Alpha-ketobutyrate
Alpha-ketobutyrate, an intermediate of the transsulfuration pathway
Written by Aaron CuhaReviewed Sep 2026
Also known as: 2-oxobutyrate, AKB, alpha-KB, 2-ketobutyric acid
One lifespan paper, in Caenorhabditis elegans. In humans the closely related metabolite alpha-hydroxybutyrate is not a longevity marker at all: it is an early marker of insulin resistance that predicted worsening glucose tolerance in 3,841 non-diabetic people across two cohorts. No trial of supplementing alpha-ketobutyrate in humans was located.
Overview
Alpha-ketobutyrate is sold on the strength of a single well-executed worm paper, and the human data that exist about the same corner of metabolism point in an awkward direction.
The worm paper is real and its mechanism is worked out in unusual detail. Supplementing alpha-ketobutyrate extended lifespan in wild-type C. elegans. The route ran through lactate dehydrogenase raising NAD+ production, then SIR-2.1, the worm sirtuin, then enhanced peroxisome function and biogenesis, then peroxisomal fatty acid beta-oxidation generating hydrogen peroxide, then activation of SKN-1, the worm equivalent of NRF2, which drove autophagy and lysosomal gene expression. The same paper reported delayed senescence in fibroblast cells through a parallel SIRT1 to ACOX1 to hydrogen peroxide to NRF2 route.
That is a worm and a dish. There is no mouse lifespan data for this compound that this entry could locate, and no human supplementation trial of any kind.
The human evidence concerns the same metabolic node from the other direction. Alpha-ketobutyrate is produced by the transsulfuration pathway when homocysteine is committed to cysteine synthesis, and it is reduced to alpha-hydroxybutyrate by lactate dehydrogenase, consuming NADH in the process. Alpha-hydroxybutyrate is therefore a readout of transsulfuration flux and of cellular redox state, and it has been studied extensively in people, because metabolomic screening picked it out as an early marker of insulin resistance. In 1,261 non-diabetic participants in the RISC study and 2,580 in the Botnia Prospective Study, alpha-hydroxybutyrate was a positive correlate of insulin resistance and an independent predictor of incident dysglycaemia over three years and of type 2 diabetes over 9.5 years, with adjusted odds ratios of about 1.25 per standard deviation in both cohorts.
So the metabolic signature that the supplement is meant to create is, in humans, a signature that goes up in people heading toward diabetes. That is not proof that supplementing it is harmful. It is a reason to want a human trial before assuming it is beneficial, and there is not one.
Mechanism of action
Alpha-ketobutyrate sits at the end of the transsulfuration pathway. When cystathionine is cleaved to make cysteine, alpha-ketobutyrate is released as the by-product, so its production rises whenever flux from homocysteine to cysteine rises. It is then either decarboxylated to propionyl-CoA and fed into the TCA cycle, or reduced to alpha-hydroxybutyrate by lactate dehydrogenase. That reduction step is the mechanism claimed for the worm result. Converting alpha-ketobutyrate to alpha-hydroxybutyrate oxidises NADH to NAD+, raising the NAD+ to NADH ratio, which is the input that sirtuins respond to. In C. elegans this was shown to run through SIR-2.1 to peroxisome biogenesis, to peroxisomal beta-oxidation, to hydrogen peroxide as a signal, to SKN-1 activation and then autophagic and lysosomal gene expression. The same chemistry explains why alpha-hydroxybutyrate rises in insulin resistance in people: both increased transsulfuration flux under oxidative stress and a shifted cellular redox state push the reduction forward. The molecule is a sensor of metabolic state, which makes interpreting what happens when you add it from outside genuinely uncertain.
Human evidence
No human has been given alpha-ketobutyrate in a published trial that this entry could locate. The human data are observational and concern the endogenous metabolite rather than a supplement, and they associate this branch of metabolism with worsening glucose tolerance rather than with health or longevity.
- No randomised or open-label trial of alpha-ketobutyrate supplementation in humans was located.
- In 1,261 non-diabetic adults followed 3 years and 2,580 followed 9.5 years, alpha-hydroxybutyrate, the reduction product of alpha-ketobutyrate, independently predicted incident dysglycaemia and type 2 diabetes at about 1.25 odds per standard deviation.
- The same metabolite correlates positively with insulin resistance and inversely with indices of beta-cell function derived from an oral glucose tolerance test.
- In INS-1e beta cells, alpha-hydroxybutyrate inhibited glucose-induced insulin release.
- No human study has measured lifespan, healthspan, NAD+ status or any ageing endpoint in response to alpha-ketobutyrate.
What this does not tell you: None of the human data is interventional, so it cannot tell you what happens when you add the molecule from outside. A metabolite that rises in a disease state is not thereby a cause of that state, and raised alpha-hydroxybutyrate in insulin resistance most plausibly reflects increased transsulfuration flux and a shifted redox state rather than damage done by the molecule. But the inference runs both ways: nobody can tell you that pushing the same pathway upward is beneficial either, because nobody has tried it in a person and measured anything.
Reading the research record
Two clarifications belong at the top of any page about this compound.
First, alpha-ketobutyrate is not alpha-ketoglutarate. They are different molecules with different chemistry and separate evidence bases, and this site covers alpha-ketoglutarate separately under calcium AKG. The abbreviations AKB and AKG differ by one letter and are confused constantly, including in retail listings.
