Exploring insect meals as novel sources of vitamin D: Evaluation of vitamin D precursors, biofortification by UV-B exposure, and in vivo efficacy

Abstract Vitamin D deficiency is a global problem due to limited dietary sources, necessitating the exploration of alternative sources. The objective of this study was to investigate the suitability of UV-B-exposed insect meals as a source of vitamin D. First, two insect meals from Hermetia illucens and Tenebrio molitor larvae were analysed for their concentrations of vitamin D2, D3 and their precursors ergosterol and 7-dehydrocholesterol (7-DHC). Second, the insect meals were exposed to UV-B light to stimulate the synthesis of vitamin D from the precursors. Finally, to determine the efficacy of insect meal-derived vitamin D in contributing to an adequate vitamin D status, UV-B-exposed insect meals were fed to rats for 4 weeks in comparison to pure vitamin D2 or D3. H. illucens meal had a high concentration of ergosterol, whereas T. molitor meal had a high concentration of 7-DHC. H. illucens meal contained vitamin D3 (0.302 μg/g), whereas in T. molitor neither vitamin D2 nor D3 was detectable. UV-B exposure resulted in a significant enrichment of vitamin D2 in H. illucens meal and of vitamin D3 in T. molitor meal, depending on spreading density and the exposure time. Concentrations of up to 13.8 μg vitamin D2 per g and 34.4 μg vitamin D3 per g in H. illucens and T. molitor meal, respectively, were achieved under optimum exposure conditions. The rat study showed that feeding UV-B-exposed insect meals was successful in increasing serum 25(OH)D concentrations. Serum 25(OH)D concentrations were even higher in rats fed UV-B-exposed insect meals than in rats fed pure vitamin D2 or D3. In conclusion, meals from H. illucens or T. molitor contain high amounts of vitamin D precursors which can be converted to vitamin D by UV-B exposure. Thus, UV-B-exposed insect meals could be considered as novel sources of vitamin D for human and animal nutrition.