Analysis results of vitamin d (d2, d3) in cultivated wood ear mushrooms - after 3 hours of uv irradiation –

The 2015 edition of the Japanese Dietary Reference Intakes recommended a daily intake of 5.5g of vitamin D. However, due to the COVID-19 pandemic, people have restricted their outings, spent more time at home, and taken more frequent precautions against ultraviolet (UV) radiation, such as using umbrellas and hats, when going outside. The 2025 edition of the Japanese Dietary Reference Intakes recommends a daily intake of 9µg of vitamin D. To increase vitamin D intake from food, we cultivated wood ear mushrooms, which are thought to have a high vitamin D content, and analyzed their vitamin D content at the National Food Research Institute, but the levels were below the detection limit. Therefore, this study aimed to clarify whether the vitamin D (vitamin D2 and vitamin D3) content of wood ear mushrooms (sun-dried) cultivated in the past would increase by irradiating them with UV light (253.7nm) using an indoor UV irradiation device. As a result of this study, the vitamin D (vitamin D2 and vitamin D3) content of cultivated wood ear mushrooms irradiated with UV light (253.7nm) for 3 hours was 236µg/100g, which is more than double the vitamin D content listed in the Japanese Food Composition Table. In the future, considering the use of domestically produced wood ear mushrooms as disaster food and space food, we aim to enhance their value as a food ingredient by managing factors such as "moisture content," "grinding particle size," and "UV irradiation conditions" to maximize the nutritional value of vitamin D2.