bred so their worn-out cells could be killed with a drug switch. It compared 25-hydroxycholesterol with that switch. Five days of 25-hydroxycholesterol made the main artery less stiff, about as much as killing the worn-out cells. In artery tissue from mice whose worn-out cells were already gone, it made no further difference. The authors took that to mean it works by acting on worn-out cells. A stiffening protein fell and a stretchy one rose.
In other mice, the same molecule points the other way. In mice carrying a harmful human brain protein called tau, removing the gene that makes 25-hydroxycholesterol sharply cut age-related brain damage and swelling. In mice with clogged arteries, 25-hydroxycholesterol from immune cells made artery swelling and damage worse. A molecule that helps the artery in one kind of mouse, and harms the brain and artery wall in others, is not something to take as a supplement based on one paper.
How does 25-Hydroxycholesterol work?
Shown in mice and cells: 25-hydroxycholesterol is made by an enzyme called cholesterol 25-hydroxylase. It tells cells to make less cholesterol and it changes antiviral and swelling signals. In the artery study, the clean-up reading rests on one test: it did nothing extra in arteries from mice whose worn-out cells had already been killed. It also lowered a protein thought to be its target. In the brain and clogged artery mouse studies, the same molecule turns up swelling signals. None of this has been checked in a person given it.
What have studies in people found about 25-Hydroxycholesterol?
None as a treatment. 25-Hydroxycholesterol has been measured in human blood, spinal fluid and clogged artery tissue. But no published study has given it to a person, and no study is registered.
- Studies have measured 25-hydroxycholesterol in blood and spinal fluid in people with brain diseases, and in clogged arteries. These only measure what the body already makes.
- No study of how the body handles it, no dosing study, and no registered study giving it to people was found.
What this does not tell you: Measuring a molecule the body makes, in sick people, tells you its level changes with disease. It does not tell you which causes which. And it certainly does not tell you what taking more of it would do. The mouse research goes both ways depending on the body part, which is the best reason not to guess.
The state of the research
This is a one-paper clean-up claim, for a molecule with a large and conflicting body of research on swelling. The 2025 artery result is careful work. It compares the molecule with killing worn-out cells by genes in the same kind of mouse, which is a tougher test than most clean-up papers use. It is also five days of treatment in old mice, and nobody has repeated it.
Against it sit two solid mouse papers where 25-hydroxycholesterol, or the enzyme that makes it, does harm. One found brain damage in a mouse model of dementia. The other found clogged, damaged arteries. A molecule the immune system makes to turn up swelling is an awkward choice for a daily supplement. And nobody has given it to a person to find out.
The evidence, in charts
Fig. 1a · how many people
1study in people cited, but none says how many people took part
number of people not stated
We do not draw a total, because none of the studies in people on this page gives one. Read the sources below for what each study measured.
We read the number of people from the source lines on this page. Where a line gives no number, we count nothing for it. We do not guess.
Fig. 1b · evidence mix
1 of 4 sources here is a study in people. The rest are not.
- Study in people · done in people125%
- Animal study · done in animals375%
Counted from the list of sources on this page. It counts only what we cite, so there may be more studies out there. A review counts once, however many studies it sums up.
Fig. 2 · evidence over time
The studies cover 4 different years, 2017 to 2025, counted from the list of sources on this page.
Fig. 3 · legal status at a glance
US
Not approved
UK
Not approved
AU
Not approved
CA
Not approved
Not approved in any of the four countries shown. This is what the law says, not a verdict on the science. See Legal status below for the full text and any notes.
Fig. 4 · how much does what
Nobody has tested different amounts in people
This chart would show how the effect changes as the amount goes up. For this compound, nobody has measured that in people. So we leave it empty. We will not borrow an animal chart and pretend it works the same in people.
Fig. 5 · what the molecule is
- Kind of compound
- Small molecule
- Molecule weight
- Not on file
- Half-life
- None on file
- Chain length
- None on file
No amino acid sequence is on file for 25-Hydroxycholesterol, which is expected: a small molecule is not built from amino acids.
