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.
The gut has defenses against
pathogens, but, at the same time, it encourages the survival and growth of
"healthy" gut bacteria.
Of course, these 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 hand, recent research
infers that imbalance 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.
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.
These gut-brain conversations have
been studied for some time. However, a new level to this partnership has
recently been glimpsed; researchers are now considering the influence of our
microbiome on the gut-brain axis. In other words, researchers are asking: do
the bacteria in our gut affect our psychology and behavior?
The question is whether adding beneficial
gut bacteria to an animal can make a difference. Research seems to say yes.
A study published in the Journal of Neurogastroenterology and
Motility, collated the results of studies looking at the effects of
probiotics on central nervous system function in both humans and animals.
They examined 25 animal and 15 human
studies, most of which used Bifidobacterium and Lactobacillus
over a 2-4-week period. Although, as the authors mention, translating animal
studies like this into human terms is a dodgy game. They concluded: "These
probiotics showed efficacy in improving psychiatric disorder-related behaviors
including anxiety, depression, autism spectrum disorder, obsessive compulsive disorder and
memory abilities, including spatial and non-spatial memory."
