molecular explanations of whether such shifts represent cause or effect of the disease itself are limited

move away from identifying correlative relationships between characteristics of the microbiome and system-level processes, and towards identifying more causative and mechanistic relationships

relationships between characteristics of microbiomes and the system-level processes that they influence are often evaluated in the absence of a robust conceptual framework and reported without elucidating the underlying causal mechanisms. The reliance on correlative approaches limits the potential to expand the inference of a single relationship to additional systems and advance the field