Myo- and cardiotoxic effects of the wild winter mushroom ( Flammulina velutipes) on mice.

Rhabdomyolysis (destruction of striated muscle) is a novel form of mushroom poisoning in Europe and Asia indicated by increased circulating creatine kinase levels. Particular wild fungi have also been reported to induce elevated creatine kinase activities in mice. Flammulina velutipes (enokitake or winter mushroom) is one of the most actively cultivated mushroom species globally. As it is marketed as a medicinal mushroom and functional food, it is important to examine whether it could induce potentially harmful health effects similar to some previously studied edible fungi. The present study examined the effects of F. velutipes consumption on the plasma clinical chemistry, hematology, and organ histology of laboratory mice. Wild F. velutipes were dried, pulverized, mixed with a regular laboratory rodent diet, and fed to the animals at 0, 3, 6, or 9 g/kg body mass/day for five days ( n = 6/group). F. velutipes consumption caused increased activities of plasma creatine kinase and the MB-fraction of creatine kinase at 6-9 g/kg/d, indicating potentially deleterious effects on both skeletal and cardiac muscle. The plasma total and high-density lipoprotein cholesterol concentrations (at 9 g/kg/d) and white blood cell and lymphocyte counts (at 6-9 g/kg/d) decreased. Although the cholesterol-lowering properties of F. velutipes can be beneficial, the previously unexamined, potentially hazardous side effects of mushroom consumption (myo- and cardiotoxicity) should be thoroughly investigated before recommending this mushroom species as a health-promoting food item. Impact statement This work is important to the field of functional foods, as it provides novel information about the potential myo- and cardiotoxic properties of an edible mushroom, Flammulina velutipes. The results are useful and of importance because F. velutipes is an actively cultivated mushroom and marketed as a health-promoting food item. The findings contribute to the understanding of the complexity of the balance between the beneficial and potentially harmful effects of mushroom consumption.

Evaluation of reproductive safety of beta-sitosterol on the American mink (Neovison vison).

beta-Sitosterol is a weakly estrogenic phytosterol used extensively in functional foods to lower elevated serum cholesterol concentrations due to its inhibitory action on intestinal cholesterol absorption. It caused previously decreased sex steroid concentrations in fish and lowered sperm counts in rats. In the American mink (Neovison vison), litter size increased slightly due to dietary beta-sitosterol supplement. The aim of the present experiment was to conduct a dose-response study on the effects of beta-sitosterol on the reproduction of the American mink. Juvenile male and female mink (n=480) were exposed to 0, 5, 10 or 50 mg of peroral beta-sitosterol kg(-1)d(-1) for 10 months. After 3 months of exposure in November, 15 males per group were sacrificed and general biochemical variables reflecting overall health were determined. The beta-sitosterol-treated male mink had increased absolute and relative masses of intraabdominal fat and higher blood hemoglobin and serum high-density lipoprotein cholesterol concentrations. In spring, the top-rated male mink were mated with multiple females within each study group and reproductive success was assessed. No differences in the reproductive performance of the males (10-11 per group) or females (47-50 per group) could be detected in the exposed groups and the kits of all groups developed in a similar manner. The results suggest that dietary beta-sitosterol presents no significant risk to mammalian fertility.