A pharmacokinetic study and critical reappraisal of curcumin formulations enhancing bioavailability

Kroon MAGM, van Laarhoven HWM, Swart EL, van Tellingen O, Kemper EM · iScience

Tests C3 Complex with black pepper directly, and independently. Unconjugated curcumin was below the 2 nM limit of quantitation in every participant on C3 Complex at 600 mg, at 2400 mg, at 2400 mg with piperine, and on Longvida; only NovaSOL gave measurable free curcumin (median Cmax 14.9 nM, range 6.7-38.4), still about 100-fold under in-vitro active concentrations, and back to 1.2 nM by 4 hours. Median total-curcumin AUC was 289 nM·h for C3 600 mg, 897 for C3 2400 mg, 524 for C3 2400 mg plus piperine — lower than the same dose without it — 271 for Longvida and 11,590 for NovaSOL. The authors' verdict on the additive is that it 'is useless'.

Population

Healthy male volunteers, five-way crossover, Amsterdam UMC

Intervention

Curcumin C3 Complex 600 mg, C3 Complex 2400 mg, C3 Complex 2400 mg with piperine 20 mg, NovaSOL polysorbate-80 micelles 576 mg curcuminoids, and Longvida solid lipid particles 625 mg curcuminoids

Comparator

Within-subject comparison across the five products

Limitations

Nine healthy men (seven completed all five products), single doses, wide inter-individual ranges and no clinical endpoint; the piperine comparison is within a crossover rather than a powered non-inferiority test, and the capsules' measured curcuminoid content fell 13 to 33% short of label. Independent (Amsterdam UMC / NKI, funded by an internal pharmacy grant, no competing interests), which is unusual in this literature; the authors' point is that bioavailability claims are routinely computed on conjugates that cannot cross membranes.