The Study
Gut-microbiota-targeted diets modulate human immune status
This study is like a science experiment where two groups of people ate different diets—either lots of fiber or lots of yogurt and kimchi—and scientists checked their guts and immune systems before and after. It shows that the diets changed things, but it doesn’t prove one diet definitely causes a health benefit for everyone.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Scientists gave people either lots of fermented foods (like yogurt and kimchi) or lots of fiber (like beans and veggies) for 10 weeks to see how their guts and immune systems changed.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 572 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1More gut bacteria diversity and lower inflammation may help prevent chronic diseases common in modern societies, like diabetes and heart disease.
- 2People who ate 6.3 servings of fermented foods daily had more diverse gut bacteria and lower levels of inflammation markers.
- 3People who ate 45g of fiber daily had more bacterial enzymes to break down plants but no increase in bacterial diversity.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Cell
Year
2021
Authors
Hannah C. Wastyk, Gabriela K. Fragiadakis, Dalia Perelman, Dylan Dahan, Bryan D. Merrill, Feiqiao B. Yu, Madeline Topf, Carlos G. Gonzalez, William Van Treuren, Shuo Han, Jennifer L. Robinson, Joshua E. Elias, Erica D. Sonnenburg, Christopher D. Gardner, Justin L. Sonnenburg
Related Content
Claims (4)
In healthy adults aged 51±12 years with high education levels, consuming 6.3 servings of fermented foods daily for 10 weeks increases gut microbiota diversity and reduces circulating levels of IL-6, IL-10, and IL-12b.
In healthy adults, consuming 45 grams of fiber daily for 10 weeks increases the activity of gut microbes that break down carbohydrates and raises the amount of microbial protein in stool, without increasing the number of different microbial species.
Eating fermented foods increases the variety of microbes in the gut of healthy adults by altering the existing microbial environment, not by introducing new microbes directly from the food.
In healthy adults, the initial diversity of gut bacteria determines how the immune system responds to a high-fiber diet: those with less diverse bacteria show stronger immune activation, while those with more diverse bacteria show weaker immune activation.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.