Bioavailability by design - Vitamin D₃ liposomal delivery vehicles

Vitamin D3 deficiency has serious health consequences, as demonstrated by its effect on severity and recovery after COVID-19 infection. Because of high hydrophobicity, its absorption and subsequent redistribution throughout the body are inherently dependent on the accompanying lipids and/or proteins. The effective oral vitamin D₃ formulation should ensure penetration of the mucus layer followed by internalization by competent cells. Isothermal titration calorimetry and computer simulations show that vitamin D₃ molecules cannot leave the hydrophobic environment, indicating that their absorption is predominantly driven by the digestion of the delivery vehicle. In the clinical experiment, liposomal vitamin D₃ was compared to the oily formulation. The results obtained show that liposomal vitamin D₃ causes a rapid increase in the plasma concentration of calcidiol. No such effect was observed when the oily formulation was used. The effect was especially pronounced for people with severe vitamin D₃ deficiency.