Does Consuming Fresh Ultraviolet Light-Exposed Mushrooms Offset the Seasonal Decline in Serum Total 25OHD in Adults Classified as Overweight and Class I Obese? Results from a Randomized Controlled Trial

We assessed whether consuming UV light-exposed mushrooms (UVMs) would offset the seasonal decline in circulating total 25-hydroxyvitamin D (25OHD), an index of vitamin D status. During late fall and winter, 41 adults (19 M/22 F, age 43 ± 11 y, BMI 29.8 ± 5.9 kg/m2, mean ± SD) were randomized to consume either 84 g of fresh Agaricus bisporus twice/d (produced to contain 400 IU of vitamin D2/serving; 800 IU/d total) or 1 tsp of breadcrumbs twice/d (Control) while continuing to consume their self-chosen diets. At baseline and week 6, fasting serum 25OHD2, 25OHD3, and total 25OHD were measured. Mushrooms were sampled weekly and vitamin D2 content measured. From the intent-to-treat analysis (Mushroom group, n = 20, and Control group, n = 21), 25OHD2 increased and 25OHD3 decreased in the Mushroom group over winter months compared to Control with no differences in the decrease in total 25OHD between groups. Unexpectedly, only 67% of the UVMs contained vitamin D2. Post hoc subgroup assessment indicated that participants consuming UVMs (n = 11) had increased 25OHD2 and a greater decline in 25OHD3 compared to subgroups consuming mushrooms without vitamin D2 (n = 9) and Control (n = 21), with no differences in the decrease in total 25OHD among subgroups. Consuming UVMs increased serum 25OHD2 but did not prevent a seasonal decline in vitamin D status due to a greater decrease in 25OHD3.