Photobiological Characteristics of Vitamin D₂ in Agaricus bisporus and Its Clinical Bioavailability in Humans
Mushrooms exposed to sunlight or ultraviolet (UV) radiation serve as an excellent dietary source of vitamin D₂ due to their high content of ergosterol (provitamin D₂), the precursor of vitamin D. Upon UV irradiation, ergosterol is converted to previtamin D₂, which rapidly undergoes thermal isomerization to form vitamin D₂ via a mechanism analogous to the transformation of previtamin D₃ to vitamin D₃ in human skin. Continuous UV exposure further generates two photoproducts: lumisterol₂ and tachysterol₂. Research shows that lumisterol₂ concentrations remain stable for up to 24 hours after biosynthesis in Agaricus bisporus.
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