Calcium alpha-ketoglutarate (Ca-AKG)
Summary
Ca-AKG extended lifespan in female mice and reduced frailty in both sexes in a 2020 study whose authors held shares in a supplement company. In people, the only aging data come from an uncontrolled, company-linked analysis of 42 product users (grade D). A 120-person placebo-controlled trial (ABLE) had not published outcomes as of October 2026.
Key facts
- The calcium salt of alpha-ketoglutarate (AKG), an intermediate of the Krebs cycle[1]
- About 190 mg of calcium per 1,000 mg of Ca-AKG monohydrate (from a product label reported in the Rejuvant study)[2]
- One retrospective analysis of 42 users, with no control group, by authors linked to the product maker[2]
- ABLE: 120 adults aged 40–60, 1 g sustained-release Ca-AKG vs placebo for 6 months; protocol, recruitment and feasibility papers only, no outcome results published as of October 2026[3][4][8]
- 4 graded human outcomes on this page
- October 12, 2026
How it works
ProposedIn mice, dietary Ca-AKG lowered inflammatory cytokines and raised IL-10, which the authors propose as the route to longer healthspan. The ABLE trial is testing whether it lowers DNA methylation age in people; no controlled human result has been published yet.[1][3]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
At a glance: strongest evidence per outcome
| Outcome | Grade | Effect | Strongest evidence | Rows |
|---|---|---|---|---|
| Biological age | Grade D | Worsened | Observational · n = 42 · 2021 | 1 row |
| Kidney disease (phosphate) | Grade D | Worsened | Crossover RCT · n = 28 · 1999 | 3 rows |
Every graded row
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Epigenetic (DNA methylation) age in product users | Worsened | Grade D | Observational · n = 42 · 2021 Self-reported healthy customers of a commercial supplement who had two methylation tests (USA) Form: Rejuvant: sustained-release Ca-AKG with vitamin A (men) or vitamin D (women) · Dose: 1 g Ca-AKG per dose · Duration: 4–10 months (average 7) Average biological age on a commercial saliva methylation test was about 8 years lower at follow-up than at baseline (p=6.5×10⁻¹²). There was no control or placebo group, and duration of use did not correlate with the size of the change. | 34847066 (opens PubMed)Source [2] |
| Serum phosphate and calcium in hemodialysis (Ca-AKG as a phosphate binder) | Worsened | Grade D | Crossover RCT · n = 28 · 1999 Adults on maintenance hemodialysis Form: Calcium ketoglutarate vs calcium acetate · Dose: Matched to calcium acetate by elemental calcium · Duration: 12 weeks per arm Both binders lowered phosphate to a similar plateau; high blood calcium (≥2.8 mmol/L) occurred in 1 patient on Ca-AKG vs 8 on calcium acetate (P=0.03). PTH did not differ. | 10383011 (opens PubMed)Source [5] |
| Phosphate control and tolerability vs calcium carbonate in hemodialysis | Mixed | Grade D | Crossover RCT · n = 19 · 1998 Adults on chronic hemodialysis (Denmark) Form: Calcium ketoglutarate granulate vs calcium carbonate · Dose: Not stated in the abstract · Duration: 12 weeks per arm Ionized calcium was lower on Ca-AKG; phosphate and PTH did not differ significantly. Five of 17 patients stopped Ca-AKG within 1–2 weeks because of anorexia, vomiting, diarrhea or general unease; only 10 completed both arms. | 9469496 (opens PubMed)Source [6] |
| Parathyroid hormone during long-term Ca-AKG in hemodialysis | Worsened | Grade D | Open-label trial · n = 14 · 1996 Adults on hemodialysis Form: Soluble calcium alpha-ketoglutarate · Dose: About 4.5 g/day (0.975 g elemental calcium) · Duration: 36 months Serum phosphate fell, serum calcium rose (2.2 to 2.47 mmol/L) and intact PTH normalized in all patients. | 8676818 (opens PubMed)Source [7] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Sustained-release calcium alpha-ketoglutarate | 19%[2] | No published human absorption study of oral Ca-AKG supplements was found.[2][3] | Planned 1 g in the ABLE trial; tolerability results not yet published.[3][4] | Biological-age study (uncontrolled) and the ABLE trial (results pending) |
| Calcium ketoglutarate as a phosphate binder | Varies[7] | Acts in the gut by binding dietary phosphate.[5][7] | 5 of 17 dialysis patients stopped within 2 weeks because of stomach and bowel symptoms; high blood calcium was less frequent than with calcium acetate.[6][5] | Phosphate control in hemodialysis |
Compound weight → elemental active
500 mg sustained-release calcium alpha-ketoglutarate ≈ 95 mg elemental active
Studied doses
Doses studied in human trials ranged from 1 g of sustained-release Ca-AKG (an uncontrolled product study over 4–10 months, and the ABLE trial, still unreported) to about 4.5 g/day used as a phosphate binder in hemodialysis for up to 36 months.[2][3][7]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
None found in our sources.
