Enhanced bioavailability of a krill oil-based milk thistle extract formulation: in vitro and human studies

The milk thistle plant (Silybum marianum) is known for its hepatoprotective properties. However, the poor water solubility of silymarin limits its dissolution in the intestinal tract and restricts its bioavailability following oral administration.

To improve bioavailability, special formulations, in particular micellar solubilization, are explored. In this study, we examined the transport rate of silymarin in a krill oil-based formulation across a Caco-2 epithelial barrier after upstream digestion simulation in vitro. Furthermore, in a randomized cross-over design study the bioavailability of the krill oil-based formulation was investigated after single dose intake in fasting conditions in healthy participants.

We could demonstrate that the apparent transport coefficient of silybin, measured as lead substance of milk thistle extract, across the epithelium is efficiently boosted by a krill oil formulation, resulting in a 28% increase compared to silymarin powder. Consistent with these findings, a significant enhancement of bioavailability (P < 0.0001) was demonstrated for the krill oil-based formulation in comparison to the milk thistle extract resulting in an 8.59-fold higher AUC_0-8h and a 15.08-fold greater C_max of silybin and faster uptake kinetic after single dose intake.

These findings suggest that phospholipid-based delivery systems offer a promising strategy for improving the efficacy of lipophilic bioactives. Furthermore, the combination of krill oil with milk thistle extracts efficiently provides silybin, PUFAs, and choline, which are important nutrients contributing to liver and heart health.