Second, the evidence here is one C. elegans lifespan paper with a carefully worked mechanism, plus cell culture. That is a legitimate reason for a researcher to be interested and it is not a reason for a person to take something. The gap between a worm and a person is the largest gap in this batch, and it is not bridged by the quality of the mechanism, which is a description of how the effect happened in the worm rather than evidence that it happens in people.
The interesting complication is that this molecule is not novel to human biology. It is made constantly by the transsulfuration pathway and it has been measured in thousands of people, because its reduction product turned out to be a good early warning sign for diabetes. That is the opposite of the usual situation on this site, where a compound is sold with no human data at all. Here there is a great deal of human data about the endogenous molecule, and it says this pathway runs higher in people whose glucose tolerance is getting worse. Whether supplementing the upstream keto acid would mimic that state or relieve it is an open question that a single pharmacokinetic and glucose tolerance study would begin to answer, and nobody has published one.
This archive's stated position on supplements is that you take something because a number on your bloodwork is out of range, and that you retest and stop if the number does not move. Applying that rule to this group is uncomfortable, because for most of them there is no deficiency state to correct and therefore no marker that tells you whether the bottle is doing anything. Where a compound here does move a readable number, the number is a surrogate rather than a deficiency, so moving it is not the same as fixing something that was broken.
The evidence, charted
Fig. 1 · evidence composition
2of 3 citations (67%) are in people
Counted from the citation list on this page. The Human count is the same number shown in the badge at the top. Both understate any literature larger than the sources we cite.
Fig. 2 · evidence over time
Evidence spans 3 distinct years, 2010 to 2023, counted from the citation list 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 jurisdictions shown. A jurisdiction's classification is a regulatory fact, not a verdict on the science; see Legal status below for the full text and any notes.
Key studies & citations
- Animal2023
The metabolite alpha-ketobutyrate extends lifespan by promoting peroxisomal function in C. elegans.
Supplementing alpha-ketobutyrate extended lifespan in wild-type Caenorhabditis elegans. The mechanism traced through lactate dehydrogenase LDH-1 raising NAD+ production, SIR-2.1 mediating enhanced peroxisome function and biogenesis, raised acox-1.2 expression driving peroxisomal fatty acid beta-oxidation and hydrogen peroxide formation, and SKN-1 (the worm NRF2) driving autophagic and lysosomal gene expression. The paper also reports delayed cellular senescence in fibroblast cells through a SIRT1 to ACOX1 to hydrogen peroxide to NRF2 route. Worms and cells; no mammal lifespan data in this paper.
Nature Communications - Human2010
alpha-hydroxybutyrate is an early biomarker of insulin resistance and glucose intolerance in a nondiabetic population.
The metabolomic screen that identified alpha-hydroxybutyrate, the reduction product of alpha-ketobutyrate, as an early marker of insulin resistance and glucose intolerance in non-diabetic people. This is the human context that the lifespan claim sits inside: in people, this branch of metabolism is elevated in the direction of metabolic disease rather than health.
PLoS One - Human2013
Early metabolic markers of the development of dysglycemia and type 2 diabetes and their physiological significance.
1,261 non-diabetic participants in the RISC study followed 3 years and 2,580 in the Botnia Prospective Study followed 9.5 years. Alpha-hydroxybutyrate was a positive correlate of insulin resistance and an independent predictor of incident dysglycaemia or type 2 diabetes, adjusted odds ratios 1.25 (95 percent CI 1.00 to 1.60) and 1.26 (1.07 to 1.48) per standard deviation, independent of familial diabetes, sex, age, BMI and fasting glucose. In INS-1e cells alpha-hydroxybutyrate inhibited glucose-induced insulin release.
Diabetes
Frequently asked questions
Is alpha-ketobutyrate the same as alpha-ketoglutarate?
No. They are different molecules with different roles and separate literatures. Alpha-ketoglutarate is a TCA cycle intermediate covered separately on this site; alpha-ketobutyrate is a by-product of the transsulfuration pathway. The abbreviations AKB and AKG are routinely mixed up in product listings.
Does alpha-ketobutyrate extend lifespan?
In Caenorhabditis elegans, yes, in one 2023 paper with a detailed mechanism running through NAD+, the worm sirtuin SIR-2.1, peroxisome biogenesis and the worm NRF2 homologue. There is no mouse lifespan data located for this compound and no human data of any kind.
Does it raise NAD+ in people?
Unknown. The NAD+ mechanism is established in worms, where reducing alpha-ketobutyrate to alpha-hydroxybutyrate oxidises NADH and raises the NAD+ to NADH ratio. Nobody has measured NAD+ in a human given this compound.
Why is it linked to insulin resistance?
Its reduction product, alpha-hydroxybutyrate, was picked out by metabolomic screening as an early marker of insulin resistance and glucose intolerance, and in two cohorts totalling 3,841 non-diabetic people it independently predicted worsening glucose tolerance. That most likely reflects increased transsulfuration flux and a shifted redox state rather than harm from the molecule itself, but it does mean the human association with this pathway runs toward metabolic disease, not away from it.
Is there a dose that has been tested in humans?
No. No human supplementation trial was located for this entry, so there is no tested dose, no human pharmacokinetic profile and no safety data in people.