An interplay of light and temperature: Vitamin D₃ formation in vitro, a model for in vivo plant studies

Vitamin D deficiency is a global issue that requires attention, given its essential functions in the human body. The synthesis of vitamin D₃ in the human skin is subject to limitations related to the availability of UV radiation, which can be particularly limited at higher latitudes, especially during the winter months. Additionally, vitamin D₃ can be acquired through diet. Given that most vitamin D sources are animal-based, the discovery of vitamin D₃ in plants is of particular interest to those following vegan or vegetarian diets. While the characteristics of vitamin D biosynthesis in the human skin are well established, there is a lack of knowledge regarding biosynthesis in plants. This study aimed to evaluate the influence of several factors, including light, temperature, and plant matrix compounds, on the vitamin D₃ conversion reaction. The formation of previtamin D₃ from 7-dehydrocholesterol (7-DHC) was demonstrated to be dependent on UVC and UVB light, while the subsequent formation of vitamin D₃ from previtamin D₃ was shown to be dependent on temperature. Exposure to longer UV wavelengths led to a relative increase in lumisterol content. Furthermore, a concentration-dependent effect of UV-absorbing compounds was observed. These novel insights into the formation of vitamin D₃ will underpin future strategies aimed at optimising vitamin D₃ content in crop species.