The question that got me started down this rabbit-hole was an article about the complexities of maintaining our fecal microbiome. That is, maintaining a stable ecosystem of fecal bacteria (mostly).
The human microbiome has been implicated in Irritable Bowel Syndrome, Crohn's Disease, Obesity, Autism, Bowel and Rectal Cancer....Flatulence, Strokes....and on, and on, and on.
It isn't enough to eat a spoonful of yogurt every day. That is like throwing a handful of seeds into the yard and expecting to harvest a field of wheat.
This peer-reviewed article looks at some of the factors that impact bacterial recolonization of material entering the ascending colon from the small-intestine.
Here are the "images" from the article:
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Dashed lines indicate "typical" flow velocities and mixing rates in the ascending colon |
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Graphic illustrating mechanisms in play. Material entering the large bowel is very soupy and the volume at the exit is (typically) is reduced to 1/5th the entering volume by way of water removal. |
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The ellipse encloses the range of measurements of people who characterized themselves as "healthy" |
Among the factors NOT considered in this study were fiber particle size and the mixing from exercise.
Some of us experience more dental issues as we age and we don't chew our food as thoroughly as we did/could as when we were younger. Bacteria can only access the particle from its exposed surface, so even if there was "plenty" of fiber from a mass standpoint, if the particles are large then those nutrients are not very accessible to the various bacteria in our guts.
Another thing that can happen as we age is that we sit in our recliners as we eat while we watch TV and we don't pay attention to what is in our mouth. It is reasonable to hypothesize that we might not chew our food as much when we are distracted.
Another thing that has changed in the last sixty years is that nearly everybody has a "recliner" or La-Z-Boy or Barka lounger. They used to be called "invalid chairs" but now they are very, very common even for able-bodied people.
Sitting in a recliner lulls our core, stability muscles to inaction. Continuing the hypothesis, the inaction of those muscles slows the passage of food through our guts and also throws the entire burden of ascending-bowel content mixing upon the spasming of the lower-bowel walls.
These conditions are very different from the conditions our bodies were designed for (or evolved under) and it should not be surprising if we get suboptimal performance from them.
Where is the medical science?
Where is the money?
Most of the science seems to be directed at looking for the BEST strains of bacteria to load into fecal transplants. Those strains could then be patented and turned into income-streams.
There is no money to be made in coaching people to eat a balanced diet (adding vegetable fiber if you are eating a meat-centric diet), getting dental work done if indicated, turning off the TV, sitting at the table, chewing your food and taking a walk optimally timed to speed up the slinky of incoming food through the processes.