Calcium Alpha-Ketoglutarate (Ca-AKG): TCA Cycle Intermediate for Longevity, Muscle Preservation & Bone Health
⚡ 60-Second Summary
Calcium alpha-ketoglutarate (Ca-AKG) is the calcium salt of alpha-ketoglutarate (AKG), a key intermediate in the Krebs (TCA) cycle and a cofactor for alpha-ketoglutarate-dependent dioxygenases — a large enzyme family including TET enzymes (DNA demethylases), prolyl hydroxylases (collagen synthesis), and histone demethylases. AKG levels decline with aging, which correlates with reduced TET enzyme activity and DNA methylation changes associated with aging.
Best-evidenced mechanisms: TET enzyme activation (DNA demethylation correcting aging-associated methylation drift), mTOR pathway modulation (AKG inhibits ATP synthase which modulates mTOR signaling), collagen and connective tissue support (prolyl hydroxylase cofactor essential for collagen synthesis), and nitrogen scavenging (reduces ammonia accumulation in muscle metabolism).
Ca-AKG has extremely limited human clinical evidence — essentially one notable human study and extensive animal data. The longevity rationale is mechanistically compelling (multiple longevity pathways) but translational evidence in humans is in its earliest stages.
What is Calcium Alpha-Ketoglutarate (Ca-AKG)?
Alpha-ketoglutarate has been used medically for decades in critical care (reducing nitrogen catabolism in burns and surgeries). The longevity application emerged from Peng Ying's 2020 Science paper showing AKG extends lifespan in female C. elegans by 50% and other animal models. David Sinclair's lab and others have identified AKG as a key longevity metabolite declining with age.
The most-cited human study is a 2021 study by Demidenko et al. in Aging showing Ca-AKG reversed DNA methylation clock age (biological age) by approximately 8 years in subjects taking the supplement for 7 months.
Evidence-based benefits
Biological Age Reversal (DNA Methylation)
A 2021 open-label study (Demidenko et al., Aging) of 42 adults taking Ca-AKG 1 g/day for 7 months showed an average biological age reduction of 8 years based on DNA methylation clocks, alongside physical improvements in gait speed, grip strength, and wellbeing. This is a single, unblinded study without placebo control — compelling but requires replicated RCT confirmation.
Lifespan Extension in Animal Models
AKG extends lifespan in C. elegans (50% extension), Drosophila, and mice, with reductions in aging-associated markers. These findings motivate human longevity research but are not directly applicable to humans.
Collagen and Connective Tissue
As a prolyl hydroxylase cofactor, AKG is essential for collagen synthesis. Clinical use in surgical recovery (burns, post-op) demonstrates AKG's role in wound healing and tissue regeneration. Supplement amounts may support collagen production.
Muscle Preservation
AKG's nitrogen scavenging properties reduce ammonia accumulation from muscle catabolism. Medical use of AKG in enteral nutrition for muscle-preserving effects in critically ill patients suggests possible relevance for age-related muscle loss (sarcopenia), though direct longevity supplement trials for sarcopenia are lacking.
Supplement forms compared
| Form | Typical dose / Bioavailability | Best for | Notes |
|---|---|---|---|
| Form | Dose | Best For | Notes |
| Calcium AKG Capsules | 1–2 g/day | Longevity, biological age, and collagen support — standard supplement dose | The calcium salt improves stability and palatability vs. AKG acid |
| AKG Powder | 1–2 g/day | Flexible dosing | Acidic taste; calcium salt form preferred for palatability |
| Medical AKG (parenteral) | Much higher doses (IV in clinical settings) | Medical nutritional support — not comparable to oral supplement use | IV AKG in burns/surgery is not equivalent to oral supplement |
How much should you take?
- 1 g/day Ca-AKG — the dose used in the Demidenko 2021 human study
- Take in the morning or with meals — no specific timing evidence for longevity applications
- Long-term consistent use (months) likely required for epigenetic effects
- Evidence base is very early; temper expectations with the limitation of one unblinded human study
Ca-AKG products should specify calcium AKG (not just AKG powder, which has worse palatability and stability). Verify calcium content and AKG content per serving. Few manufacturers have third-party verification for this emerging supplement.
