The Importance of The Gut
If I could recommend you do one thing, it would be to read Dr. Junger’s book Clean Gut.
I attempted to collate some notes as reference for myself, which I thought might also be helpful to anyone unfamiliar with the book. Handily, Dr. Junger has also recently published a four-part newsletter and cheat sheet.
For my benefit (and hopefully yours), I have summarised some of the highlights here.
The gut is made up of four main parts: the digestive tube, the gut-associated lymphatic tissue (GALT), the intestinal flora and the gut’s nervous system. What are these and why are they important?
The Digestive Tube
Only three major organs come into physical contact with the outside world: your skin, your lungs and your digestive tube. Of these three, your digestive tube is the largest and the busiest. The intestinal wall is also unique in that, unlike the lungs, it is constantly in touch with foreign stuff (food and drink, and all the chemicals we add to both) and foreign organisms (bacteria, yeast, parasites and viruses, amongst others). And unlike the skin, which is designed to keep most things outside and let very few things pass through it, the intestinal wall us designed to absorb everything that is useful to your body.
Along this border, some of the most important functions for survival of your body are fulfilled, such as breaking down food (digestion), absorbing nutrients essential for life (absorption), eliminating waste for your blood circulation (elimination) and housing the intestinal flora.
The cells of the intestinal wall look very much like a brick wall. Each cell is closely attached to other cells by tight junctions. But these are highly intelligent bricks. They keep what is foreign to the body (undigested food and microorganisms) out while simultaneously letting in whatever the body needs – nutrients from digested food. It is for this reason the intestinal wall cells must always remain intact and their tight junctions must remain tight. A missing cell or loosened junction would allow undigested food, and the good and bad bacteria inside the digestive tube and directly into the body. A discontinuation of intestinal wall cells or a loosening of the tight junctions – actual holes in the wall – leads to a condition called hyperpermeability, or leaky gut.
The Gut-Associated Lymphatic Tissue (GALT)
In an ideal world the intestinal wall cells with their tight junctions would be enough to fend off everything that is not completely digested food. However, some foreign materials or organisms may sometimes get through. This is where the body’s gut-associated-lymphatic tissue or GALT, comes into play. The GALT also makes up the largest part of the body’s entire immune system.
Our immune systems’ cells are constantly scanning the environment to detect organisms and molecules that are foreign and hostile. It accomplishes this by recognises surfaces. Everything has a surface, whether it is your own cells, a micro-organism, or a piece of food. When your immune system scans the interior surfaces of your body, it compares each to a list of approved codes, the ones it classifies as “self.” If the immune system detects a surface with a threatening code, an antigen, it releases weapons and recruits other immune-system cells to attack the foreign surface as a way to defend you and survive.
Faced with a threat the immune system launches a defence strategy that involves not only the immune cells in the gut, but also all the immune cells around the body. Now the immune system works best in certain conditions (heat, by which it creates a fever in the body is one example). But it also requires a whole set of other conditions – called inflammation. Often turned on by dysfunction in the gut, inflammation is the body’s best example of adapting and surviving. For millions, the gut is where systemic inflammation is born and from where it is sustained. Sustained systemic inflammation is what leads to many of the chronic diseases in the world today.
A GALT in a constant state of attack – which is more or less the case for everybody today – is much like having a quad muscle in constant contraction. When the cells of the GALT launch attacks, they use up invaluable resources and energy. The cells of the GALT manufacture antibodies and proliferate. They cause all kinds of chemical reactions, which cause corresponding effects in the rest of the body. Such as when mast cells produce and release histamine, which in turn causes airway obstructions, vasodilatation, mucus secretion and itchiness. And someone may fee exhausted, with no other symptom, unable to put his or her finger on what’s wrong.
The immune system in general to get rid of foreign invaders. Sneezing and coughing are attempts to get rid of airborne invaders, such as pollen or mites. So it seems logical that the immune system will try and get rid of them by any means necessary. Itching is a way the immune system tells you to scratch and get rid of something in the skin . Many people who are convinced they have seasonal allergies, get rid of their symptoms after gut repair. The pollen is till there, but after gut repair, they do not respond allergically.
The Intestinal Flora
The intestinal flora performs many important functions. They are the first things other organisms encounter in the digestive tube, and they fight to protect their territory and prevent other organisms from taking hold. In this way, the intestinal flora helps the immune system fight invaders. Even when there is threat of invasion, the intestinal flora remains hard at work, constantly stimulating the GALT. Their effect on the GALT is known as immunomodulation. One of the most fascinating functions of the intestinal flora is their ability to regulate the immune system.
The presence of the gut’s beneficial bacteria signals to the immune system that things are working well. Their presence also means that the climate in the gut is healthy. The immune system can’t directly contact the intestinal flora, but one type of immune system cell, called dentritic cells, send filaments into the digestive tube through the intestinal wall to gather information of the conditions there and look for the presence of good bacteria. This is known as “snorkelling”. The cellular activity of being constantly on the lookout for intestinal flora is what keeps the immune systems awake and alert – ready for, but not engaged in, attack. The good bacteria regulate the immune system’s baseline activity.
The intestinal flora does many other things as well. They digest part of our food for us. Certain nutrients, such as B vitamins, have to be predigested by bacteria before the body can absorb them.
A healthy gut acts like a fermentation tank inside you. Because so many people’s inner fermentation tanks are not populated with good bacteria, it is beneficial to consume fermented foods. “Fermented” really means that the food has already been digested bacteria.
The intestinal flora is also a key contributor in detoxification, ridding the body of 40 percent of the toxins in food. In this sense, they serve as a satellite liver. Put another way, if the gut didn’t; have the intestinal flora, the liver would have had to work almost twice as hard.
The importance of a healthy intestinal flora cannot be overstated. Several studies suggest that changes in the composition of gut bacteria are linked to such varied diseases as obesity, inflammatory bowel disease, asthma, mental disorders and many others.
The Gut’s Nervous System
Nerve filaments, spread throughout the gut like a net, send and received information to and from our gut neurons which coordinate, modulate, and regulate the intestinal wall cells, the GALT cells and the arteries inside the gut at the same time, continuously. In other words, the neurons in your gut orchestrate peristalsis and digestion, and modulate immunity and the hormonal system. Without them, the gut would cease to work.
If you were to isolate all the neurons that live inside your gut and clump them together, they would form a mass of neurons larger than the ones inside your head. In fact, the brain in your gut is way more active in the production of neurotransmitters than the brain in your head. Serotonin, the neurotransmitter responsible for the feeling of happiness and well-being, is primarily manufactured in the gut – 90 percent of it, in fact. On top of all this the brain in your gut helps run your intuition, hence the term “gut feeling”.
Adapted from Clean Gut by Dr. Alejandro Junger, M.D