Fig. 4From: Microbiome–host systems interactions: protective effects of propionate upon the blood–brain barrierProduction of propionate by the human gut microbiota. Propionate can be produced directly or indirectly by cross-feeding from succinate and lactate producers (e.g. Selenomonas, Megasphaera and Veillonella spp.). Image produced using information taken from [57]. *Akkermansia muciniphila is known to produce propionate; it is thought to do this via the succinate pathway [57]Back to article page