In vitro assessment of the effect of lactose‐free milk on colon microbiota of lactose intolerant adults

Milk is an essential food, but a large part of adult’s population is uncapable to digest lactose. Lactose intolerance can seriously affect the intestinal ecology and compromise host’s wellbeing. In this scenario, the role of human gut microbiota is crucial, but little is known on that because few are the research studies conducted, either via clinical trials or via in vitro models. Due also to the call to reduce animal testing in science, an in vitro model with gut microbiota of lactose-intolerant adults is necessary. This paper wants to propose an in vitro model coupling oro-gastro-duodenal digestion to colonic fermentation to evaluate lactose impact on colon microbiota of lactoseintolerant adults. Microbiomics and metabolomics in respect to a baseline of fermentation were compared. Generally, when the insult was given, taxa specialized for dairy sugars were unaffected, but Bacteroidaceae and Lachnospiraceae were underrepresented. Lactose triggered raise to opportunistic Proteobacteria, dominated by harmful Klebsiella. Also, an important reduction of essential short chain fatty acids was observed, and in particular that of butyrate. Although, more observations need to be conducted, as well as a comparison with the healthy condition, the present work gives results for pre-clinical application in the sight to reduce animal testin.