Yogurt companies use that information in the sales pitch for their product, claiming it can help keep your gut bacteria happy
The bacteria growing on our skin have also been effectively exploited to sell the underarm deodorants without which we can become, ahem, malodorous
Until fairly recently our various microbes were thought of as freeloaders without any meaningful benefit to our functioning as healthy human beings.
However, that view has changed in a big way
over the last couple of decades.
Interest in, and knowledge about, the microbiota
has recently exploded. These highly diverse communities of microbes live in and on us in staggering numbers; researchers now estimate that a typical human body is made up of about 30 trillion human cells
and 39 trillion bacteria.
We now recognize they’re essential to our health, participating in many important physiological functions such as digestion and metabolism of foods, and immune responses and inflammation; disruption of the gut microbiota might then contribute to a variety of conditions including childhood asthma, obesity, colitis and colon cancer
New research is beginning to show that the composition and activity of the microbiota exhibits a daily, or circadian, rhythmicity
, just like we do. This offers one pathway to explain a Pandora’s box of possible adverse health effects from aspects of modern life, such as eating late at night or too much electric light after sunset.
The microbial daily routine
The microbiota is primarily bacterial but also includes viruses and eukaryotes like yeast
; the latter are much bigger and more complicated than bacteria, and have a structure similar to our own cells. The total DNA complement of the microbiota is termed the microbiome
, and it’s what we study to learn about the inner workings of the microbiota.
In this field’s early days, researchers took fecal samples from people to investigate the composition of the gut microbiome
. Later they noticed that defining the microbiome from a sample taken in the morning was quite different from one taken in the evening: The gut microbiota was not static
over the span of the day.
This is particularly true in the science of DNA. In order to count trillions of microbes as well as distinguish among hundreds of different species, there are four broad requirements: conceptual development
, sequencing machines
, analytic approaches
and supercomputers to conduct the near hopelessly complex statistical analyses.
Each of these has advanced to an extent that now studies like the one from the Weizmann Institute are achievable.
The key conceptual breakthrough in analyzing the microbiome came with the recognition that the complex array of so many different organisms living together in a community may not be reducible
In other words, it doesn’t appear possible to separate out only one bacterial species from the group, and understand how it functions in isolation. The community works as a whole.
For example, some of its members are bacteria that cannot absorb iron, which is necessary for growth. They require iron-binding molecules made by other members of the community to survive. So you can’t grow this guy in a Petri dish by itself.
Gut and rhythm
The findings of the new study from Israel, which extends previous exciting work in this area, are relevant to humans for many reasons.
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For example, people who must take antibiotics for extended periods, or shift workers who eat at the “wrong” time of day, may be at risk via these microbiome pathways.
In both instances, there will be changes in their metabolism that could lead, perhaps, to higher risk of obesity and metabolic syndrome, both of which have been shown to be in excess in night workers
A root cause of these human health issues we see on the macro scale may be our gut microbiota and whether or not it is happy.