ALT And AST: The Numbers Behind Every Liver Supplement Study
Open almost any trial of a liver supplement and the first result is an enzyme. Before you can weigh a study you need to know what ALT and AST are, what they are not, and why placebo groups move too.
ALT and AST are enzymes made mainly in the liver, measured in a routine blood test. They are the most common outcome in liver supplement trials because they are cheap and change within weeks, but they are a marker and not the liver itself. Healthy upper limits are lower than many lab printouts suggest, an American College of Gastroenterology guideline puts true healthy ALT at 29 to 33 IU/L for men and 19 to 25 for women, and placebo groups often improve too. A falling enzyme is a reason to run a better trial, not a finding that a capsule works.
- Two enzymes and a blood draw
- Healthy is lower than the printout
- Why supplement trials love ALT
- The gap between a marker and the liver
- Enzymes move for reasons that have nothing to do with a capsule
- Reading a supplement study in five questions
- A worked example: one abstract, five answers
- What this means for this pack
- Sources
Two enzymes and a blood draw
What the letters stand for, and who orders the test.
ALT is alanine aminotransferase and AST is aspartate aminotransferase. MedlinePlus, the US National Library of Medicine’s patient site, describes both as enzymes that are mainly made in the liver, and it says liver function tests are most often used to help find out whether liver disease or damage could be causing certain symptoms. When liver cells are injured, these enzymes leak into the blood, which is why a blood sample can say something about the organ without anyone needing to look at it.
They are part of a small panel. The American College of Gastroenterology’s 2017 guideline on abnormal liver chemistries lists the most commonly ordered as ALT, AST, alkaline phosphatase and bilirubin, and says they should be termed liver chemistries or liver tests. It defines hepatocellular injury as an elevation of AST and ALT out of proportion to alkaline phosphatase, and cholestatic injury as the reverse.
A 2005 review in the Canadian Medical Association Journal uses the same split: a schematic approach that sorts enzyme alterations into predominantly hepatocellular or predominantly cholestatic, then lists the usual causes and first investigations for each. The point for a reader of supplement studies is that these numbers are an ordinary clinical tool with an established way of being read, and it starts with the pattern, not a single value.
Healthy is lower than the printout
Why a result inside the lab’s reference range is not the same as a healthy one.
Most people assume that a number inside the printed range is fine. For ALT the story is less tidy. A 2002 paper in the Annals of Internal Medicine by Daniele Prati and colleagues in Milan pointed out that the usual reference ranges had been set using populations that included people with subclinical liver disease. They studied 6,835 first-time blood donors who tested negative for hepatitis C, and worked out healthy ranges from the group at lowest risk of liver disease.
Their updated upper limits were 30 U/L for men and 19 U/L for women, against the then-current limits of 40 and 30. ALT was independently related to body mass index and to markers of abnormal lipid or carbohydrate metabolism, which means ordinary weight and metabolic health move it. When the new limits were tested against donors who did have hepatitis C, they identified more of the people with active virus (76.3 percent, against 55 percent), at the cost of some specificity (88.5 percent against 97.4 percent).
The American College of Gastroenterology guideline lands in the same place. It says that a true healthy normal ALT level ranges from 29 to 33 IU/L for males and 19 to 25 IU/L for females, that levels above this should be assessed, and that multiple studies have found an elevated ALT is associated with increased liver-related mortality. Laboratories still print their own ranges, and those vary, so do not treat these figures as a personal target. What the two sources show is that the upper end of a printed range can be higher than the level at which a healthy liver sits, and that the boundary between normal and abnormal is a convention.
That has a consequence for supplement studies. If a trial enrols people whose ALT is already high, a fall may take them from clearly raised to modestly raised, and no study of this kind can say what it does for the person’s liver disease. And if it enrols people whose ALT is inside the range, there is little room for a supplement to show any change at all.
Why supplement trials love ALT
Cheap, fast and continuous, which is exactly what a small study needs.
