Bioavailability of flavonoids, both in aglyconic or glycosidic form, is reported to be low and erratic due to limited absorption, elevated presistemic metabolism and rapid elimination. Flavonoid aglycons and glycosides, once ingested, reach the small intestine intact and then are metabolized to the methylated, glucuronidated or sulfated metabolites. Flavonoids or flavonoids metabolites that reach the colon are usually further metabolized by local enzymes and then absorbed. This figure is at the base of a non-linear pharmacokinetics and has to be taken into account when evaluating the relationship among in vitro biochemical effects, oral dosages and plasma levels(1).
Previous experiences indicate that the complexation of polyphenolic compounds with phospholipids improves the bioavailability of the natural molecules and stabilize them at intestinal pH values. In order to increase the bioavailability of green tea polyphenols Greenselect® Phytosome® was produced by complexing Greenselect® (a standardized caffeine-free green tea extract) with soy (non-GMO) phospholipids in a 1:2 ratio.
Improvement of radical antioxidant parameter (TRAP) with Greenselect® Phytosome®(2)
Twelve healthy male volunteers were randomly divided in two groups. One received a single dose of Greenselect® (containing 240 mg of tea catechins by HPLC). The second group received 1,200 mg of Greenselect® Phytosome® (containing 240 mg of tea catechins by HPLC). The antioxidant parameter TRAP, mesured as Trolox equivalents, has been evaluated, in the two groups.
A 20% increase of the antioxidative capacity was observed in the volunteers treated with Greenselect® Phytosome® compared to the ones treated with Greenselect® (Chart 5).
- Manach C., Williamson G., Morand C., Scalbert A., Remesy C., “Bioavailability and bioefficacy of polyphenols in humans”, Am. J. Clin. Nutr. 81 (1 Suppl), 230S-242S (2005)
- Pietta P., Simonetti P., Gardana C., Brusamolino A., Morazzoni P., Bombardelli E., “Relationship between rate and extent of catechin absorption and plasma antioxidant status” , Biochemistry and Molecular Biology International 46 (5), 895-903 (1998)