New findings are emerging about the ways fermentation altersvarious foods pre-consumption, and in turn, the ways in which fermentation-enriched chemicals (such as lactoferrin and bioactive peptides) and newly formed phytochemicals (unique flavonoids) may act upon our own intestinal microbiota profile.

“The long and short of it is that there are more and more studies coming out indicating that fermentation may create new bioactive chemicals, which are related to wonderful phytochemicals,”​ Alan C. Logan, co-author of the report, told NutraIngredients-USA. “New formation of these sister-like structures can have health-promoting properties. But the secondary piece of this discussion is how might these newly formed biochemicals affect microbiota?” ​

A growing number of studies support that the gut microbiota and specific beneficial microorganisms may positively influence brain function, via both direct and indirect pathways. Meanwhile, a separate line of research is linking traditional dietary habits to lower risk of mental health disorders, most notably depression and anxiety. But these two areas of research have historically placed very little focus on the microbial characteristics of traditional diets, which were rich in fermented foods.

“One side is talking about traditional dietary patterns, the other talking about microbes. By virtue of fact that traditional dietary patterns have been shown to have beneficial effects on gut microbes, to what extent is there an overlap between this ongoing research?”​ Dr. Logan said.

In the search for a veritable “silver bullet” probiotic or ideal fecal microbiota transplant material (ecobiotic) to help with depression and other mental health disorders, researchers have overlooked the microbial content of traditional diets.

Traditional fermented foods biologically active in various ways​

It’s well-established, for example, that with traditional dietary patterns, fermentation can magnify protein quality and the bioavailabity of mood-regulating B vitamins, magnesium and zinc, but it is also becoming clear that the Lactobacillus species isolated from traditional fermented foods are biologically active in other ways. For example, when eaten, Lactobacillus plantarum strains isolated from traditional Chinese fermented foods provide strong antioxidant protection in animals.

Furthermore, the authors noted that 35% of all lactic acid bacteria from raw fruits and vegetables can survive the conditions of stomach acidity. Though they were careful not to suggest that all of those bacterium have specific probiotic properties, they pointed out that consuming traditional unprocessed and fermented foods may increase the gut microbial diversity now linked to health promotion.

And we've likely only scratched the surface here, Dr. Logan added.

“Fermented dairy has certainly received well-justified attention for its probiotic benefits and is already understood by consumers, but there are other foods out there” ​whose antioxidant and anti-inflammatory activities can be boosted by fermentation, he pointed out. “But the fact that researchers isolated a strain of bacteria from kimchi and found it had an influence on brain neuropeptides is remarkable, highlighting that there may be other untold effects. That’s just one microbe from one fermented Asian dish.”​

Calling the report something of a “springboard” to encourage additional research, Dr. Logan said he hopes that more than anything, the report fosters “more communication between the two research camps on the exciting potential of their efforts.” ​

Source: the Journal of Physiological Anthropology

“Fermented foods, microbiota, and mental health: ancient practice meets nutritional psychiatry”​

Authors: Eva M Selhub, Alan C Logan and Alison C Bested