The new review is the work of researchers based in Bengaluru, India and in North Dakota in the US. The research was published in the journal Frontiers in Pharmacology.
The researchers noted that there are a plethora of molecules that fit into the category they referred to as non-digestible oligosaccharides (NDOs). These include fructo-oligosaccharides, xylo-oligosaccharides, isomalto-oligosaccharides, manno-oligosaccharides and pectic-oligosaccharides among others.
Clinically relevant prebiotic dosages hard to achieve from foods alone
The molecules are present in many plant sources, but the researchers noted that consuming the whole plant sources will rarely yield dosages of these molecules that have clinical significance. Most of the prebiotic effects would thereby be delivered by isolated or synthesized fibers, the researchers said.
The researchers noted that most of the evidence on prebiotic effects has looked a mechanisms within the gut itself. But with the growing appreciation of the importance of the gut-brain axis, more research is starting to be done in this area.
Most animal and all human studies date only from 2014
Starting with in vivo animal studies, the research team found 17 studies that have been done in various models, with most studies done in mice and rats. One study was done in piglets, with another in the C. elegans nematode model. The earliest studied in this group were done in 2007, with the rest done from 2014 onwards.
These studies found that prebiotic supplementation had positive effects on markers of anxiety and depression, brain chemistry markers that correlate to memory, improved markers of oxidative stress in brain tissues and other cognitive and emotional health endpoints.