Abstract
As a neurodegenerative, autoimmune disorder, multiple sclerosis (MS) has been linked to the gut-brain axis through the gut microbiota, which is critical for immune system development. Shifts in microbiome composition related to disease and diet have been associated with differential health outcomes; however, their combined effects remain largely unknown. In this study, we investigated whether lactose intolerance (LI), a common dietary restriction, differentially affects the gut microbiome of individuals with MS compared to healthy controls. Using 16S amplicon sequencing data obtained from Zhou et al. (2022), we analyzed gut microbiome diversity, composition, and function across four groups: Healthy No Dietary Restrictions (HNDR) compared to Healthy Lactose Intolerant (HLI), and MS No Dietary Restrictions (MSNDR) compared to MS Lactose Intolerant (MSLI). The results for alpha diversity metrics (Observed, Shannon index) were not significant. Beta diversity metrics (Bray-Curtis) were also insignificant between MSNDR and MSLI, although a significant difference was found between HNDR and HLI. Taxonomic shifts between no dietary restriction (NDR) and LI individuals in both the healthy and MS groups were observed to be minimal, further supported by the overlapping genera found from the core microbiome analysis and the lack of significance in differentially abundant taxa. Functional analyses revealed that there were no significant metabolic pathways pertaining to any taxa. The results suggest that diversity, composition, and function of the human gut microbiome in patients with MS are largely unaffected by lactose intolerance.