Effects of high vitamin D2-enriched shiitake mushroom soup on raising the serum 25-hydroxyvitamin D levels in vitamin D-deficient healthy adults: a clinical study

Abstract In this study, vitamin D2-enriched shiitake [Lentinula edodes L. (Berk.)] soup was optimised for its cooking duration to minimise vitamin D2 loss and help improve serum 25-hydroxyvitamin D (25OHD) levels in vitamin D-deficient healthy adults. The nutritional composition and microbiological evaluation of UV-B irradiated shiitake powder and the formulated soup (32,024 ± 20 IU D2/20g sachet) were determined to ensure their safety for consumption. To assess bioavailability, 53 vitamin D-deficient patients (≤50 nmol/L) were randomised to three treatments: (a) irradiated shiitake soup, (b) vitamin D2 supplement, and (c) placebo shiitake soup for 5 weeks. After four consecutive weeks, vitamin D2 shiitake soup improved 25OHD (30 ± 8.3 to 49.1 ± 21.7 nmol/L), similar to the supplement arm (31.1 ± 7.2 to 44.8 ± 20.5 nmol/L), but there was no improvement in the placebo group (28.3 ± 6.8 to 29.1 ± 11.5 nmol/L). The optimised vitamin D2 shiitake soup effectively improved serum 25OHD, offering a potential solution for vitamin D deficiency.