Ask what a trial had to measure to be worth publishing and the reason enzymes dominate is plain. A biopsy is invasive and expensive, and reading it takes a specialist. A scan needs equipment. A blood test costs little, can be repeated every few weeks and produces a number on a scale, which is what statistics like. For a small trial with a small budget it is the obvious primary outcome.
The trials behind the ingredients on this list show it. The NIH-funded silymarin trial in hepatitis C, led by Michael Fried, defined its primary outcome by ALT: a level of 45 U/L or lower, or a fall of at least half. Honda and colleagues’ oral glutathione pilot in fatty liver made ALT its primary outcome. A 2026 set of betaine pilots in Hepatology took the percentage decline in the abnormal part of ALT. And the meta-analyses that pool small trials, one for silymarin in fatty liver and one for berberine, pool ALT and AST first because those are the outcomes most trials report.
None of that is a criticism. A marker is the right way to run a first, small study. The trouble starts when a marker result is written up, in a headline or on a product page, as though it were the outcome that matters. Nobody buys a liver supplement in order to have a lower AST. They buy it because they want a healthier liver, and the distance between those two is the subject of the next part.
The gap between a marker and the liver
Five places in the research where the enzyme and the organ told different stories, or no story at all.
A blood marker is a shadow. It correlates with what is happening in the liver, but it is not the same thing, and the research on supplements shows the gap in several ways.
A fall in enzymes, with no answer on the tissue
A 2021 meta-analysis by Kalopitas and colleagues pooled eight randomised trials of silymarin in fatty liver disease and found lower transaminases than with placebo. The authors were careful to say that further studies were needed to show whether the drop corresponds to improvement in liver histology. A 48-week trial of 700 mg three times a day that did biopsy its patients missed its primary histology goal.
A change in blood measures, with no change in liver fat
The 2026 JAMA Network Open trial of berberine in 337 people measured liver fat directly by CT, found no difference from placebo, and still found LDL cholesterol and a marker of inflammation a little lower. A marker moving does not tell you the organ moved.
A placebo group that improves too
In the silymarin trial in hepatitis C the mean ALT fell by 4.3 U/L on placebo, and in the 48-week fatty liver trial 26.0 percent of the placebo group met the histology target, against 32.7 percent of the silymarin group, a gap too small to tell from chance. Numbers move in people who take nothing active. Commonly cited reasons are regression to the mean, changes in diet and weight, and the attention that comes with being in a trial. Without a comparison group, a fall is uninterpretable.
Small studies without a control
The two oral glutathione pilots in fatty liver, each giving 300 mg a day, reported lower ALT in the people they followed, with no comparison group described. They are honest pilots and the authors said so, but they cannot separate the capsule from the months of diet and exercise that ran alongside.
A big dose for a year with no change in the biopsy
In the 2009 betaine trial in NASH, 20 grams a day for 12 months produced no differences in the activity score or fibrosis stage, and the paper’s conclusion was that betaine did not improve steatosis, though it may protect against worsening steatosis. The tissue is the thing the study was built to look at, and it did not shift.
| Kind of outcome | What it is | What it can tell you | What it cannot |
|---|---|---|---|
| Blood enzymes (ALT, AST) | A blood test | That something changed in the blood | That the liver is healthier, or why the number moved |
| Liver fat by CT or scan | An image of the organ | Whether fat content changed | Whether inflammation or scarring changed |
| Biopsy score | A tissue sample read by a pathologist | Fat, inflammation, ballooning and fibrosis | What happens beyond the trial’s length |
About the product behind this blog
Livpure is a liver supplement in 60-capsule bottles with no Supplement Facts panel in anything supplied to us. Six ingredients are named and not one carries an amount. We publish the gap rather than filling it.
Order NowRead the label firstEnzymes move for reasons that have nothing to do with a capsule
What the guideline says a clinician has to rule out first.
