Formulation-dependent dissolution and bioaccessibility of curcuminoids and (S)-ar-turmerone from eight commercial...

Curcumin-containing dietary supplements are widely marketed with claims of enhanced bioavailability, despite well-recognized limitations related to poor aqueous solubility, chemical instability, and extensive first-pass metabolism. Comparisons among commercially available products using physiologically relevant performance metrics remain limited.

To systematically evaluate disintegration, dissolution, and bioaccessibility of curcuminoids and (S)-ar-turmerone from a cross section of commercially available turmeric dietary supplements under fasted- and fed-state biorelevant conditions.

Eight marketed turmeric supplements representing diverse formulation strategies were assessed for disintegration and dissolution using USP-aligned methods in fasted- and fed-state simulated gastric and intestinal media (FaSSGF, FaSSIF, FeSSGF, FeSSIF). Bioaccessible concentrations, quantities, and dose fractions of curcuminoids and (S)-ar-turmerone were quantified after 3 h.

All products exhibited poor dissolution overall, with no formulation achieving greater than 40% total release. Dissolution was lowest under fasted-state conditions and improved modestly in fed-state gastric media, reflecting the influence of lipid content. Products with higher curcuminoid loads per capsule generated greater absolute bioaccessible concentrations despite poor release efficiency, whereas a phytosome formulation achieved superior release despite a lower dose. Several products marketed as "enhanced" formulations demonstrated poor disintegration and low bioaccessibility.

These findings indicate that bioaccessible concentration is governed jointly by dosage-form performance and curcuminoid dose loading, and that plasma exposure metrics dominated by conjugated metabolites may not reliably reflect formulation performance.

Commercial turmeric supplements exhibit substantial limitations in biorelevant disintegration and dissolution. Superior in vitro release is a prerequisite - but not a guarantee - for enhanced systemic exposure, underscoring the need for cautious interpretation of bioavailability claims.