Most people consider the gastro-intestinal system merely a tube through which food goes in and waste products pass out, give or take a few enzymes and digestive proteins here and there to help the process of absorption of nutrients. But it turns out the gut is one of the most important organs in the body in terms of brain function as well as immunity.

There is still so much that scientists are learning all the time, and I must admit I still feel a bit overwhelmed by all the detail. Unfortunately there are also conflicting stories about the condition termed leaky gut and the causes and influence this condition has on the functioning of the body. I will attempt to negotiate through the maze of opinions to give you a rational perspective.

What has the gut to do with lifestyle medicine? A great deal. Lifestyle medicine seeks to combat poor lifestyle choices responsible for conditions such as obesity, diabetes, cardio-vascular disease, auto-immune diseases, dementia and cancer. The gut is the conduit through which many of those diseases are caused, and the health of the gut has much to do with how those diseases develop.

What we will do today is give a brief anatomy and physiology lesson about the gastro-intestinal tract. Next time we will delve into some of the history of how diet became such an important aspect of healing of the ravages of modern living. Thereafter we will deal with various aspects of how to heal the gut, and conditions that affect our gut health.

Anatomy:

I believe most of us in primary school learned the rudiments of the gastro-intestinal tract (GIT). Starting at the lips and mouth, with teeth, tongue and taste buds, to salivary glands, oro-pharynx, oesophagus, stomach, small intestine (consisting of duodenum, jejunum and ileum), appendix, colon (consisting of caecum, ascending, transverse, descending and sigmoid colon), rectum and anus. Also part of the gastro-intestinal system are the liver and biliary system (gall bladder and bile ducts) and the pancreas.

As in most parts of natural science, deeper study has demonstrated immense complexity of these structures both in anatomical structure as well as in biochemical function. Our scientific forefathers had such a simplistic perception of how things worked. From that perspective it was not too difficult for them to say that these organs and functions arose through slow processes of trial and error as random events. However any honest student of anatomy and physiology today would have to take an enormous leap of faith (or dogma) to convincingly claim that the intricate design and complex interactions responsible for normal healthy life could possibly have arisen randomly.

As I read the research about all the complex derangements taking place in the body as a result of Covid-19 infection, many of these cytokines and fancy named proteins were not even imagined when I did physiology 50 years back. Even when I did my primary examination at the beginning of my specialty 30 years ago, so much has knowledge increased about the highly sophisticated and interconnected physiology of the various organs of the human body.

A young engineering student would be overwhelmed with the complexity and sophistication of the design and functioning of a Boeing 777. And yet even a single cell in the human body makes the complexity and design of that amazing jet pale into deep insignificance.

Physiology

Our primary school physiology lesson on the GIT started with the taste buds the ability to perceive sour, sweet, bitter and salty. Now there is a new taste called umami, as we find in savoury broths and proteins and monosodium glutamate. But actually the functioning of our GIT starts even before the lips our eyes and noses can start the process of digestion getting the cravings and the digestive juices going. Who has not had salivary glands secrete at the thought of a sour lemon; or the aroma of freshly baked bread stimulate desire for a slice.

Chewing of food and mixing it with saliva, with some of those enzymes that already begin to break down complex carbohydrates starts the digestion process. Smoothies and juicing are the craze, and although there are many advantages in terms of saving time, taking your time to chew the food is part of the relaxation that goes into helping your digestive process work more efficiently, apart from the benefit of the social event of a meal with family or friends. (By the way juicing removes much of the fibre which we will learn later is vital for proper health of the intestinal flora. Smoothies do retain the fibre).

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The strong hydrochloric acid of the stomach is antiseptic killing bacteria, But it has other benefits as well. It helps with the breakdown of foods, in particular protein by activating the enzyme pepsin. It also helps with the absorption of vitamins and minerals such as B12, iron, calcium and magnesium. It prompts the release of digestive enzymes and bile from the pancreas and gall bladder respectively. The stomach also acts as a temporary store of ingested foods which are gradually released into the duodenum. Cells lining the stomach wall secrete mucus which protects the delicate epithelial cells from damage from the strong acid. The integrity of these lining cells is important to prevent gastritis and ulcers.

The small intestine is responsible for breakdown and absorption of nutrients. Multiple enzymes are secreted from the pancreas to help with protein digestion, and bile salts come from the liver via the gall bladder to help with digestion of fats. Carbohydrates are further broken down into simple sugars. The surface area of the small intestine is greatly increased by the presence of folds called villi, and in turn these villi are covered with hundreds of microvilli which are well endowed with capillaries. The small intestine is lined with just a single layer of cells across which sugars and fats easily cross, and through which proteins and some carbohydrates, minerals and vitamins are actively transported.

The integrity of this single layer of cells is vital to prevent harmful micro-organisms as well as to keep antigenic proteins and toxins out of the body. Within the wall of the small intestine are lymphatic tissues, (called Peyers patches) similar to the tonsils and adenoids in the wall of the oropharynx and nasopharynx. These lymph glands provide the first warning of harmful invaders to the body and set the immune system into action to fight potential dangers.

Here is an interesting article detailing the complex immune systems at play in the intestinal wall. As you will discover from this article there is a delicate balance between healthy protection and over-reaction with excess inflammation of the bowels. Enter the gut microflora. I will not go into details at this stage, as there is so much information it will take a special article to just cover the broad picture of what the microflora is all about.

One last physiological concept the quantity of fibre in the intestinal contents has a direct effect on the bowel passage time. There are two types of fibre insoluble fibre such as wheat bran, and water soluble fibre such as pectin found in fruits and vegetables, and oats fibre. The latter is digested by the bowel flora into butyric and propionic acid which have beneficial effects on bowel function. Recommendations are around 30 gm of fibre per person per day for a healthy gut.

I trust that you will have a peaceful week, in spite of the stresses of either going back to work for those who can, or the stresses of not being able to go back to work for those who cant. Whatever you do, remember to implement the preventive measures of social distancing, washing hands frequently or using hand sanitiser, avoiding touching your eyes, nose and mouth with unwashed hands, and now wearing of face masks in public places. (I see many people fiddling with their face masks which defeats the purpose. Try to find or make a mask that is comfortable to wear and fits well, to avoid touching it frequently.)

Kind regards,

Dave Glass

Dr David Glass graduated from UCT in 1975. He spent the next 12 years working at a mission hospital in Lesotho, where much of his work involved health education and interventions to improve health, aside from the normal busy clinical work of an under-resourced mission hospital.

He returned to UCT in 1990 to specialise in obstetrics/gynaecology and then moved to the South Coast where he had the privilege of, amongst other things, ushering 7000 babies into the world. He no longer delivers babies but is still very clinically active in gynaecology.

An old passion, preventive health care, has now replaced the obstetrics side of his work. He is eager to share insights he has gathered over the years on how to prevent and reverse so many of the modern scourges of lifestyle obesity, diabetes, ischaemic heart disease, high blood pressure, arthritis, common cancers, etc.

He is a family man, with a supportive wife, and two grown children, and four beautiful grandchildren. His hobbies include walking, cycling, vegetable gardening, bird-watching, travelling and writing. He is active in community health outreach and deeply involved in church activities. He enjoys teaching and sharing information.

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Turning the Tide: Digest these facts about your gut - South Coast Herald