The Eight-Year Question: What Alpha-Ketoglutarate Did for Ageing Mice, What One Human Study Claimed, and the Trial Built to Test It

Chapter 1

The Number That Travelled Without a Control Group

In late 2021, a short paper in the journal Aging carried a number that travelled much further than the paper itself. Forty-two people had been taking a supplement built around a molecule called alpha-ketoglutarate, usually shortened to AKG, for about seven months. When their blood was tested again, their biological age, estimated from chemical marks on their DNA, had fallen by an average of eight years.

Eight years is the kind of number that ends up in headlines, podcasts and product pages, and it did. If you have read anything about AKG, there is a good chance it reached you through that number.

Yet the study had a gap that matters more than the number. Everyone in it was taking the supplement. Nobody was taking a dummy capsule, and nobody was simply tested twice without taking anything at all.

This article is about that gap, and about the molecule on the other side of it. AKG is not a fringe compound. Your own cells make it all day long, and in ageing mice it produced one of the more convincing results in longevity research. A placebo-controlled human trial built specifically to test it is now under way.

By the end, you will know what AKG does in your cells, what it did for old mice, why the human headline still needs checking, and five questions that let you judge the next "years younger" claim you come across, whoever makes it.

Section 1

Forty-Two People and One Big Average

The 2021 paper was a retrospective analysis. The researchers did not recruit volunteers and hand out capsules. They looked back at people who had already chosen to take an AKG-based formulation sold as Rejuvant, and who had taken a commercial DNA-methylation test before they started and again after somewhere between four and ten months.

A DNA-methylation test reads small chemical tags, called methyl groups, that sit on particular spots of your DNA. The pattern of those tags shifts steadily as people get older, so researchers have built algorithms, often called epigenetic clocks, that estimate age from the pattern. When the estimate comes out higher than your birthday suggests, you are said to be biologically older; lower, biologically younger.

Across the 42 people, the average estimate fell by about eight years between the two tests. The authors also reported that most participants moved in the same direction, and that the people who were older, by calendar or by test, appeared to gain the most.

One average, read up close: what a single before-and-after number can and cannot tell you.

Section 2

Who Measured, and Who Sold

Like many early studies in this field, the paper came from people close to the product. Several authors worked for the company that provides the DNA test, and others for the company that makes the formulation. This was disclosed in the paper, and it is common in early-stage research, where companies often generate the first data on their own products.

It does not make the result false. It does mean the result deserves the same independent check any of us would want before trusting a claim from someone with something at stake.

To their credit, the authors said exactly that. In their own summary they wrote that continued testing, "particularly in a placebo-controlled design", is required. That is the right instinct, and it is where this story is heading.

Section 3

The Bathroom-Scale Retest

Here is why a comparison group matters so much, using something everyone has done.

Imagine you step on the bathroom scale one morning after a salty dinner and a poor night's sleep. The number is higher than you expected, so you decide to change something. A week later you weigh yourself again, and the number is lower. Some of that drop may be your new habit. Some of it is simply that the first reading caught you on a heavy day.

Statisticians call this regression to the mean. When people are selected, or select themselves, because a reading came out unusually high, a second reading tends to come back closer to their normal level, even if nothing has changed. Biological-age tests are not perfectly precise either: the same blood can give somewhat different estimates on different occasions.

Now add two more ingredients. People who start a new supplement often change other things at the same time, such as sleep, exercise or diet. And people who received a disappointing first result are more likely to be motivated to do something about it.

Put together, these effects can push an average down on a retest with no supplement involved at all. Interestingly, they would also make the people who started highest appear to improve most, which is one of the patterns the 2021 paper reported. That pattern is what a real effect could look like. It is also what regression to the mean looks like. Without a comparison group, the two cannot be told apart.

None of this says the eight-year result is wrong. It says the result, on its own, cannot tell us what AKG adds. That is a question about evidence, not about AKG, and to see why scientists still take AKG seriously, we need to look at what it does inside a cell.

🔒 LOCKED: EXCLUSIVE READER REWARD

There is a private, unadvertised reader reward waiting at the end of this article.

