We are all familiar with phrases such as ‘trust your gut’ or ‘go with your gut instinct’. In The East, the gut has been emphasised as a centre of intelligence in the body for thousands of years. As with many other areas of traditional wisdom, we are now starting to understand the truth of this assertion through modern medical research. It has become clear that our gut plays a major role in our mental, as well as physical health.
Much of our new information comes from the work of Michael Gershon, professor of anatomy and cell biology at Columbia University in New York. According to Gershon, the gastrointestinal tract qualifies as a ‘second brain’ because it is an autonomous nervous system, the only part of the body that can function on its own.
In an interview with The Telegraph on April 15th 2012 Gershon states:
‘When I was at medical school I was taught erroneously that the brain controlled everything – including the gut,’ he says. ‘In fact, if you cut the vagus nerve – the major nerve between the brain and the gut – the gut would soldier on. We now know it can work completely independently of the brain and spinal cord. While the “first brain” gets on with religion, philosophy and poetry, the “second brain” deals with the messy business of digestion.’
Technically known as the enteric nervous system, the “second brain” or gut consists of sheaths of neurons (nerves) embedded in the walls of the digestive tract and contains approx. 500 million nerve cells, more than in either the spinal cord or the peripheral nervous system and as many as there are in a cat’s brain. They help to control muscular contractions in the gut as well as the secretions of glands and cells, absorption of nutrients and expulsion of waste matter. They also help to balance hunger and satiety (the sense of being full) communicating those states to the “big brain”.
Gershon says that we probably evolved this intricate web of nerves to perform digestion and excretion “on site,” rather than remotely from our brains. However, this does not adequately explain the complexity of gut intelligence.
In an interview in Scientific American on Feb 12th 2010, Emeran Mayer, professor of physiology, psychiatry and biobehavioral sciences at the David Geffen School of Medicine at the University of California, Los Angeles (U.C.L.A.), was quoted as follows:
“The system (the gut) is way too complicated to have evolved only to make sure things move out of your colon.”
The interview continues:
‘approx. 90% of the fibres in the primary visceral nerve, the vagus, carry information from the gut to the brain and not the other way around. “Some of that info is decidedly unpleasant,” Gershon says. The second brain informs our state of mind in other more obscure ways, as well. “A big part of our emotions are probably influenced by the nerves in our gut,” Mayer says. Butterflies in the stomach—signaling in the gut as part of our physiological stress response, Gershon says—is but one example. Although gastrointestinal (GI) turmoil can sour one’s moods, everyday emotional well-being may rely on messages from the brain below to the brain above.’
Even more recent research suggests that the gut microbiome (the aggregate of microbes in the gut that are both helpful and potentially harmful) may even act as a conductor of the body’s endocrine (hormonal) system by not only producing a range of different hormones, but also signalling how much of each hormone should be created and released by glands throughout the body (ie thyroid hormones, estrogen, melatonin and cortisol).
It is now clear that the gut influences many physical and mental health issues and we can see interesting areas to explore in both Eastern & Western thought on this subject.
