Different strains of B. breve are widely effective in preventing or ameliorating symptoms of several diseases, including Alzheimer’s disease (i.e., B. breve A1) and obesity-associated insulin sensitivity (i.e., B. breve BR03 and B632) by directly or indirectly modulating the local concentration of SCFAs (Kobayashi et al., 2017; Solito et al., 2021). Here, INS is linked to early-onset autosomal dominant Alzheimer disease.