|Abstract:||Deficiency and insufficiency of vitamin D (VitD) affect populations worldwide. It is a major health problem in Saudi Arabia. Inadequate VitD3 status has been associated with several chronic disease conditions such as diabetes, autoimmune disease, infectious disease, cancer, and cardiovascular disease, most of which are present in the Saudi Arabian population. Fortification of foods with VitD3 has been present for decades; however, its stability in foods is often compromised by its rapid degradation, low absorption, and poor water solubility. Nano-encapsulation technologies could prove useful to address the shortcomings of current fortification vehicles.
In this study, soy protein isolate was conditioned using pH shifting and ultrasound sonication treatment to create soy protein-based nanoemulsions (SPNEs). The SPNEs were loaded with VitD3 and evaluated in terms of stability, bioaccessibility, bioavailability, bioefficacy, sensory, and physicochemical effects. VitD3 stability was evaluated after UV-B light exposure for 0, 30, 60 and 120 min followed by quantification using and reversed phase HPLC-UV. Bioaccessibility was evaluated in a two-compartment in vitro digestion model. Bioavailability was studied using an animal model of (n=114 rats), in which three groups were compared: SPNEs+VitD3 (2 mL, 150 µg/mL), VitD3 in oil (0.5 mL, 300 µg/mL), and oil without VitD3 (0.6 mL canola oil). The physicochemical characteristics of drinkable yogurt with SPNEs+VitD3 were evaluated against an unfortified control in terms of pH, color changes, viscosity, and titratable acidity. For sensory evaluation, a triangle test was used, in which adult participants (n=62) had to identify the odd sample. Samples were drinkable yogurt fortified with SPNEs+VitD3 (4.2 µg VitD3/100 mL, 30% RDA adults) and their unfortified counterparts. Bioefficacy was evaluated in a single-blind, randomized control, pilot clinical trial (n=39), in which three groups of participants with VitD3 insufficiency received: placebo (drinkable yogurt), VitD3 control in drinkable yogurt (4,000 IU), and VitD3 in SPNEs (4,000 IU) dispersed in drinkable yogurt. Also, the lifestyle behaviors associated with low VitD3 status were evaluated using a VitD questionnaire.
Results indicated that the reduction in particle size and dispersion of VitD3 in SPNEs protects VitD3 from UV-B exposure and increases its bioaccessibility and oral bioavailability. The addition of VitD3 in SPNEs did not influence the physicochemical properties and sensory attributes of fortified drinkable yogurt. The consumption of SPNEs+VitD3 dispersed in drinkable yogurt increased the circulating levels of 25(OH)D3 in subjects with VitD3 insufficiency, more so than the traditional therapy. The application of a validated questionnaire on lifestyle behaviors associated with the potential risk for VitD deficiency and insufficiency was not instrumental in identifying behaviors associated with low VitD3 status. In conclusion, the encapsulation of VitD3 in SPNEs is a promising approach to address VitD3 gaps among at-risk populations via the food supply in Saudi Arabia.