A diet containing yam reduces the cognitive deterioration and brain lipid peroxidation in mice with senescence accelerated

The aim of this study was to evaluate the effect of a diet rich in yam tuber material Dioscorea alata L. Var. purpurea (M.) Pouch.] on the learning and memory ability of 2‐month‐old male senescence accelerated mice (SAMP8). The mice were fed with three different diets for 12 weeks; a casein diet (control group) and either a casein diet supplemented with 10% lyophilized or with hot‐air dried yam. Results of passive and active shuttle avoidance tests showed the mice fed with the diet containing yam had significantly better learning and memory ability than the control group. The thiobarbituric acid‐reactive substances (TBARS) in the hippocampus of the group fed lyophilized yam were significantly lower than the control and also the group fed a diet containing hot‐air dried yam, whereas the spongy degeneration and the lipofuscin percentage tended to be lower but not significantly different. It was suggested that lyophilized yam was more effective than hot‐air dried yam in reducing the lipid peroxidation, brain pathological changes and the deterioration in the learning and memory ability in mice possibly because lyophilized yam contains more antioxidant compounds.