UV-B biofortification of edible mushrooms: mechanistic insights, bioavailability, and potential to mitigate vitamin d deficiency

Abstract:

Vitamin D deficiency is a serious global public health concern, caused by inadequate solar exposure, urban lifestyles, insufficient dietary intake, and inconsistent fortification procedures. Vitamin D from natural foods is still scarce, especially among cultures that eat mostly plant-based diets. Edible mushrooms contain ergosterol, a photochemical precursor of vitamin D₂ (ergocalciferol), making them a unique source of nourishment. When exposed to UV-B radiation (280-315 nm), ergosterol opens its photolytic ring to create pre-vitamin D₂, which is then thermally isomerised to vitamin D₂. This review critically synthesises current findings on UV-B biofortification of mushrooms, taking into account mechanistic photochemistry, processing, analytical, and translational issues. Key determinants of vitamin D₂ yield including species variability, tissue morphology, moisture content, UV dose and irradiance, exposure geometry, and post-irradiation equilibration are evaluated to explain heterogeneity across studies and to identify process optimisation constraints. This study examines the post-harvest stability of vitamin D₂ throughout refrigerated storage, drying, and cooking. Packaging, light exposure, and processing conditions are crucial for nutrient retention. In vitro digestive models and human intervention studies show that mushroom-derived vitamin D₂ is bioavailable and can boost circulation 25-hydroxyvitamin D levels, but its efficacy compared to vitamin D₃ is still contested. Finally, we investigate industrial implementation paths, regulatory considerations, and the incorporation of vitamin D₂-enriched mushroom components into food fortification programs. Overall, UV-B-biofortified mushrooms are a mechanistically sound and scalable technique for increasing dietary vitamin D, but they require further standardisation and clinical validation to have a population-wide impact.