Read the next three chapters closely. Score at least 4 out of 5 on the Final Master Quiz at the bottom of the page and we will unlock a reward chosen for exactly the reader who has just understood this science, together with a private code that never appears on our public pages. Valid 20 October to 3 November 2026.

The answers are all in the chapters ahead…

Chapter 2

A Molecule Your Mitochondria Make All Day Long

Before asking whether AKG can change how we age, it helps to know that you already have it. Alpha-ketoglutarate is not a plant extract or an exotic compound. It is one of the ordinary working parts of your own metabolism, made inside your cells every minute of every day.

That is part of what makes it interesting. Many longevity candidates are foreign molecules we hope will do something useful. AKG is a molecule the body already relies on, and researchers want to know what happens when there is more of it around.

Section 1

Where AKG Sits

Inside almost every cell are mitochondria, the structures that turn the food you eat into usable energy. At their centre runs a loop of chemical reactions called the Krebs cycle, also known as the citric acid or TCA cycle. Fuel goes in, and each turn of the loop passes energy on to the machinery that makes ATP, the cell's energy currency.

AKG is one of the stops on that loop, a Krebs-cycle intermediate. But it does not stay put. A 2021 review by researchers at the National University of Singapore describes AKG as a molecule with many jobs: it helps manage the body's nitrogen and ammonia balance by linking energy metabolism to amino acids, it has antioxidant activity, and it takes part in epigenetic and immune regulation, the systems that decide which genes are switched on and how the body handles inflammation.

The same review notes that AKG levels change with fasting, exercise and age. That combination, a central metabolite whose levels shift with exactly the things that influence ageing, is what first drew longevity researchers to it.

AKG is made inside mitochondria as part of the Krebs cycle, the loop that turns food into usable energy.

Section 2

The Worm Result

The first striking lifespan result came in 2014 from a team at the University of California, Los Angeles, published in Nature. They added AKG to the environment of the tiny roundworm C. elegans, one of biology's standard models for studying ageing, and the worms lived longer as adults.

The more important part of the paper was the how. Using a technique that finds which proteins a small molecule binds to, the team showed that AKG attaches to part of ATP synthase, the enzyme that produces most of a cell's ATP, and gently slows it down. Treated worms, and treated mammalian cells in a dish, made a little less ATP and used less oxygen.

That sounds like the opposite of what you would want. But earlier research had already shown that partially, not completely, dialling down energy production can extend lifespan in worms. The team also found that the effect depended on TOR, a growth-signalling pathway that is one of the most studied levers in ageing biology.

Two more observations completed the picture. Worms' own AKG levels rose when they were starved of food, and worms already living on a restricted diet gained nothing extra from added AKG. Both point to AKG sitting somewhere on the same biological route as dietary restriction, the most reliable way of extending lifespan in laboratory animals.

Worms are not people. They are useful because they live for only a few weeks, which lets researchers test ideas quickly. The real question was whether anything similar would hold in a mammal.

Section 3

From Worms to Old Mice

In 2020, a team at the Buck Institute for Research on Aging in California published the answer in Cell Metabolism. They gave mice AKG in the form of a calcium salt, calcium alpha-ketoglutarate (Ca-AKG), mixed into their food.

One design choice made the study especially relevant. The mice did not start as youngsters. They began at 18 months of age, firmly middle-aged for a laboratory mouse. That matters because most people who think about longevity compounds are not 20; they are 50 or 60 and wondering whether starting now can still make a difference.

The treated mice lived longer, by about 12% on average according to the institute's summary. Their blood showed lower levels of inflammatory signalling molecules and higher levels of IL-10, a messenger that helps calm inflammation. The authors proposed that this shift in inflammation explained much of the benefit.

But the lifespan figure was not the headline result. The headline was how the mice aged along the way, and that deserves its own chapter.

Chapter 3

The Months That Matter More Than the Maximum

Ask people whether they want to live to 100 and many hesitate. Ask whether they would like their last ten years to be active, independent and clear-headed, and almost everyone says yes. The question that matters to most of us is not only how long, but how well.

