On this page
Calcium alpha-ketoglutarate (Ca-AKG) is a stable salt of a molecule your own cells make every second of your life. In the past five years, it has become one of the most talked-about longevity supplements on the market, driven by a striking mouse lifespan study and a widely shared observational finding about biological age.
The mouse data is genuinely encouraging. The human data is genuinely thin. This guide walks through what calcium alpha-ketoglutarate actually is, what the peer-reviewed evidence shows in 2026, and what to do with that information if you are deciding whether to take it. Every claim links back to a paper in our Ca-AKG Data Center, where you can read our full evidence assessment of each source.
What is calcium alpha-ketoglutarate?
Alpha-ketoglutarate (AKG) is a small molecule your cells produce constantly. It sits in the middle of the Krebs cycle — the pathway that turns food into energy inside every mitochondrion in your body. It also feeds amino acid production, ammonia detoxification and, through a family of enzymes called dioxygenases, some of the machinery that switches genes on and off.
Calcium alpha-ketoglutarate is that same molecule packaged as a calcium salt. The calcium keeps it stable in a capsule and helps it survive the acidic environment of the stomach. Once absorbed, it splits back into calcium and free AKG.
That is the whole compound. There is no rare extract and no proprietary ingredient. It is a normal metabolite of human biochemistry, delivered in a stable salt form. If you want a slower, easier introduction to the compound before you go further, our explainer on what Ca-AKG is walks through it without any of the technical vocabulary in this pillar.
Is calcium alpha-ketoglutarate the same as calcium?
No. The calcium is a delivery vehicle, not the point.
A typical 1 g dose of Ca-AKG contains roughly 200 mg of elemental calcium — around 15 to 20 per cent of the recommended daily intake for most adults. If you already take a separate calcium supplement, you should factor Ca-AKG's calcium content into your total. If you have a history of kidney stones, you should discuss any added calcium with your doctor before starting.
But the reason people take Ca-AKG for longevity is the alpha-ketoglutarate half. The calcium is the carrier.
What does it actually do in your body?
Three roles stand out mechanistically. For a full mechanistic breakdown, see how Ca-AKG works in the Krebs cycle, epigenetics and cellular ageing.
Energy. AKG is a compulsory step in the Krebs cycle. Every cell in your body cycles it through the mitochondrion to generate ATP.
Epigenetic regulation. AKG is the required cofactor for a family of enzymes called dioxygenases — including TET enzymes, which regulate DNA methylation, and JmjC histone demethylases, which regulate the histone code. Both are pathways that drift with age. Age-related decline in tissue AKG has been proposed as one reason those pathways start misfiring.
Inhibition of ATP synthase and TOR. A 2014 Nature paper showed that AKG binds directly to a subunit of mitochondrial ATP synthase and, downstream, inhibits TOR kinase — the same pathway rapamycin acts on [1]. This is the mechanistic argument for why AKG might mimic caloric restriction. A follow-up study in fruit flies confirmed the same lifespan-extending effect, mediated by AMPK activation on top of TOR inhibition [2].
Downstream of TOR inhibition, one proposed cellular consequence is enhanced autophagy — the cell's process of clearing damaged proteins and organelles. Whether oral Ca-AKG actually increases autophagy in human tissue is a separate question, and the evidence is less settled than the marketing suggests. We cover this fully in Ca-AKG and autophagy: what the evidence actually shows.
A comprehensive 2022 review in Trends in Endocrinology and Metabolism synthesised the mechanistic and preclinical work across ageing, muscle, bone, brain and cardiovascular applications, and concluded that AKG is a plausible candidate for further human study across multiple age-related domains [3].
Whether swallowing an oral Ca-AKG capsule shifts these pathways enough to change how a human ages is a different question — and the one we still cannot fully answer.
What does the peer-reviewed evidence show?
The evidence base falls into five buckets. Each bucket carries different weight.
The preclinical picture — lifespan, blood vessels and brain
The paper the entire modern longevity conversation about Ca-AKG traces back to was published in Cell Metabolism in 2020 by a team at the Buck Institute. Adult C57BL/6 mice fed Ca-AKG in their food from middle age lived longer and — more strikingly — compressed the frail portion of their lives. They spent more time healthy and less time sick before they died [4]. The same paper also reported reduced grey hair in Ca-AKG-fed mice, a specific finding worth understanding in context — we cover it in Ca-AKG and grey hair: what the mouse study actually showed. For a paper-by-paper walkthrough of this study, see our Shahmirzadi 2020 deep-dive.