Who should be careful
- Kidney disease or dialysis
- Ca-AKG binds phosphate and raised blood calcium in dialysis patients at about 4.5 g/day; in that setting it is a supervised medical treatment.[5][7]
- Existing stomach or bowel problems
- In a dialysis trial, 5 of 17 patients stopped Ca-AKG within 2 weeks because of anorexia, vomiting or diarrhea; all had prior digestive symptoms.[6]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
How to read the label
- Ca-AKG vs AKGDoses are usually stated as Ca-AKG (the salt). About 19% of a Ca-AKG monohydrate dose is calcium, which counts toward total calcium intake.[2]
- Combination productsThe human biological-age study used a product that also contained vitamin A (men) or vitamin D (women), so the effect of Ca-AKG alone cannot be separated.[2]
- Other AKG saltsArginine AKG and ornithine AKG are different compounds; the studies here used the calcium salt.[1][2]
Cost per studied dose, without the sales pitch
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Cost per studied dose
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Where to buy Calcium alpha-ketoglutarate (Ca-AKG)
Products from brands we partner with that contain Calcium alpha-ketoglutarate (Ca-AKG). Listing a product is not a claim that it works; check the amount per serving against the doses studied above, and the label for other ingredients.
- SupersmartPaid linkCalcium AKG2 capsules: 1,000 mg calcium alpha-ketoglutarate; 30 servings. Matches the 1 g dose in the ABLE trial, which has not reported results; adds roughly 190 mg calcium.Shop at Supersmart (opens in new tab)Price and label checked 2026-10-11 on the brand’s site.
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Frequently asked questions
Does Ca-AKG lower biological age?
Not shown in a controlled trial. An uncontrolled study of 42 product users reported an 8-year drop on a saliva methylation test, but it had no placebo group and was linked to the product maker.[2]
Has Ca-AKG been tested against placebo for aging?
The ABLE trial (120 adults, 1 g for 6 months) is the first; its outcome results had not been published as of October 2026.[3][4][8]
Did Ca-AKG extend lifespan in animals?
Yes, in female mice started at 18 months of age, with reduced frailty in both sexes, in a study whose authors held shares in a supplement company.[1]
How much calcium is in Ca-AKG?
About 190 mg of calcium per 1,000 mg of Ca-AKG monohydrate.[2]
Sources
- [1]Alpha-Ketoglutarate, an Endogenous Metabolite, Extends Lifespan and Compresses Morbidity in Aging Mice.. Cell Metab, 2020. animal-study
- [2]Rejuvant®, a potential life-extending compound formulation with alpha-ketoglutarate and vitamins, conferred an average 8 year reduction in biological aging, after an average of 7 months of use, in the TruAge DNA methylation test.. Aging (Albany NY), 2021. observational
- [3]Alpha-ketoglutarate supplementation and BiologicaL agE in middle-aged adults (ABLE)-intervention study protocol.. Geroscience, 2023. RCT
- [4]Recruitment evaluation of a gerotherapeutic randomized controlled trial testing alpha-ketoglutarate in biologically older, middle-aged adults (ABLE).. Exp Gerontol, 2025. RCT
- [5]Calcium ketoglutarate versus calcium acetate for treatment of hyperphosphataemia in patients on maintenance haemodialysis: a cross-over study.. Nephrol Dial Transplant, 1999. crossover-RCT
- [6]Randomized crossover study comparing the phosphate-binding efficacy of calcium ketoglutarate versus calcium carbonate in patients on chronic hemodialysis.. Am J Kidney Dis, 1998. crossover-RCT
- [7]Long-term treatment with calcium-alpha-ketoglutarate corrects secondary hyperparathyroidism.. Miner Electrolyte Metab, 1996. open-label
- [8]Optimizing accelerometer implementation in a gerotherapeutic trial: Feasibility, adherence, and operational insights of ABLE.. PLOS Digit Health, 2026. RCT
What changed
- First draft. Every PMID checked against NCBI E-utilities esummary (title and year taken from the record) and abstracts read for the cited rows.
- Adversarial review pass: every evidence row re-read against its PubMed abstract; Rejuvant composition, calcium content and conflicts of interest checked in PMC8660611; mouse funding, shareholdings and the calcium-free control diet checked in PMC8508957. PubMed searched for ABLE outcome papers: only protocol (2023), recruitment (2025) and accelerometer-feasibility (2026) papers found. Dialysis phosphate-binder studies labeled as medical use. Retraction, expression-of-concern, erratum and withdrawn checks on all 8 PMIDs: none flagged.
- Independent adversarial review (PR #201): spot-checked Rejuvant, ABLE and dialysis rows against PubMed abstracts and the female-only lifespan result against the Cell Metabolism paper. Summary trimmed to under 60 words; mouse-study conflict of interest restated as disclosed (author shareholdings, board seat, patent application) rather than as company funding.