Safety and side effects
Common side effects
- Generally well-tolerated in existing studies
- GI discomfort at higher doses (AKG is acidic — calcium salt form is better tolerated than free acid)
- Calcium contribution is modest at 1 g/day Ca-AKG
- No significant adverse effects established at supplement doses
Serious risks
Ca-AKG appears safe at supplement doses based on limited human data and medical use of higher AKG doses in clinical nutrition. Long-term safety data beyond 7 months is not established.
Drug and nutrient interactions
- Calcium-containing medications and supplements — add to total daily calcium intake calculation
- mTOR-activating medications — AKG modulates mTOR signaling; theoretical interaction
- No significant established drug interactions at supplement doses
Check our free interaction checker for additional combinations.
Who might benefit — and who should use caution
| Most likely to benefit | Use with caution or seek guidance |
|---|---|
| Longevity-focused individuals (particularly 40+) interested in early-access compounds with compelling mechanistic and animal data | Those expecting strong RCT evidence — Ca-AKG has essentially one notable human study; evidence is very preliminary |
| People interested in biological age reversal and DNA methylation clock optimization | People with calcium-sensitive conditions (hypercalcemia, kidney stones) — adds to calcium intake |
| Those willing to experiment with emerging longevity compounds and contribute to n=1 data | Pregnant or breastfeeding women — insufficient safety data |
| Supplement-savvy individuals interested in TCA cycle metabolite optimization alongside NMN and spermidine |
Frequently asked questions
What is alpha-ketoglutarate and why does it decline with aging?
AKG is a key intermediate in the Krebs cycle (the cellular energy-production pathway) and a cofactor for over 60 alpha-KG-dependent dioxygenase enzymes. These enzymes include TET enzymes (which demethylate DNA, reversing aging-associated DNA methylation changes) and prolyl hydroxylases (required for collagen synthesis). AKG levels in blood decline steadily with age — by approximately 50% between ages 30 and 70. This decline correlates with decreased TET enzyme activity and the characteristic DNA methylation drift seen in aging.
What is a DNA methylation clock and what did the Demidenko study show?
DNA methylation clocks (Horvath clock, GrimAge, PhilosoAge) are algorithms that calculate 'biological age' from DNA methylation patterns at specific CpG sites. They predict biological age more accurately than chronological age for many health outcomes. The Demidenko 2021 study showed Ca-AKG supplementation for 7 months reduced biological age by an average of 8 years per GrimAge clock measurements — a striking finding, but from an open-label study (no placebo, no blinding). RCT confirmation is essential.
How does Ca-AKG differ from NMN and resveratrol in longevity stacks?
Different mechanisms targeting different aspects of cellular aging. NMN replenishes NAD+ for sirtuin/PARP activity. Resveratrol activates SIRT1 sirtuins. Ca-AKG works through TET enzyme activation (epigenetic reprogramming), mTOR modulation, and collagen synthesis support. Theoretically complementary as they target distinct longevity pathways. However, Ca-AKG has far less human evidence than NMN or resveratrol.
Is Ca-AKG the same as regular calcium supplements?
No — Ca-AKG is a compound where calcium is bound to alpha-ketoglutarate. The AKG component is the biologically active moiety for longevity applications; the calcium is a delivery vehicle and contributes to daily calcium intake. It should not be considered equivalent to calcium carbonate or calcium citrate supplements for bone health purposes, though it does provide some calcium.
Related ingredients
NMN
Complementary NAD+ longevity supplement targeting sirtuin pathways.
Spermidine
Complementary autophagy-activating longevity supplement.
Urolithin A
Mitophagy-activating longevity compound with stronger human trial evidence.
Disclaimer: This information is for educational purposes only and should not replace medical advice. Always consult a qualified healthcare provider before starting any supplement, especially if you have a medical condition, are pregnant, or take prescription medications. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.