Giulia Enders is a German writer and a medical fellow (Frankfurt in Mannheim 1990) whose first book GUT (original title in German: « Darm mit Charme. Alles über ein unterschätztes Organ ») sold over 1 million copies in Germany, was translated to many languages and sold over 400 000 copies in France. The young lady, as her studies progress, will certainly become a brilliant gastro-enterologist. She was known for a talk called « Charming bowels », which led her to win many prizes. And that’s the reason why she received an offer to write GUT. Woody Allen would have called this book « Everything You Always Wanted to Know About Gut (but were ashamed to ask) ». I read it in English since my daughter bought it that way and I was quite curious since people were talking about the book around me.
The book was published in Germany in March 2014 with cute and naïve drawings from Ender’s sister, Jill, a talented graphic designer. GUT explains in a simple and humourous way the important functions of our gastrointestinal tract and its relationship with the immune system.
We’ll be learning so many items about this part of the body… And believe it or not, it is often outright funny. For instance, when she explains the right way to poo. Because the way we do it is anti physiological: being seated, we close the channel with a lasso ( a muscle) and our sphincters must expend much more energy to go through; if the lasso muscle relaxes, the kink straightens (the road ahead is straight, the faeces are free to « step on the gas »). One must know that squatting has been the natural pooing position for humans since time immemorial because the modern sitting toilet has existed only since indoor sanitation became common, in the late XVIIIth century. Japanese researchers found that squatting does indeed lead to a nice, straight intestinal tract, allowing for a direct, easy exit.
FACTS ABOUT FAECES : faeces are 3/4 WATER. We lose around 100 ml of fluid a day. During a passage through our digestive system, some 9,8 litres are re-absorbed. What we deliver into the toilet bowl is the result of an absolute maximum level of efficiency. A THIRD of solid components are BACTERIA. They are gut flora that have ended their careers in the digestive business and are ready to retire from the workplace. Another third is made up of indigestible vegetable fibre (from 100 to 500 grams per day). And the remaining third is a mixed bag of substances that the body wants to get rid of : remains of medicines, food colorants, cholesterol.
I learnt an amazing fact about saliva : when we are asleep we produce very little saliva. That’s good news for those who tend to drool onto their pillow – if they produced the full daytime quota of one to one-and-a- half litres during the night, too, the results would not be very pleasant. The fact that we produce so little saliva at night explains why many people have bad breath or a sore throat in the morning. Eight hours of scarce salivation mean one thing for the microbes in our mouth : party time ! Brazen bacteria are no longer kept in check, and the mucous membranes in our mouth and throat miss their sprinkler system.
An astonishing point is to learn that the root of the tongue is made of immune tissue, nodules called lingual tonsils whose job is to investigate everything we swallow. Inside the nodule an army of immune cells waits to receive training in how to deal with foreign substances invading us from the outside world. The role of the tonsils is well known but people do not know that removing the tonsils before the age of seven can lead to an increased risk of obesity and the reason why, well, hasn’t been figured out yet by doctors.
The histological structure of the gut is amazing : the small intestine is 7 meters in length; each square millimeter of the surface contains some thirty tiny finger-like projections calles villi swimming in the chyme (partly digested food). Under the microscope little villi look like large waves made out of cells and everyone of those cells is covered with protusions called microvilli. And listen to this…if all this – the folds, the villi and the microvilli were ironed out to a smooth surface, our gut would have to be some seven kilometres in length. In total, the surface area of our digestive system is about one hundred times greater than the area of our skin. The small intestine is a very clean laboratory : an hour after digestion a cleaning-up process begins, called « migrating motor complex » that scientists call « the little housekeeper »; when the stomach and the small intestine are empty, the cost is clear for the housekeeper to do its work. Constant snacking means there is no time for cleaning and that’s why nutritional scientists recommend we leave five hours between meals
Our large intestine takes care of things that cannot be absorbed in the small intestine; and the large intestine is the home of most our bacteria, which can break down the last nutritious substances for us. People are slowly beginning to realise that the vast majority of bacteria are harmless and helpful. Our gut’s microbiome can weigh up to 2 kilos and contains about 100 trillion bacteria. One gram of faeces contains more bacteria than there are people on Earth. This community of microbes crack indigestible foodstuffs, supply the gut with energy, manufacture vitamins, break down toxins and medications, and train our immune system. Bacteria are tiny factories. Bacteria make up more than 90 per cent of the population of our gut. Taken together our gut bacteria have 150 times more genes than a human being; this massive collection of genes is called a biome.
The idea that the bacteria in our gut might influence our overall metabolism, and therefore our weight, is only a couple of years old. Very few gut bacteria reside in the small intestine, where we break down our food for ourselves and absorb the nutrients from it. The highest concentration of bacteria is found where the digestive process is almost finished. The further you travel from the small intestine towards the final exit from the gut, the more bacteria you will find per square centimeter of gut membrane.
An interesting point of view is about food intolerance, increasing in Western countries. Food intolerance may in fact be nothing more than the reaction of a healthy body as it tries to adapt within a single generation to a food situation that was completely unknown during the millions of years of our evolution.
Vomiting is a piece of art. Because it is not a stomach stumble : it happens according to a precise plan. Millions of tiny receptors test our stomach contents, examine our blood, and process impressions from the brain. The brain evaluates this information and depending on how many alarms bells are ringing, it makes a decision : to barf or not to barf. The brain transmits its decision to selected muscle groups, and they get down to work.
About constipation, especially while travelling. The point is the gut is a creature of habit. The nerves of the gut remember what kind of food we prefer, and at what time we prefer to eat it. They know how much we move around and how much water we drink. They know whether it is day or night, and what time we usually go to the toilet. All the changes when travelling get noticed by the nerves of the gut and they are waiting for a signal that everything is normal in order to start work again. It doesn’t help that travelers dislike going to unfamiliar WC, and are not relaxed enough to finish the work.
So many interesting things in this book, so many things to learn from our unloved gut. It’s not fair. The brilliant digestive system and the poo function should be re-assessed with sympathy and recognition. God save the gut !
GUT, Scribe 2016, ISBN 978-1-925228-60-1