Digestion begins with the thought, sight and smell of food. These senses trigger appetite and oral and gastric secretions, preparing the upper digestive tract for food.
The next stage is chewing your food, breaking it down into smaller pieces and mixing it with saliva. Our saliva contains enzymes, minerals and antibacterial substances. The enzyme lipase helps to break down fats and amylase breaks down carbohydrates. This is where protein digestion starts.
Now on to the oesophagus. This is the gateway for food which travels through the sphincter and into the stomach. Loss of sphincter tone is one of the major causes of reflux, not an issue with acid as many people think.
Then we have the stomach. The inner most layer of the stomach is made up of parietal cells which secrete hydrochloric acid, chief cells which produce pepsinogen and mucous-secreting cells. Can you believe that around one to three litres of gastric fluid containing hydrochloric acid, digestive enzymes and binding products is secreted in a day? All of this helps to break down our food when it reaches the stomach. The main role of the stomach is to break down protein, convert enzymes, solubilise nutrients and convert iron into its bioavailable state. Water, iodine, copper, fluoride and molybdenum are all also absorbed in the stomach.
The small intestine is up next. This is where the MOST of our digestion occurs. A series of finger-like projections, called villi, are present on the mucous membranes of the small intestine, increasing the surface area where ABSORPTION occurs. Carbohydrate digestion is completed here as more enzymes are released by the pancreas. Protein is also further digested and fat digestion continues.
The small intestine is so important as this is where substances are absorbed including essential vitamins, minerals and amino acids. If people have upper-digestive issues, constant inflammation or damage occurring to the small intestine, they are at risk of further issues throughout the whole body.
The small intestine can get an overgrowth of bacteria which is called small intestinal bacterial overgrowth (SIBO). This is highly correlated to irritable bowel syndrome (IBS), a disorder causing abdominal pain, bloating, diarrhoea and constipation. Many people who are diagnosed with IBS actually have SIBO. There are numerous causes of SIBO including medication use, infections, stress and poor diet to name a few.
One of the most important elements within the small intestine is secretory IgA (SIgA). SIgA plays an important role in mucosal immunity, the part of our immune system that separates the outside environment from the inside of the body including digestive and respiratory tracts. An important activity of mucosal surfaces (SIgA) is that they serve as a first line of defence to repel pathogenic microorganisms and provide a finely tuned balance to guarantee controlled survival of essential commensal bacteria.
SIgA may also have beneficial effects in overall immunity by reducing inflammation within the digestive tract. Microbiome testing can identify if levels of SlgA have been affected (commonly by medication use, poor diet, high stress, inactivity, infections, high gut inflammation and poor gut immunity) and are contributing to major gut symptoms. Prolonged low SIgA levels are not ideal as this creates an environment within the gut where unwanted bacteria and infections can thrive, creating an imbalance in the gut microbial community associated with disease. When we can identify low SlgA levels, we can address it through naturopathic treatment, changing the health of people’s gut.
Written by Karly Raven BHSc
Want to know more about the digestive system?
The above is an excerpt (modified) from Nourish Your Gut, the latest ebook from naturopath and gut health guru Karly launching on 29 October.
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