The studies we cite
- Study in people2017Reduced Plasma Levels of 25-Hydroxycholesterol and Increased Cerebrospinal Fluid Levels of Bile Acid Precursors in Multiple Sclerosis Patients
Nobody was given anything in this study. Researchers measured more than 20 cholesterol-type molecules in blood and spinal fluid from people with multiple sclerosis, people with other brain and inflammatory diseases, and healthy people. 25-hydroxycholesterol was higher in the spinal fluid of people with suspected immune attacks on the brain. That measures what the body already makes. It tells you nothing about what happens if you put this into a person.
Human measurement study. More than 20 non-esterified sterols were quantified by mass spectrometry in plasma and cerebrospinal fluid from patients with multiple sclerosis, other inflammatory and neurodegenerative disease, and controls. 25-Hydroxycholesterol was elevated in cerebrospinal fluid in suspected autoimmune inflammatory disease. Nobody was given the compound.
- Animal study2025Late Life Supplementation of 25-Hydroxycholesterol Reduces Aortic Stiffness and Cellular Senescence in Mice
In old mice. In mice aged 22 to 26 months, five days of 25-hydroxycholesterol made the main artery less stiff, about as much as killing worn-out cells with a gene switch. A stiffening protein fell and a stretchy one rose. In arteries from mice whose worn-out cells were already gone, it made no further difference, which the authors took to mean it acts through worn-out cells.
Old p16-3MR mice aged 22 to 26 months. Five days of 25-hydroxycholesterol reduced aortic pulse wave velocity (P = 0.002), similar to genetic clearance of p16-positive cells with ganciclovir, with lower collagen-1 and higher alpha-elastin. Aortic rings from ganciclovir-treated mice showed no further reduction in elastic modulus, which the authors read as senescence-mediated action.
- Animal study2024Cholesterol 25-hydroxylase mediates neuroinflammation and neurodegeneration in a mouse model of tauopathy
In mice, and it points the other way. In mice carrying a harmful form of the human brain protein tau, removing the gene that makes 25-hydroxycholesterol sharply cut age-related brain damage and swelling, and calmed the brain's immune cells.
Mouse, and it points the opposite way. In PS19 mice expressing mutant human tau, deleting Ch25h and reducing 25-hydroxycholesterol markedly reduced age-dependent neurodegeneration and neuroinflammation, with suppressed proinflammatory microglial signalling on single-nucleus sequencing.
- Animal study2023Macrophage-Derived 25-Hydroxycholesterol Promotes Vascular Inflammation, Atherogenesis, and Lesion Remodeling
In mice. In mice with clogged arteries, 25-hydroxycholesterol made by immune cells made artery swelling and damage worse. It was also measured in human artery tissue, but only measured. This is a harm result in the same part of the body as the artery stiffness study.
Mouse atherosclerosis models, with 25-hydroxycholesterol and CH25H expression also measured in human lesions. Macrophage-derived 25-hydroxycholesterol promoted vascular inflammation and lesion remodelling, a harm direction in the same organ system as the aortic stiffness study.
Common questions
Has 25-Hydroxycholesterol been tested in people?
Not in a completed trial cited here. 1 human study where nobody was given it. 25-Hydroxycholesterol is a cholesterol byproduct your body makes itself. A 2025 study found it made old mice's main artery less stiff, about as much as killing their worn-out cells with genes. Other mouse work points the opposite way in the brain, where the same molecule drives swelling and damage.
What is the 25-Hydroxycholesterol dosage?
No human dose established. No published study on this page has given this compound to people and reported a result. 1 human study where nobody was given it
Is 25-Hydroxycholesterol FDA-approved?
Not approved for any use. The body makes it naturally, and it is sold as a lab chemical. No human study is registered.
Has anyone taken 25-hydroxycholesterol as a supplement in a study?
No published study has given it to a person, for ageing or anything else, and no study is registered. The data in people only measure the natural molecule in blood, spinal fluid and tissue.
What did the 2025 mouse study show?
In old mice bred so worn-out cells could be killed with a drug switch, five days of 25-hydroxycholesterol made the main artery less stiff, about as much as killing the worn-out cells. The stiffening and stretchy proteins in the artery also changed for the better. It is one study, five days long, in mice.
Is 25-hydroxycholesterol anti-inflammatory or pro-inflammatory?
Both, depending on the body part and the study. In a mouse model of dementia, removing the enzyme that makes it cut brain damage and swelling. In mice with clogged arteries, the version made by immune cells made artery swelling and damage worse. The good artery result sits next to these, not above them.