Are “Free From” Foods Risk-Free? In Vitro Lactose-Free Milk Fermentation Modulates Normal Colon Microbiota

Nowadays, consumption of “free from” foods by non-specific consumers is increasing, also due to misperception of labels that seems that the foods are healthier. These foods are formulated for allergic or diseased consumers, and it is not known if there are more benefits than risks for normal ones. For example, there is no work presenting the interplay of lactose-free milk with the colon microbiome of healthy people. To focus on the eventual modulation of intestinal microbiota of normal subjects by lactose-free milk, we performed an in vitro simulation of digestion and fermentation powered by microbiomics and metabolomics approaches to study changes of gut microbiota in bacterial populations and production of metabolites. Results indicated that lactose-free and lactose-containing milk differently modulated colonic microbiota by several microbiological indicators, including the reduction of Bifidobacteriaceae and Lactobacillales and the reduction of beneficial production of microbial compounds. Such features suggest that lactose-free milk increases the risk of dysbiosis in normal subjects. Our work scouted the culprits of this dysbiosis among hundreds of molecules and microbes of the gut microbiota, giving names and niches for the first time. It employs an in vitro model which is the new dictate of sustainable research and improves translatability. Our findings support the European Society for Clinical Nutrition and Metabolism (ESPEN) guidelines that do not suggest regular consumption of lactose-free diets if no intolerance is identified.