# Diet-microbiota associations in gastrointestinal research: a systematic review

## TL;DR

This review explores how diet affects gut microbiota and highlights the need for better dietary assessment methods to understand these interactions.

## Contribution

The study identifies gaps in current dietary assessment methods regarding microbiota-relevant nutrients.

## Key findings

- Dietary factors like patterns and nutrients influence gut microbiota.
- Current methods focus on nutrients absorbed in the small intestine, not those relevant to microbiota.
- Expanding food composition databases is needed for better microbiota research.

## Abstract

Interactions between diet and gastrointestinal microbiota influence health status and outcomes. Evaluating these relationships requires accurate quantification of dietary variables relevant to microbial metabolism, however current dietary assessment methods focus on dietary components relevant to human digestion only. The aim of this study was to synthesize research on foods and nutrients that influence human gut microbiota and thereby identify knowledge gaps to inform dietary assessment advancements toward better understanding of diet–microbiota interactions. Thirty-eight systematic reviews and 106 primary studies reported on human diet-microbiota associations. Dietary factors altering colonic microbiota included dietary patterns, macronutrients, micronutrients, bioactive compounds, and food additives. Reported diet-microbiota associations were dominated by routinely analyzed nutrients, which are absorbed from the small intestine but analyzed for correlation to stool microbiota. Dietary derived microbiota-relevant nutrients are more challenging to quantify and underrepresented in included studies. This evidence synthesis highlights advancements needed, including opportunities for expansion of food composition databases to include microbiota-relevant data, particularly for human intervention studies. These advances in dietary assessment methodology will facilitate translation of microbiota-specific nutrition therapy to practice.