Bioavailability of vitamin D2 from irradiated mushrooms:: an in vivo study

Vitamin D-2 from irradiated edible mushrooms might present a possible dietary source of this vitamin, subject to its bioavailability. Having previously optimized a method for the conversion of ergosterol in mushrooms to vitamin D-2, this paper examines the vitamin D-enriched mushrooms (Lentinula edodes) for their bioavailability of the vitamin, using an animal model. Thirty male Wistar rats were fed for 1 week with a diet deficient in vitamin D. After this 1-week period, six rats were randomly selected and killed for analysis of initial bone mineral density, and serum level of 25-hydroxyvitamin D. A group of twelve rats of the test animals received 1 mu g of vitamin D-2 from irradiated mushrooms for a period of 4 weeks until being killed. The remaining twelve rats were fed un-irradiated mushrooms at the same level to act as controls. At the end of a 4-week period, the mean serum 25-hydroxyvitamin D level of the experimental group was 129.42 (sd 22.00) nmol/l whereas it was only 6.06 (sd 1.09) nmol/l in the control group. Femur bone mineral density of the experimental group of animals was significantly higher (P < 0.01) than the control group. In addition, serum Ca concentrations among groups were shown to be significantly higher (P < 0.01). It may be concluded from the results that vitamin D-2 from UV-irradiated mushrooms is well absorbed and metabolized in this model animal system. Significant increase in femur bone mineralization (P < 0.01) was shown in the presence of vitamin D-2 from irradiated mushrooms compared with the controls.