Recent developments and emerging trends in dietary vitamin D sources and biological conversion

This review elaborates on biochemical characteristics, in vivo metabolism, biological conversion through UV irradiation, as well as dietary fortification of vitamin D. Recent innovations in vitamin D utilization, including nanoencapsulation, direct or indirect addition, emulsion, ultrasound, microwave processing, CRISPR-Cas9 genome editing, as well as UV photoconversion, were summarized. Mushrooms, eggs, yeasts, as well as seafood, such as Barramundi and Atlantic salmon, were typical representatives of original natural food materials for vitamin D bioconversion in relevant research. The critical session thereof referred to the 295 nm UV-B irradiation triggering biological fortification of vitamin D2 and vitamin D3, which occurred in ergosterol from mushrooms, and cholesterol from egg yolk, respectively. The schematic biosynthesis of vitamin D precursors in yeasts regulated miscellaneous enzymes were clearly demonstrated. These summarized pathways played a role as a theoretical primer for vitamin D bioconversion when the UV irradiation technique is concerned. Besides, tomatoes had become the latest potential vitamin D sources after genetic modification. The safety consideration for vitamin D fortified functional food was discussed either. Further research is required to fill the gap of investigating optimized factors like types of eggs, meat, and grain, boarder range of wavelength, and dosage in UV irradiation. Vitamin D has a great potential market in the field of functional food development.