Dried mushrooms exposed to pulsed UV-Radiation generate nutritionally useful concentrations of dietary vitamin D

Background/Aims: There is a high prevalence of vitamin D deficiency in the Asia Pacific region and other parts of the world. Very few natural foods are a good source of vitamin D, with mushrooms as the only major non-animal source known to date. Upon exposure to ultraviolet (UV) radiation, mushrooms produce high levels of vitamin D, often in excess of 10 μg vitamin D/100 g fresh weight equivalent. This project assessed the efficiency of pulsed UV-radiation to generate D-vitamers in dried white button mush-rooms (Agaricus bisporus). Methods: Freshly picked mushrooms (gills enclosed) were air-dried for 22 h, then exposed to 1–4 s of pulsed UV-radiation before being freeze-dried and analyzed by liquid chromatography triple quadrupole mass spectrometer. The concentrations of vitamins D2, D3, D4, 25-hydroxyvitamin D2, and 25-hydroxyvitamin D3 were measured in triplicate. Results: Vitamin D2 increased in a dose-dependent manner as UV-exposure increased (15, 26, and 32 μg/100 g for 1, 2, and 4 s respectively). A similar dose-dependent effect was seen for vitamin D4 (0.9, 1.7, and 2.6 μg/100 g for 1, 2, and 4 s respectively). Both 25-hy-droxyvitamin D2 and 25-hydroxyvitamin D3 were below the limit of detection (LoD). All D-vitamers were below the LoD in control samples (no UV-exposure). Conclusions: UV-exposed dried mushrooms could be a nutritionally useful source of vitamin D, with 100 g fresh weight (about 3–4 medium mushrooms) providing more than the typical daily requirements for vitamin D (10–20 μg/day, depending on age). Pulsed UV-radiation offers an effective method for commercial production of vitamin D-enhanced dried mushrooms.