Food protein-based microspheres for increased uptake of vitamin D3. 
To protect vitamin D3 during cold storage and exposure to UV-light, vitamin D3 has been entrapped in microspheres formed by bovine protein β-lactoglobulin (βlg) and lysozyme (Lyso) from egg white.  The behaviour of the βlg/Lyso microspheres in simulated intestinal fluid and their impact on the kinetic release of D3 were determined.  The impact of the D3-loaded βlg/Lyso microspheres on the bioavailability of D3 was evaluated in vivo by force-feeding rats.  The data indicate that the βlg/Lyso microspheres effectively improved the stability of D3, which was readily released in the intestines.  The release kinetics were accelerated in the presence of proteolytic enzymes.  The bioavailability of D3 was improved, as confirmed by the significant increase in the serum levels of 25-hydroxy-D3 in rats.  The current work demonstrates that water soluble proteins were used to substantially increase the bioavailability of the lipophilic vitamin, and thus can serve in the oral delivery of D3.