Figure 3: Increase in vitamin D2 content of sliced white button mushrooms exposed to sunlight by consumers at different geographic locations compared to predicted increase (3.10 + 3.92*UVindex*exposure time), assuming UV indices of 7 and 3 for “mostly clear” and “mostly cloudy” conditions, respectively. Letters in parentheses in legend refer to corresponding experiments in Table 1. DRI= Dietary Reference Intake [20].