From what I've understood from one particular (very early) experiment of living on just potatoes for a year is that it worked because (for some reason) the part

From what I've understood from one particular (very early) experiment of living on just potatoes for a year is that it worked because (for some reason) the participants had, or developed, a particular gut microbiome which could transform some of the potato starch to additional nutrients which their bodies could then use.