Diet rapidly and reproducibly alters the human gut microbiome.
Level 3 - non-randomized controlled study
Short-term human dietary intervention trial (randomization not specified in abstract)
PubMed 24336217 · doi:10.1038/nature12820
What was done
Human participants consumed short-term diets composed entirely of either animal products or plant products to evaluate how rapidly and reproducibly macronutrient changes alter gut microbial community structure, gene expression, and microbial activity.
What was found
The abstract reports qualitative shifts without specific numerical values, sample sizes, or effect sizes. The animal-based diet increased the abundance of bile-tolerant microorganisms (Alistipes, Bilophila, and Bacteroides) and decreased plant-polysaccharide-metabolizing Firmicutes (Roseburia, Eubacterium rectale, and Ruminococcus bromii). Changes in microbial activity reflected trade-offs between carbohydrate and protein fermentation. Additionally, foodborne bacteria, fungi, and viruses transiently colonized the gut, and the animal-based diet increased the abundance and activity of Bilophila wadsworthia.
Why it matters
This study shows that the human gut microbiome can rapidly alter its taxonomic composition and metabolic gene expression in response to acute macronutrient shifts, providing mechanistic insight into how diet influences bile-tolerant and inflammatory-associated microbes.
Limits
The abstract does not state the sample size (n), participant demographics, intervention duration, or quantitative effect sizes and confidence intervals. Long-term clinical health outcomes were not evaluated.
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