gut microbes feed each other to compensate for deficiencies and to change host behavior

[corybroo]

How gut microbes feed each other to overcome dietary deficiencies, change host behavior and improve reproduction    

 show that two gut bacteria establish a metabolic cross-feeding that enables them to grow in diets that lack the nutrients that are essential for their growth and to allow them to change host decision making and reproduction. 

bacteria could only affect the decisions of the animal when they were present in specific combinations.

found that flies deprived of single essential amino acids develop a strong appetite for protein-rich foods. However, in flies that were associated with two bacteria that are very abundant in the microbiome (Acetobacter pomorum and Lactobacillus plantarum) their preference for protein was drastically reduced and they prefered to eat sugar.

shown that it is typically necessary for a community of bacteria, rather than isolated bacteria, to produce an effect on the host behavior

found that the two bacteria exchange metabolites, and that this cross-feeding (syntrophy) enables them to grow and act on the animal even if diets lack the nutrients that are essential for them. Specifically, we now understand that Lactobacillus strains produce lactate, which is used by the Acetobacter strains to synthesize amino acids and other metabolites. These are then used by the Lactobacillus strain which cannot synthesize them to continue to produce lactate. Furthermore, these bacterial amino acids are very likely used by the animal for egg production.

By establishing this cross-feeding relation, the bacterial community becomes resilient to drastic dietary changes enabling their growth in the intestines of animals that ingest diets that lack nutrients that are essential to their survival. Ribeiro adds, "It is well-established that our diet affects both the microbiome and our brain. What makes it complicated is the microbiome then in turn affects how diet affects us, and what animals decide to eat. This makes it a very complex puzzle to solve. But by combining the right technologies with the right experimental system we can get at the heart of the mechanisms by which the microbiome interacts with our diet to affect our brain and our body. Importantly, we show that the right associations of bacteria can make the microbiome resilient to dietary perturbations, explaining why some animals and people might be more sensitive to the nutrient content of food than others.

[TomBAvoider]

This is super interesting, thanks corybroo. I have often thought about the puzzle of the so-called "picky eaters". These are often folks, especially the extreme ones, who have super restricted diets, which on the face of it seem absurdly deficient in key nutrients. And yet, somehow these folks live on without any obvious physical problems, sometimes living on to a normal lifespan. I've even known a couple of such people. And when I say absurdly deficient diets, I'm not kidding. Like it makes no sense that someone could eat this poorly and live without obvious disease that's the result from dietary insufficiency. This whole new variable of microbiome puts an entirely different light on this puzzle. It's entirely possible, that for some of these folks, their microbiome adjusted to their super deficient diet and has compenated to an extreme degree and is able to supply just enough metabolites to make this work. 

In general, one could say the same thing not just about picky eaters, but about the majority of SAD consumers. Because if you look closely, the SAD diet is often deficient in nutrients to the point where you'd imagine serious health problems result. But maybe this is not counting on the microbiome - that's a new variable. 

Yet again, we must acknowlegde that we know ridiculously little about nutrition. YMMV.

Edited August 26, 2020 by TomBAvoider

[Ron Put]

Interesting, although symbiosis is nothing unusual, even among bacteria.  Neither is the fact that the microbiome influences brain functions, among other things.

While genetics apparently is important, one's diet appears to be more important and it has a very significant impact on the individual microbiome and health.  Many kids reared on fast food exhibit ill-health compared to their healthy-eating peers, but family and community norms are strong and likely to make obesity and the resulting health issues appear "normal" in some instances.  Without a significant change in one's environment and without the capacity to learn and change habits accordingly, it's unlikely that the voices of one's bacteria will be loud enough on their own to turn them into healthy vegans.