People who consume large amounts of fermented foods improve the variety of microbes in their gut and reduce molecular indications of inflammation.
Academics from Stanford School of Medicine assessed 36 participants who adopted a 10-week meal plan that predominantly contained either fermented or high-fibre foods.
According to the findings, both diets caused contrasting impacts on the immune system and gut microbiome.
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Fermented foods were found to boost the diversity of microbiomes, with bigger portions causing a greater impact. Yogurt, kimchi, kefir, vegetable brine drinks and kombucha tea are some examples of fermented foods.
Chief researcher Professor Dr Justin Sonnenburg said: “This is a stunning finding.
“It provides one of the first examples of how a simple change in diet can reproducibly remodel the microbiota across a cohort of healthy adults.”
The results also showed that smaller amounts of stimulation in four types of immune cells were present in those who followed the fermented food diet.
Additionally, blood tests from the people in the fermented food group showed a reduction in the levels of 19 inflammatory proteins, with type 2 diabetes, rheumatoid arthritis and chronic stress being associated with one of these proteins called interleukin.
Co-researcher Professor Dr Christopher Gardner said: “Microbiota-targeted diets can change immune status, providing a promising avenue for decreasing inflammation in healthy adults.
“This finding was consistent across all participants in the study who were assigned to the higher fermented food group.”
In comparison, the findings reveal that the inflammatory protein levels did not drop in those who implemented a high-fibre meal plan and their microbial diversity altered very little.
Whole grains, legumes, seeds, fruits and vegetables are some examples of food high in fibre.
Dr Erica Sonnenburg said: “We expected high fibre to have a more universally beneficial effect and increase microbiota diversity.
“The data suggests that increased fibre intake alone over a short time period is insufficient to increase microbiota diversity.”