Beyond lifespan, the preclinical picture extends into specific organ systems. A controlled feeding study in aged mice found that Ca-AKG improved aortic elasticity and reduced markers of oxidative stress in the vascular wall, suggesting a possible role in arterial ageing [5]. And a 2025 Aging Cell paper reported that Ca-AKG rescued synaptic plasticity deficits in the APP/PS1 mouse model of Alzheimer's disease, through mechanisms involving glutamate receptor signalling and autophagy [6].
These are strong mouse studies. They are not human trials. The doses used, corrected for body-surface area, work out to something in the range of typical human supplement doses — but "works out to" is not the same as "has been shown".
The one human randomised trial that has already reported
Only one randomised, double-blind, placebo-controlled human trial of Ca-AKG has been fully published to date. In 2007, a Polish group randomised 76 postmenopausal women with osteopenia to Ca-AKG or placebo for six months. The Ca-AKG group showed a significant reduction in serum CTX — a bone resorption marker [7].
This is a small, single-site, industry-funded trial in a specific population using a bone biomarker rather than fractures or bone density change as the endpoint. It is not evidence that Ca-AKG prevents osteoporotic fractures. It does show that the compound is bioactive at oral doses in humans and can move a bone-turnover marker in the expected direction. For the full evidence walkthrough on the bone question, see Ca-AKG for bone health.
The proprietary Rejuvant retrospective
In 2021, a team associated with Ponce de Leon Health published a retrospective analysis in the journal Aging. They reviewed customers of the company's proprietary product Rejuvant — a delayed-release Ca-AKG formulation combined with vitamins — who had taken the TruAge DNA methylation age test before and after supplementation. Average DNA methylation age dropped by approximately eight years after roughly seven months of use [8].
The headline number travelled far. The methodology deserves a closer read.
This was not a trial. There was no placebo group. Participants self-selected to take the product and to test their DNAm age. The analysis was industry-conducted. And the outcome used a single first-generation methylation clock, which is known to be sensitive to short-term physiological state.
The finding is hypothesis-generating. It is not evidence that Ca-AKG causes a biological age reversal.
The 2026 cross-sectional cohort of 4,260 people
The largest human dataset on Ca-AKG to date was published in Aging Cell in May 2026. Researchers analysed 4,260 exceptionally healthy adults who had done at least one saliva-based DNAm age test between 2020 and 2025. They looked at the association between 84 different supplements and biological age, measured as the residual between DNAm age and chronological age [9].
Delayed-release Ca-AKG — the Rejuvant formulation, again — showed the largest association of any supplement tested. On average, users had a biological age approximately 1.8 years lower than expected, after adjusting for age, sex, smoking status and self-reported health. Standard non-delayed-release Ca-AKG showed an effect roughly eight times smaller and did not reach statistical significance.
This is a stronger dataset than the 2021 retrospective. It is also still a cross-sectional analysis of a self-selected, health-optimising population, and one of the senior authors has a financial interest in the manufacturer of the product that came out on top. Read it as consistent with the earlier signal, not as proof. Our fuller treatment of the biological age story — how the Rejuvant retrospective, the 2026 cohort, and the ABLE trial fit together — lives in Ca-AKG and biological age.
The trials we're waiting for
Two randomised, double-blind, placebo-controlled trials of Ca-AKG in humans are in the field right now.
The ABLE trial, coordinated out of Singapore, is testing Ca-AKG against placebo in middle-aged adults with biological age as the primary endpoint. The full protocol was published in 2023 [10].
A second trial, sponsored by Shenzhen Hygieia Biotech and run at Zhejiang Chinese Medical University, is testing Ca-AKG against a starch placebo in 30 middle-aged and older adults for 12 weeks, with PhenoAge as the primary endpoint. The trial is registered as NCT07114536, enrolment closed in late 2025, and the primary completion date is January 2026 — so results are imminent [11].
Between them, these two trials will move the human evidence base for Ca-AKG substantially over the next 12 to 18 months. Everything published to date is a preface.
Does calcium alpha-ketoglutarate reverse ageing?
Not in the sense the marketing implies.
The molecule is genuinely involved in pathways that decline with age. In mice, supplementing it makes the animals live longer and healthier [4]. In two observational human datasets using the delayed-release proprietary form, users showed lower biological age on a methylation clock than expected — but neither dataset can tell us Ca-AKG caused the difference [8] [9].
