This 2021 rodent study investigated diet and stress relationships:

“We show that dietary raffinose metabolism to fructose couples stress-induced gut microbial remodeling to intestinal stem cells (ISC) renewal and epithelial homeostasis. Chow diet (CD) and purified diet (PD) confer distinct vulnerability to gut epithelial injury, microbial alternation and ISC dysfunction in chronically restrained mice.

• We hypothesized that CD components might provide a favorable condition to sustain the expansion of Lactobacillus spp. during stress. We performed a thorough chemical analysis of the diets with special attention to oligosaccharide and polyphenol compounds.
• To understand whether raffinose could underlie diet-shaped epithelial response to stress, we fed mice with raffinose-supplemented PD (RD) and examined effects of chronic restraint stress (RS) on gut epithelial integrity. Mice receiving RD had noticeably increased density of stem cells in the intestine and colon after stress.
• We next investigated whether dietary supplementation with raffinose could recapitulate the effect of CD to increase resilience to epithelial injury. Dietary raffinose abundance appears to be the major factor driving gut microbial and epithelial response to stress.
• A striking change in fructo-oligosaccharide (FOS) and raffinose utilization was intensified after stress. Given the specific increase of fructose after raffinose supplementation to mice, we further explored effects of fructose on intestinal epithelial renewal in stressed mice.

Dietary components and chronic stress interactively modulate gut microbial metabolism and its crosstalk with ISCs. In particular, we identify that dietary raffinose and L. reuteri constitute a metabolic feedforward circuit promoting ISC proliferation via fructose-augmented and engaged glycolysis.

Our data shed light on the dynamic nature of psychological stress-gut microbe crosstalk in adaption to host diets, which highlights diet-microbe interplay in dictating gut response to psychological stress.”

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7801547/ “A diet-microbial metabolism feedforward loop modulates intestinal stem cell renewal in the stressed gut”

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These researchers conducted more than a dozen-and-a-half experiments, with each successively investigating previous ones’ outcomes. One that caught my interest identified raffinose as a major difference between chow and purified diets, which was further investigated.

Our gut microbiota will handle raffinose better than us eating Beano to make raffinose immediately digestible. Lookup raffinose, and you’ll see many more articles condemning it for social purposes than praising it for health purposes.

Experiments weren’t done with soluble fiber as It’s the fiber, not the fat did. There may have been unstudied effects of soluble fiber:

• The two studies’ chow diets were similar; and
• Soluble fiber contents of both purified diet (this study) and refined diets (“It’s the fiber”) were zero, as they contained only insoluble cellulose.

I came across this study by it citing 2018’s Colonocyte metabolism shapes the gut microbiota, which was a notable citation in The future of your brain is in your gut right now.

And 2021 will look like..?