USDA experiments have shown that exposing certain mushrooms to UV light converts cholesterols in the mushrooms to vitamin D. Since sunlight contains UV, an easy

USDA experiments have shown that exposing certain mushrooms to UV light converts cholesterols in the mushrooms to vitamin D. Since sunlight contains UV, an easy solution would be to leave some portabella mushrooms out in the noonday sun for a while. So far I can't find any articles that give a precise number for how long the mushrooms were exposed, though. [1] http://www.ars.usda.gov/ARSUserFiles/80400525/Articles/AICR09_Mushroom_VitD.pdf http://www.ars.usda.gov/ARSUserFiles/80400525/Articles/AICR0... [2] https://www.ars.usda.gov/research/publications/publication/?seqNo115=260850 https://www.ars.usda.gov/research/publications/publication/?... [3] https://fdc.nal.usda.gov/fdc-app.html#/food-details/169377/nutrients https://fdc.nal.usda.gov/fdc-app.html#/food-details/169377/n...