Could food be used to fight chronic disease?
One of the hallmarks of industrialization, the western diet, is associated with a drastic decrease in the diversity of our gut microbiome. As a result, chronic inflammation, which is implicit in non-communicable diseases, has also risen. As our gut microbiota thrives or dies on what we eat, could introducing foods that support a healthy gut microbiome reduce chronic inflammation?
In a preliminary preprint ahead of publication in a peer-reviewed journal, a team at Stanford University report the effects of high fiber or fermented food diets on microbiome diversity and inflammation using a cohort of 36 participants, where 18 were put on a fermented food diet (an increase from ~0.4 to ~6.3 servings of fermented foods per day), and 21 on a high fiber diet (an increase from ~21.5 g to ~45 g of fiber per day).
Researchers ran Olink's Target 96 Inflammation panel on plasma samples, as well as analyzing the gut microbiomes of all study participants before, during, and after the diet period. Overall, both diets resulted in a change in the microbiome as well as participants’ immune systems. Even further, there were significant correlations between the microbiome and host immune system that indicate a complex relationship between the two.
For example, plasma protein profiles of the high fiber cohort divided the participants into groups according to high or low body inflammation, and it was found that participants in the low inflammation groups had more diverse gut microbiomes. The study also revealed many coordinated host-microbiome relationships, such as that between microbiome-encoded CAZymes and disease-associated proteins. As CAZyme abundance increases, levels of inflammation-associated proteins decrease, suggesting that CAZymes directly affect cells’ response to inflammation cues.
Even more interesting was the effect of the fermented food diet on host immune response. Not only did increasing fermented foods in participants' diets increase microbiota diversity, but it also led to a decrease in inflammation markers. This includes IL-6, a key mediator of chronic inflammation. A decrease in overall endogenous signaling, identified by measuring the activation levels of 15 immune proteins, further suggests a decrease in systemic inflammation in the fermented food cohort.
It is already known that chronic inflammation, a driving factor of non-communicable diseases, is heavily influenced by the gut microbiota, which in turn is influenced by diet. However, the results from this study describe a complex relationship between the host immune system and the gut microbiome, so that by changing diet, one may indirectly impact host immune response. The results from this study are another contribution to the growing body of research on the use of diet as a powerful therapeutic tool to treat chronic inflammation and non-communicable disease.
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Wastyk et al. 2020, Gut Microbiota-Targeted Diets Modulate Human Immune Status, BioRXV