Colonization of AD mice with Bifidobacterium pseudolongum (B. pseudolongum), a probiotic bacterium significantly promoted by TRF, could mimic the ameliorating activity of TRF on AD‐induced cognitive dysfunction via producing propionic acid (PA) with specific targets on free fatty acid receptor 3 (FFAR3) activation. The gene discussed is FFAR3; the disease is Alzheimer disease.