That is exactly the distinction the Buck Institute team set out to measure, and it is where their AKG result became genuinely unusual.

Section 1

How You Score a Frail Mouse

You cannot ask a mouse how it feels, so ageing researchers use a frailty index. Every few weeks, a trained observer works through a checklist of signs that accumulate with age: the condition of the coat, the way the animal walks, a hunched spine, grip strength and other visible changes. Each problem adds a point. The more points, the frailer the mouse.

This is close to how geriatricians assess frailty in older people, by counting accumulated health deficits rather than looking for a single disease. It turns "healthy ageing", a vague phrase, into something you can actually measure over time.

On this measure, the AKG-fed mice did markedly better than the control mice. In the Buck Institute's summary, healthspan measures improved by more than 40%, a much larger effect than the gain in lifespan. The researchers put it in a single line: "the reduction in frailty was more dramatic than the increase in lifespan."

In the 2020 study, the clearest difference between the groups was not how long the mice lived but how frail they became.

Section 2

Compressed Morbidity, in Plain Words

Gerontologists have a name for this goal: compression of morbidity. The idea, first described decades ago, is that the best outcome is not simply adding years, but squeezing the period of illness and frailty into a shorter stretch at the very end of life.

Many interventions in animals do the opposite. They extend life, but the extra time is spent frail. The title of the 2020 paper claimed something different: AKG "extends lifespan and compresses morbidity in aging mice." The treated animals did not just live a little longer; a larger share of their lives was spent in good condition.

Section 3

Females and Males Did Not Respond Identically

The results were not uniform. Female mice tended to fare better on most frailty measures, while male mice showed their own advantages, such as better preserved muscle and better gait and grip on some measures.

Sex differences like this are common in ageing research, and they are a useful reminder that one average can hide different stories. Any human trial needs to look at men and women separately rather than assume one answer fits both.

Section 4

What a Mouse Study Cannot Tell You

As encouraging as the mouse data are, they leave important questions open for people:

Dose. The mice received AKG mixed into their food for the rest of their lives. Turning a mouse diet into a human daily dose is not a simple calculation, and the study does not tell us what amount would matter for a person.

Conditions. Laboratory mice live in controlled environments with identical food, temperature and routine. Human lives are far more varied.

Outcomes. A mouse frailty index is a well-designed tool, but it is not the same as human strength, fitness or independence. The only way to know whether AKG helps people is to measure people.

This is why the logical next step after a strong mouse result is a well-designed human trial, not a human headline. And as Chapter 1 showed, the first widely shared human result was the headline. The trial came next.

Chapter 4

The Trial Built to Settle It

So we have a molecule your body already makes, a convincing result in old mice, and a famous human number that cannot yet separate AKG from everything else that happens between two blood tests. The way to close that gap is not a bigger headline. It is a fair test.

One is already running. It was designed by researchers who know the earlier data well, and it is built to answer precisely the question the 2021 paper left open.

Section 1

What a Fair Test Looks Like

Each feature of a good clinical trial removes one of the alternative explanations from Chapter 1:

Randomised. A computer, not the participant, decides who gets the real capsule. That removes the problem of motivated people choosing themselves into the treatment group.

Placebo-controlled. Half the participants take an identical-looking capsule with no active ingredient. They experience regression to the mean, test variability and lifestyle changes just as the treated group does, so those effects cancel out in the comparison.

Double-blind. Neither participants nor researchers know who is taking what until the end. That stops expectations from colouring behaviour or measurements.

Pre-registered outcome. The main result to be measured is published before the trial begins, so nobody can pick the most flattering number afterwards.

Section 2

Inside ABLE

The trial is called ABLE, short for Alpha-ketoglutarate supplementation and BiologicaL agE in middle-aged adults, and it is run by the Healthy Longevity programme at the National University of Singapore. Its full design was published in the journal GeroScience in 2023.

