Science of bio available curcumin
Turmeric has a long history of traditional medicinal use in India to address many conditions. Modern cellular studies on curcumin have validated most of its traditional uses and the potential to address natural life conditions typical in Western.(2) Indeed, with almost 4000 pre-clinical investigations, curcumin is one of the best studied natural products of the whole biomedical literature(2).
As a result, curcumin has emerged as a master switch of addressing the natural inflammation response function, with both a direct and a genomic activity on relevant enzymes, transcription factors and cytokines, as well as at their genomic expression (3). Despite these promising findings, little clinical evidence of efficacy has so far been reported for curcumin, and most of its beneficial effects are suggested by epidemiological studies, supported by studies in animal models, extrapolated from studies in vitro, but not yet validated clinically.(2)
This paradoxical situation is mainly due to the poor absortption of curcumin with a dismally low oral absorption, characterized by plasma concentrations that are barely overcome 50 ng/mL after administration of dosages as high as 12 g/die(4).
Curcumin, just like most dietary phenolics, is sparingly soluble both in water and in oily solvents, but shows polar groups (two phenolic hydroxyl and one enolic hydroxyl) that can interact via hydrogen bondings and polar interactions with complementary group, like the polar heads of phospholipids.
Thus, phosphatidylcholine has a highly polarized head, with the negative charge of a phosphate group and the positive charge of the choline ammonium group, and can complex a variety of poorly soluble phenolics, including curcumin(1).
By embedding curcumin into the environment of phospholipids, the rapid exchange of phospholipids between biological membranes and the extracellular fluids can shuttle it into biological membranes, boosting its cellular captation.
A 2007 study published in the journal Cancer Chemotherapy and Pharmacology(5) demonstrated Meriva®’s superior bioavailability compared to a standardized curcumin extract in rats.
Meriva® improved plasma Cmax and AUC of curcuminoids by 20-fold and levels of curcumin in the liver increased by much more then a 20 folds.
A high oral load of unformulated curcumin (340 mg/Kg) and an amount of Meriva® of 1.8 g/Kg, (corresponding to 340 mg/Kg of curcumin), were administered by oral gavage to Male Wistar rats. The presence of curcumin and metabolites was evaluated at 15, 30, 60 and 120 minutes after administration in plasma, liver and intestinal mucosa. In accordance with previous studies, 99% of curcumin was present in plasma as glucuronides, with the remaining 1% being curcumin sulphate and free curcumin. Complexation with phospholipids led to a marked increase in the concentration of all the plasma curcuminoids (over 23 fold in the case of glucuronides, ca 5-fold in the case of free curcumin, and ca 1.5-fold in the case of sulphates). Since glucuronides are by far the prevailing plasma curcuminoids, the overall bioavailability of curcumin, as expressed in plasma curcuminoids and calculated from AUC values, was improved by over 23-fold when this compound was administered as Meriva® compared to the unformulated natural product.