Ultraviolet-B radiation, mushrooms, and vitamin D: From technology to bioavailability

We describe an efficient technology to obtain vitamin D2-enriched mushroom powder by exposing postharvest shiitake mushrooms (Lentinula edodes) to UV-B radiation. UV-B exposure took place in a self-designed semi-industrial facility with the required safety measures. The highest vitamin D2 content (1000 IU g−1 DM) was found when a total UV-B dose of 24 kJ m−2 was distributed in two different moments of the process (75% on sliced fresh mushroom and the remaining 25% on the dry powder). Similar results were obtained in king oyster (Pleurotus eryngii) and Portobello button (Agaricus brunnescens) mushrooms, indicating that the developed technology could generally be used to produce vitamin D2 supplements from mushrooms. In addition, the same method increased the vitamin D2 content in shiitake by-products, which could be used for animal feed. The microbiological, toxicological, and nutritional quality of the enriched mushroom preparations were confirmed to ensure a safe consumption. To determine the vitamin D bioavailability in humans, the enriched shiitake powder was encapsulated using 600 mg per capsule, which was equivalent to the minimum daily intake of vitamin D for adults. The capsules were ineffective in improving serum 25-hydroxyvitamin D status, but prevented an excessive decrease in this parameter due to winter conditions.