Based on the above considerations, we determined several molecular markers of brain in Alzheimer’s disease and observed that the consumption of an HF diet induced oxidative stress, neuronal inflammation, Aβ accumulation, tau hyperphosphorylation, and neuronal cell death, which were significantly alleviated by the consumption of doenjang. Although we did not determine in vivo cognition and memory function, the neuroprotective effects of steamed soybean in most parameters determined in the present study was less potent compared to those of doenjang. The gene discussed is MAPT; the disease is early-onset autosomal dominant Alzheimer disease.