The American College of Gastroenterology guideline is useful here because it lists what has to be considered when a liver chemistry is raised. For hepatocellular injury the evaluation includes testing for viral hepatitis A, B and C, assessing non-alcoholic fatty liver disease and alcoholic liver disease, and screening for hereditary hemochromatosis, autoimmune hepatitis, Wilson’s disease and alpha-1 antitrypsin deficiency. It also says that a history of prescribed and over-the-counter medicines should be sought.
Two practical things follow. The first is that an enzyme result is the start of a question, not the end of one, and only someone who can see the whole picture should interpret a raised value. The second is that supplements belong in that medicine history. A capsule that you take every day counts as part of the list of things a clinician needs to know about, and it is easily left out because it does not feel like a drug.
If you take a liver supplement of any kind and you are having liver tests, say so. That applies to a product like Livpure and equally to any other. It is also a reason not to try to read a single result yourself. Yellowing of the skin or eyes, dark urine, pale stools or ongoing pain under the right ribs are reasons to be seen promptly, and the timing of a supplement is not a reason to wait.
Reading a supplement study in five questions
A checklist that works on any trial, including the ones behind a product page.
- Who took part? Healthy people, or people with a diagnosed liver condition? A result in one group does not carry to the other.
- Compared with what? A placebo, a different treatment, or nothing? Without a comparison group, a fall in a number cannot be credited to the capsule.
- What was measured? A blood marker, an image or a biopsy? Look for the word primary, which marks the outcome the study was built to test.
- How much, for how long? The dose in the trial is only useful if you can compare it with a dose on a label. Trials that used a gram or more a day cannot be matched to a product that prints no amount.
- How large and how sure? Look at the number of people and at the confidence interval. A wide interval that includes zero means the study could not tell an effect from chance.
Run those five on the studies named on this page and most of them come out as promising but early. That is the honest description of most of the evidence on supplement ingredients for the liver, and it is not a scandal. It is what evidence in this area looks like when the trials are small, short and use markers.
A worked example: one abstract, five answers
The five questions, run on a real trial so you can see how it goes.
Take the silymarin trial in hepatitis C from 2012, which is a good specimen because it was well run and its abstract is short.
Who took part? 154 adults with chronic hepatitis C whose earlier interferon treatment had failed and whose ALT was 65 U/L or higher. That is a group with a viral liver disease and raised enzymes, so the result says nothing about a healthy adult and not much about fatty liver.
Compared with what? Three arms, randomly assigned: 420 mg of silymarin, 700 mg, or a matching placebo, each three times a day. A placebo arm is what lets the result mean anything.
What was measured? The primary outcome was ALT reaching 45 U/L or lower, or falling under 65 U/L with at least a 50 percent decline. Secondary outcomes were ALT change, viral load and quality of life. All are markers or questionnaires; no biopsy.
How much, for how long? 1,260 mg or 2,100 mg a day for 24 weeks. A dose that size can be checked against a label that prints an amount, and cannot be against one that does not.
How sure? Two people in each arm met the primary outcome, which is 3.8 to 4.0 percent, with wide intervals around each figure. The average ALT fell by 4.3 U/L on placebo and by 14.4 or 11.3 on silymarin, a difference the trial reported as not statistically significant. The honest reading is that the trial could not tell silymarin from placebo.
That took five short answers and it did more than the sentence a headline would have offered. A page that said silymarin lowered ALT would be describing the 14.4 and 11.3 and leaving out the 4.3 and the P value, which is the only way to make that trial sound like a win.
What this means for this pack
The label part of the same argument.
None of the studies discussed here tested Livpure. They tested single ingredients, at stated doses, in defined groups. The pack itself prints no Supplement Facts panel, no amount for any of its six named ingredients and no serving size, so no dose in any of these trials can be set against it. The Supplement Facts page lists everything missing.
