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 D 2 , D 3 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 D 2 or D 3 . 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 D 3 (0.302 μg/g), whereas in T. molitor neither vitamin D 2 nor D 3 was detectable. UV-B exposure resulted in a significant enrichment of vitamin D 2 in H. illucens meal and of vitamin D 3 in T. molitor meal, depending on spreading density and the exposure time. Concentrations of up to 13.8 μg vitamin D 2 per g and 34.4 μg vitamin D 3 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 D 2 or D 3 . 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.