Common food additive found to affect gut microbiota

When they say common, my initial research shows that titanium dioxide is present in the most commonly used IBS medication;

Alosetron (Lotronex) Eluxadoline (Viberzi) Rifaximin (Xifaxan) Lubiprostone (Amitiza) Linaclotide (Linzess)

Going further, it's probably in almost every medication, it's an optical whitener, so it makes things look whiter by reflecting more light, it serves no functional purpose beyond aesthetics, white pills are more acceptable than grey or beige. This strikes me as extremely silly, surely people with serious health conditions can appreciate that medication may not be an appealing colour, if it works so well, why does it need to be sold so hard...

Some context

>While TiO2 had minimal impact on the composition of the microbiota in the small intestine and colon, we found that TiO2 treatment could alter the release of bacterial metabolites in vivo and affect the spatial distribution of commensal bacteria in vitro by promoting biofilm formation