A biological age clock measurement is not the same as a clinical outcome. Nobody has shown that oral Ca-AKG lowers your cardiovascular risk, extends your lifespan, reduces your risk of any age-related disease, or reverses any tissue-level marker of ageing beyond a composite score derived from DNA methylation patterns.
Consistent signal. Encouraging biology. Unproven clinical benefit. That is where the honest reading of the evidence sits in 2026.
What form and dose does the research actually use?
The doses matter, because supplement labels do not always match trial doses.
The Cell Metabolism mouse study used food-incorporated Ca-AKG at a level that, corrected for surface area, corresponds to roughly 1 g per day in a human adult [4]. The 2021 Rejuvant retrospective used the proprietary Rejuvant capsule, which delivers 1,000 mg of delayed-release Ca-AKG per day [8]. The ABLE trial protocol tests 1,000 mg per day [10]. The Chinese trial protocol lists 1 to 2 g per day depending on the source document, and the true administered dose is currently being clarified with the sponsor [11].
A rough consensus of 1 g per day emerges — but with two important caveats.
First, the delayed-release formulation used in the human observational data is proprietary. Whether a standard immediate-release Ca-AKG capsule at the same dose produces the same biological effect is genuinely unknown. The 2026 cohort study is the strongest data point we have on that question, and it found the standard form's effect to be roughly eight times smaller and non-significant [9].
Second, Ca-AKG is one of several widely sold AKG forms. The other common ones — arginine alpha-ketoglutarate (AAKG, marketed for exercise performance) and plain AKG — are not interchangeable with Ca-AKG. The longevity data uses Ca-AKG specifically. Two comparison guides walk through the important disambiguations: Ca-AKG vs AAKG and Ca-AKG vs plain AKG. The full picture across every form on the market, including ornithine AKG, sodium AKG and creatine-AKG, sits in AKG forms explained.
For the practical questions the research corpus does and does not answer on dose sizing, split dosing and duration, see Ca-AKG dosage: what the trial data supports. For the empty-stomach-vs-with-food and morning-vs-evening questions, see when to take Ca-AKG. If you take other longevity supplements and want to know how Ca-AKG fits alongside them, Ca-AKG stacking covers pairings with NMN, fisetin, and other common stack members.
Is it safe?
Calcium alpha-ketoglutarate and its close relatives have been used in clinical medicine for decades. Ornithine alpha-ketoglutarate is a mainstream post-surgical and burn-recovery agent. Ca-AKG itself has been given to malnourished dialysis patients, tested in postmenopausal women with osteopenia, and used as a nitrogen-scavenging aid in various clinical contexts. A 2017 review in Archivum Immunologiae et Therapiae Experimentalis catalogues this history in detail [13]. The 2007 osteopenia trial reported no significant adverse events over six months [7].
The published longevity-context human studies have also reported no significant adverse events, though the sample sizes are small [8] [10].
Three practical caveats.
Calcium load. Around 200 mg of elemental calcium per 1 g of Ca-AKG counts towards your total daily calcium intake. Someone already taking a calcium supplement, plus a fortified diet, plus 2 g of Ca-AKG can readily exceed the tolerable upper intake for calcium. If you have a history of kidney stones, factor this in.
Untested populations and interactions. Ca-AKG has not been formally tested in pregnancy or during breastfeeding. It has not been tested for drug interactions in any systematic way. If you are on chemotherapy, take medications with narrow therapeutic windows (warfarin, lithium, certain anti-epileptics), or have significant kidney disease, the responsible answer is to speak to your doctor before starting.
Supplement-grade regulation. Ca-AKG is regulated as a food supplement, not a medicine. Batch-to-batch potency and purity depend entirely on manufacturer quality control. Choose products that publish third-party assays.
For a fuller treatment of the safety profile, contraindications and reported adverse effects across the published human literature, see Ca-AKG side effects and safety profile. The specific cancer question — the one people ask most often about longevity supplements that affect cell growth pathways — is covered separately in Ca-AKG and cancer: the honest evidence check.
What about other proposed benefits?
Beyond the biological age headline, three benefit areas come up regularly in reader questions. Each has its own evidence article in this cluster because the answers are more nuanced than a pillar can honestly summarise.
Muscle and frailty. A 2024 narrative review in Nutrients synthesised more than a hundred papers on AKG in skeletal muscle regeneration, atrophy and exercise performance across preclinical models and small human trials [12]. The signal is consistent enough to warrant its own evidence review — see Ca-AKG for muscle, frailty and sarcopenia.
