Ca-AKG

Supplement grade is the dominant specification, assaying 98 percent or higher on a dried basis, with the calcium content controlled in parallel because the hydration state shifts it. Both monohydrate and anhydrous forms are traded, and the certificate should state which, since the assay basis and the declared calcium contribution differ between them.

Particle size is the main variable beyond assay. A fine milled powder is used for capsule filling and stick packs, while a granulated or agglomerated grade with improved flow and lower dust is preferred for direct compression tablets. A pharmaceutical grade with tighter heavy metal and residual solvent limits exists for registered preparations, and coated or microencapsulated versions are made where the acidity of the salt would otherwise interfere with other actives in a blend.

In the United States, calcium alpha-ketoglutarate is marketed as a dietary ingredient under the Dietary Supplement Health and Education Act rather than as an approved food additive, and finished products are therefore positioned as supplements rather than conventional foods. Calcium salts of organic acids are long established as nutrient sources in supplement form, and the calcium contribution is declared on the supplement facts panel.

In the European Union, alpha-ketoglutarate salts are not authorised as food additives and carry no E number. Their use in food supplements depends on the national rules of the member state and on novel food status, since a substance without a significant history of consumption in the Union before May 1997 requires authorisation under the novel food regulation before it can be placed on the market. Calcium itself is an authorised nutrient for supplement use, but the permitted source list governs which salts may supply it. There is no JECFA additive specification for the calcium salt, so buyers rely on the manufacturer's monograph and analytical dossier.