If you see Livpure described, anywhere, as lowering liver enzymes or improving liver tests, ask two questions. Which study, of this product? And measured how? We know of none that fits, and we have not written or implied that one exists. What is true is narrower: some ingredients on the list have been tested, mostly as single compounds and mostly with markers, and the results are a mixed picture.
For the ingredient-level detail, berberine and the fatty liver trials and molybdenum are the two companion posts, and the post on the one document explains why the panel is the part of a label that can be checked.
Sources
Every study, label and guideline named above, with the record it was checked against.
- Kwo PY, Cohen SM, Lim JK. ACG clinical guideline: evaluation of abnormal liver chemistries. Am J Gastroenterol. 2017;112(1):18-35. https://pubmed.ncbi.nlm.nih.gov/27995906/
- Giannini EG, Testa R, Savarino V. Liver enzyme alteration: a guide for clinicians. CMAJ. 2005;172(3):367-379. https://pubmed.ncbi.nlm.nih.gov/15684121/
- Prati D, Taioli E, Zanella A, et al. Updated definitions of healthy ranges for serum alanine aminotransferase levels. Ann Intern Med. 2002;137(1):1-10. https://pubmed.ncbi.nlm.nih.gov/12093239/
- MedlinePlus, U.S. National Library of Medicine. Liver function tests. https://medlineplus.gov/lab-tests/liver-function-tests/
- Fried MW, Navarro VJ, Afdhal N, et al. Effect of silymarin (milk thistle) on liver disease in patients with chronic hepatitis C unsuccessfully treated with interferon therapy: a randomized controlled trial. JAMA. 2012;308(3):274-282. https://pubmed.ncbi.nlm.nih.gov/22797645/
- Wah Kheong C, Nik Mustapha NR, Mahadeva S. A randomized trial of silymarin for the treatment of nonalcoholic steatohepatitis. Clin Gastroenterol Hepatol. 2017;15(12):1940-1949.e8. https://pubmed.ncbi.nlm.nih.gov/28419855/
- Kalopitas G, Antza C, Doundoulakis I, et al. Impact of silymarin in individuals with nonalcoholic fatty liver disease: a systematic review and meta-analysis. Nutrition. 2021;83:111092. https://pubmed.ncbi.nlm.nih.gov/33418491/
- Honda Y, Kessoku T, Sumida Y, et al. Efficacy of glutathione for the treatment of nonalcoholic fatty liver disease: an open-label, single-arm, multicenter, pilot study. BMC Gastroenterol. 2017;17(1):96. https://pubmed.ncbi.nlm.nih.gov/28789631/
- Irie M, Sohda T, Anan A, et al. Reduced glutathione suppresses oxidative stress in nonalcoholic fatty liver disease. Euroasian J Hepatogastroenterol. 2016;6(1):13-18. https://pubmed.ncbi.nlm.nih.gov/29201718/
- Abdelmalek MF, Sanderson SO, Angulo P, et al. Betaine for nonalcoholic fatty liver disease: results of a randomized placebo-controlled trial. Hepatology. 2009;50(6):1818-1826. https://pubmed.ncbi.nlm.nih.gov/19824078/
- Lim AS, Cruz SN, Uddin AA, et al. Pilot trials of oral betaine in participants with metabolic dysfunction-associated steatotic liver disease and elevated alanine aminotransferase. Hepatology. 2026;83(6):1515-1528. https://pubmed.ncbi.nlm.nih.gov/40758380/
- Nie Q, Li M, Huang C, et al. The clinical efficacy and safety of berberine in the treatment of non-alcoholic fatty liver disease: a meta-analysis and systematic review. J Transl Med. 2024;22(1):225. https://pubmed.ncbi.nlm.nih.gov/38429794/
- Lei L, Wang B, Zhao L, et al. Berberine and adiposity in diabetes-free individuals with obesity and MASLD: a randomized clinical trial. JAMA Netw Open. 2026;9(1):e2554152. https://pubmed.ncbi.nlm.nih.gov/41543854/