Gut bacteria and the brain: Are we controlled by microbes?


ALTHOUGH the interaction between our brain and gut has been studied for years, its complexities run deeper than initially thought. It seems that our minds are, in some part, controlled by the bacteria in our bowels.
How much sway can a microbe hold?
The gut has defenses against pathogens, but, at the same time, it encourages the survival and growth of “healthy” gut bacteria.
The vast majority of these single-celled visitors are based in the colon, where no less than 1 trillion reside in each gram of intestinal content.
Estimating the number of bacterial guests in our gut is challenging; to date, the best guess is that 40 trillion bacteria call our intestines home – partially dependent on the size of your last bowel movement (poop’s major ingredient is bacteria).
To put that unwieldy number into perspective, our bodies consist of roughly 30 trillion cells. So, in a very real sense, we are more bacteria than man.
Most of our gut bacteria belong to 30 or 40 species, but there can be up to 1,000 different species in all. Collectively, they are termed the microbiome.
Of course, bacteria do benefit from the warmth and nutrition in our bowels, but it is not a one-way relationship – they also give back.
Some species benefit us by breaking dietary fiber down into short-chain fatty acids that we can then absorb and use. They metabolize a number of compounds on our behalf and play a role in the synthesis of vitamins B and K.
On the other side of the fence, recent research infers that dysregulation of gut bacteria might be an important factor in inflammatory and autoimmune conditions.
The microbiome’s role in health and disease is only slowly giving up its secrets. The latest and perhaps most remarkable finding is the ability that gut bacteria have to moderate our brain and behavior.
Why should the gut and brain be linked?
The goings on in our guts are a matter of life or death. If the gut is empty, our brain must be told; if there is a problem with our gut that will hinder food processing and therefore nutrition absorption, the brain will need to be informed. If our gut is facing a pathogen attack, our brain should be kept in the loop. The links between our gut and brain are hormonal, immunological, and neural, via the central nervous system and the enteric nervous system, which governs the function of the gut. Collectively, they are termed the gut-brain axis.
Although, at first glance, the connections between the gut and brain might seem surprising, we have all experienced it in action.

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