The Efficacy of Nanoemulsion‐Based Delivery to Improve Vitamin D Absorption: Comparison of In Vitro and In Vivo Studies

Scope Vitamin D (VD) is a fat‐soluble vitamin that has a wide range of skeletal and non‐skeletal functions. Although it can be synthesized through sun exposure and obtained from fortified foods, VD inadequacy is epidemic worldwide. Therefore innovative strategies are necessary for improving VD status. The present study examined VD absorption via nanoscale delivery systems. Methods and results We examine the physical characteristics and in vitro bioaccessibility of cholecalciferol (VD3) in nanoemulsion using a simulated gastrointestinal tract system. To evaluate the in vivo bioavailability, we orally administer three groups of mice with VD3 nanoemulsion, VD3 coarse emulsion, or vehicle nanoemulsion without VD3, and the serum 25(OH)D3 is measured using radioactive immunoassay. The nanoemulsion‐based delivery system increases the in vitro bioaccessibility by 3.94‐folds (p < 0.05), as indicated by the concentration of vitamin D3 in micelles. Our animal study shows that, when compared to the vehicle group, the coarse emulsion numerically increases the serum 25(OH)D3 by 36%, whereas the nanoemulsion statistically significantly increases the serum 25(OH)D3 by 73% (p < 0.01). Conclusion Our findings indicate that a nanoemulsion‐based delivery system is a promising approach to improve VD bioavailability, and further studies are warranted to determine its efficacy in humans. In addition to its importance in bone health, Vitamin D (VD) has a wide range of biological functions. About a third of the population in the U.S. is at risk of VD inadequacy. More importantly, even with the wide application of food fortification, VD deficiency is still increasing. This work, including both in vitro and in vivo studies, demonstrates that the nano‐based delivery system improves the bioavailability of VD absorption, and thus has the potential to be utilized as a novel strategy to improve VD status, which remains a critical public health issue in our society.