Short answer: Ca-AKG and AKG deliver the same alpha-ketoglutarate anion, but they are not interchangeable on a bench sheet. Ca-AKG is the calcium salt: a more neutral, generally free-flowing powder that carries elemental calcium onto your label and suits capsules, tablets and dry blends. AKG as the free acid is more soluble and strongly acidic, which fits liquid and effervescent systems but raises handling, pH and taste-masking questions. Choose on assay basis, format fit and documentation — not on health-outcome claims.
Ca-AKG vs AKG at a glance
| Property | Ca-AKG (calcium alpha-ketoglutarate) | AKG (free acid) |
|---|---|---|
| Identity | Calcium alpha-ketoglutarate — the calcium salt of alpha-ketoglutaric acid | Alpha-ketoglutaric acid (2-oxoglutaric acid), the free acid form |
| Assay basis | May be declared as the salt or as alpha-ketoglutarate equivalent; the two figures differ because of the counter-ion weight | Assays directly as alpha-ketoglutaric acid, so label math is one step simpler |
| Mineral contribution | Contributes elemental calcium, which must be carried into the nutrition/supplement facts panel | No mineral contribution |
| Behaviour in solution | Closer to neutral; less likely to drive down the pH of a finished system | Strongly acidic in solution; usually needs buffering in neutral systems |
| Handling & flow | Typically a free-flowing powder; generally easier to blend, encapsulate and tablet | Tends to be more hygroscopic and can cake or stick during handling and storage |
| Water solubility | Lower than the free acid; better suited to capsules, tablets and dry blends | More readily water-soluble; suited to liquid and effervescent systems |
| Taste / sensory | More neutral; lighter taste-masking load | Markedly sour and acidic; higher taste-masking load in flavoured formats |
| Format fit | Capsules, tablets, stick packs and dry longevity-positioned blends | Effervescent tablets, acidic RTD and drink systems, or where acidity is wanted |
| Documentation | COA, specification, identity and assay, calcium content, heavy metals, residual solvents, micro, allergen/GMO, stability | COA, specification, identity and assay, heavy metals, residual solvents, micro, allergen/GMO, stability |
| Best when | You need a stable, easy-to-handle dry powder and can accommodate the calcium on the label | You need high solubility in a liquid format and the acidity is acceptable or buffered |
Choose Ca-AKG if…
- Your format is a capsule, tablet, sachet or dry blend and you want a powder that flows and blends predictably.
- You want to avoid pulling the pH of a finished system down, or you are working alongside pH-sensitive actives.
- You can accommodate the elemental calcium contribution in your supplement facts panel and label math.
- Sensory load matters and you would rather not budget for heavy acid-masking.
Choose free-acid AKG if…
- Your format is a liquid, RTD or effervescent system where high water solubility is the deciding property.
- The acidic profile is acceptable, wanted, or already buffered elsewhere in the formula.
- You want the simplest possible assay basis, with no counter-ion weight to reconcile on the label.
- You do not want any additional mineral appearing on the panel.
Documentation & how to verify
Whichever form you shortlist, ask for the same file set before you sample: a current COA, a specification sheet stating the assay basis, identity and assay method, heavy metals, residual solvents, microbiological limits, allergen and GMO statements, and stability information. For Ca-AKG, confirm the stated calcium content and whether the assay is reported as the salt or as alpha-ketoglutarate equivalent — this is the single most common source of label-math disagreement between a buyer and a supplier.
Our manufacturing and testing background is summarised on the quality & certifications page. Ca-AKG sits in our longevity and cellular-aging ingredient range; if you are also evaluating other forms in that category, see urolithin A vs pomegranate extract and NMN vs NR. A broader map of these decisions is in the ingredient selection guides.
Frequently asked questions
What is the difference between Ca-AKG and AKG?
Ca-AKG is calcium alpha-ketoglutarate, the calcium salt of alpha-ketoglutaric acid. AKG usually refers to the free acid (2-oxoglutaric acid). The molecule of interest is the same alpha-ketoglutarate anion; the salt versus free-acid form changes assay basis, calcium contribution, acidity in solution, handling and format fit.
Is Ca-AKG better than AKG?
Neither form is better in the abstract. The calcium salt is usually easier to handle in dry formats and is closer to neutral in solution; the free acid is more soluble and strongly acidic, which suits some liquid or effervescent systems. Choose on your format, label math and documentation needs, not on health-outcome claims.
How should the assay be stated on a Ca-AKG label?
State the basis explicitly. Ca-AKG can be declared as the salt or as alpha-ketoglutarate equivalent, and the two numbers differ because the calcium counter-ion adds weight. Ask for the assay basis on the specification sheet so your label math and your COA agree.
What documentation do you provide for Ca-AKG and AKG?
For both forms we provide a COA, a specification sheet, identity and assay, heavy metals, residual solvent and microbiological data, allergen and GMO statements, and stability information. Ca-AKG specifications also state the calcium content. Request the current file set for review before sampling.
Can I request samples of Ca-AKG and AKG to compare?
Yes. You can request samples, a COA and a specification for both forms so your team can evaluate solubility, handling, taste and documentation side by side before committing to one form.
Request a sample, COA or specification for Ca-AKG or AKG → Contact our team and tell us your format and target use level, and we will send the current documentation for review.