ABLE enrolled 120 generally healthy adults aged 40 to 60 whose DNA-methylation age came out higher than their calendar age. Half take 1 g a day of sustained-release calcium AKG and half take a placebo, for six months, followed by three months of follow-up without treatment.

The primary outcome is the change in DNA-methylation age, the same kind of measure behind the eight-year headline. But the trial also measures things you could feel or that clinicians use every day: handgrip and leg strength, aerobic capacity, arterial stiffness, inflammatory and metabolic markers in the blood, and skin autofluorescence, a marker linked to long-term sugar damage in tissues.

A 2025 report on recruitment showed how carefully participants were selected: of 467 people who expressed interest, 120 were enrolled. It also noted that, at enrolment, biological age exceeded calendar age in 80.2% of participants, not all of them, even though screening looked for exactly that. The report does not dwell on it, but it is a quiet illustration of the point from Chapter 1: one reading of the same person does not always agree with the next.

At the time of writing, ABLE's results have not yet been published. When they are, they will be the first placebo-controlled answer to the question this article opened with.

Identical bottles, sealed and unlabelled: in a double-blind trial, nobody knows which one holds the real capsule until the end.

Section 3

Five Questions for Any Biological-Age Claim

Biological-age claims are everywhere now, for supplements, diets, devices and clinics. You do not need a statistics degree to judge them. These five questions cover most of what matters:

Apply these to the 2021 paper and to ABLE side by side, and you can see why researchers treat them so differently, even though they study the same molecule.

When ABLE does report, three details will be worth looking for. First, the size of the difference between the AKG and placebo groups, not just whether it is "significant": a change of a few months reads very differently from a change of several years. Second, whether the secondary outcomes move in the same direction. A lower DNA-methylation age alongside better grip strength or aerobic capacity would be far more persuasive than a clock result on its own. Third, what happens during the three months after treatment stops, which hints at whether any effect lasts.

And if the result is modest, or mixed, that is still valuable. A well-run trial that finds a small effect tells us more than an uncontrolled study that finds a large one, because we can actually trust what it measured.

Section 4

Where This Leaves You

Here is the honest summary. AKG has unusually good animal evidence, in worms and especially in old mice, where it reduced frailty more than it extended life. Human evidence on ageing is early: the most famous number comes from an uncontrolled study, and the placebo-controlled answer is still to come. The Singapore researchers' own 2021 review put it plainly: further clinical studies are needed to understand what AKG does in people.

That leaves two reasonable positions. You can wait for ABLE. Or you can decide that a molecule your body already makes, with a strong animal record, is worth including in your daily routine now, while knowing the human question is still open.

If you are in the second group, the next question is how to take it. Some people want AKG on its own. Others prefer one daily formula that brings AKG together with the NAD+ precursors many of our readers already use. That second approach is what Life ULTRA was built for.

The formula in this article

Life ULTRA

One daily formula (2 capsules) with 400 mg calcium alpha-ketoglutarate alongside the NAD+ family (100 mg β-NMN, 50 mg NMNH, 80 mg NAD+, 20 mg NADH), plus 100 mg CoQ10, 6 mg astaxanthin, 50 mg liposomal apigenin and 15 mg piperine. 60 capsules, a 30-day supply.

Who it suits: adults in midlife and beyond who want AKG and NAD+ precursors in one daily step rather than several separate products.

The AKG amount is below the 1 g a day ABLE is testing. Life ULTRA is a broad daily formula, not a copy of the trial.

Add Life ULTRA to cart · €94.95 →See full details

Or pass the Final Master Quiz below first: 4 out of 5 unlocks a private reader reward on Life ULTRA.

Whatever you decide, keep the five questions handy. When ABLE reports, they are exactly what you will need to read the result well, whichever way it falls.

🎁 ONE STEP LEFT: YOUR READER REWARD

You have read all four chapters. Five questions now stand between you and your reward.

Score at least 4 out of 5 on the Final Master Quiz below and your private reader code unlocks instantly. Valid until 3 November 2026.

Everything you need is in the chapters you have just read.

Complete Reference List

The human headline

What AKG is and does

Ageing mice

The placebo-controlled trial