Inflammation. One of the proposed mechanisms by which Ca-AKG might affect biological age is by reducing the senescence-associated secretory phenotype (SASP) — the low-grade inflammatory output of senescent cells that drives inflammaging. The evidence is still preclinical and early — Ca-AKG and inflammation walks through what the SASP, cytokine, and inflammaging literature actually shows.
Weight and metabolic health. Ca-AKG has been proposed to influence insulin sensitivity and fatty liver via its effects on the Krebs cycle and hepatic metabolism. The direct human evidence is thin. For the honest metabolic and weight-loss picture, see Ca-AKG for weight loss and fatty liver.
Where does it come from in food?
Almost no Ca-AKG comes from food directly. AKG is an intracellular metabolite — you produce it inside your own cells, not consume it from your diet.
The precursor amino acids that feed into AKG production — glutamine and glutamate — are abundant in meat, fish, eggs, dairy, and to a lesser extent legumes. Whether increasing dietary intake of these precursors meaningfully raises intracellular AKG in humans is unclear.
Exercise, on the other hand, reliably raises intracellular AKG in muscle tissue. The literature is consistent enough on this that muscle-physiology reviews list exercise as the most reliable non-supplement route to elevated AKG [12].
For someone whose goal is Krebs-cycle support without a capsule: adequate protein, sufficient calories, and regular resistance and aerobic training will do more to keep AKG production healthy than any dietary strategy alone. The full food breakdown, including which foods contain AKG precursors and how endogenous production works, lives in Ca-AKG dietary sources.
How does Ca-AKG compare with other longevity supplements?
Ca-AKG is one of several supplements marketed under the broad "longevity" banner. Each acts on different pathways, has different evidence maturity, and suits different reader questions. We compare them directly in dedicated guides: Ca-AKG vs NMN (a different pathway — NAD+ precursor vs Krebs cycle intermediate), Ca-AKG vs Urolithin A (mitochondrial biology compared), and pairing Ca-AKG with fisetin (Krebs-cycle metabolite alongside a senolytic). None of these is a like-for-like substitute for Ca-AKG. Each answers a different question.
How to choose a Ca-AKG supplement
The market ranges from proprietary delayed-release capsules (Rejuvant, priced accordingly) to generic immediate-release Ca-AKG powder. Given the 2026 cohort data showing a substantial gap between the two forms, the "which product" question is not trivial. Our full comparison of the products currently on the UK and US market, with a physician-authored assessment of what to look for on the label and what to ignore, lives in Best Ca-AKG supplement in 2026: how to choose and what to look for.
What we still don't know
Several substantial gaps remain — and they matter for how confidently anyone can recommend the compound.
Whether standard immediate-release Ca-AKG produces any meaningful biological effect at typical doses. The 2026 cohort data suggest it does not — or does so at a much smaller magnitude than the delayed-release proprietary form [9].
Whether the DNAm age reductions reported in the human observational data translate to any clinical outcome. Nobody has shown reduced disease incidence, reduced cardiovascular events, or reduced all-cause mortality with Ca-AKG.
Whether the effect requires continuous use to persist. Both the Rejuvant retrospective and the 2026 cohort measured people who were still taking the product. What happens to biological age when someone stops supplementing has not been studied.
Whether Ca-AKG behaves differently — or at all — in already-healthy young adults compared to middle-aged and older adults with subclinical mitochondrial decline. The mouse work was in aged mice. The human observational data was in a health-optimising, mostly middle-aged and older population.
The ABLE trial and the Chinese trial will address the first, second and third of these questions in part. They will not answer all of them.
Bottom line
Calcium alpha-ketoglutarate is a real molecule with a real role in human biochemistry. There is a real signal that supplementing it in middle-aged and older adults may modestly lower biological age as measured by DNA methylation clocks. That signal is strongest for the delayed-release proprietary form (Rejuvant) and much weaker or absent for the standard immediate-release form most non-proprietary capsules provide.
The mouse lifespan data is encouraging. The human data is early, mostly observational, and does not yet demonstrate any clinical outcome. Two randomised placebo-controlled trials will report in the next 12 to 18 months and will move this conversation substantially.
If you are considering Ca-AKG as a longevity supplement in 2026, the honest position is this: the biology is plausible, the observational human signal is real but modest, safety looks acceptable at typical doses, and clinical proof is not yet in. Take it if you are comfortable acting on Tier 2 and Tier 3 evidence. Wait if you would rather see the trials read out first.