An overview of the Digestive System
THE CEPHALIC PHASE:
Did you know that digestion begins in the brain? This is called the Cephalic phase. The cephalic phase is most commonly described as the anticipation of food and results from the sight, smell, thought of food. The greater the appetite, the more intense is the stimulation.
Studies are showing that between 20 and 40 percent of the total enzyme and digestive fluids that will be needed for proper digestion are secreted during the Cephalic phase. This is huge!
What can go wrong?
Your sandwich is beige, not appealing, you are not really hungry as you have had a snack one hour ago so not really salivating.
You are not focusing on your food and eating while working. You are basically skipping this phase of digestion.
We then move on to the ORAL PHASE:
During this phase the saliva in the mouth produces an enzyme called amylase which helps to break down carbohydrates. At this stage chewing is also really important as it allows your food to get expose to more amylase and therefore avoid any additional work on the rest of your digestive tract.
What can go wrong: Not chewing your food properly, your stomach has not got any teeth so make the most of this function.
THE GASTRIC PHASE :
Your food will then reach the stomach, this large pocket can contain up to 4 litters of food and liquid. The stomach has got gastric glands which produce gastric juices.
Gastric juices mostly contains hydrochloric acid which can be very harsh and can cause heartburn when in excess. Its primary role is to sterilise our food and destroy any bacteria that may be harmful. This is a really important job!
The gastric glands will also produces pepsin. The role of pepsin is to break down protein into amino acids. These amino acids perform varied roles in your body. They’re involved in important processes such as tissue growth, energy production, immune function and nutrient absorption.
The stomach is also where Vitamin B12 is extracted from the protein in your diet and is combined with another protein produced by the stomach called intrinsic factor. Intrinsic factors are necessary for the B12 to then be absorbed into the body in the small intestine. Another really important role really!
This function not working properly can result in the development of Pernicious anaemia.
The stomach has finished its job when under the action of its contractions and its enzymes your initial food looks like a chime or porridge like substance which is now going to move into the small intestine.
What could go wrong?
You are stressed and eating on the go.
When we are stressed our body activates the sympathetic nervous system which is our fight of fly response. Studies have shown that this activation reduces the production of stomach acid. For good production of stomach acid your body needs to be in the Parasympathetic zone which is your rest and digest response.
The lack of stomach acid production can increase your risk of infections and malabsorption, and can contribute to heartburn and acid reflux. Producing enough stomach acid is key to an overall good digestive health. Our ability to produce stomach acid often diminishes as we get older.
You are taking proton pump inhibitors (PPI) which are supressing the stomach acid production.
THE INTESTINAL PHASE:
The small intestine:
In this part of the digestion, the chime (digested food) will be mixed again with pancreatic enzymes to further break down food in the small intestine.
This is also where the liver will bile to assist in the digestion of fats. The pancreas also produces the hormone insulin and secretes it into the bloodstream, where it regulates the body's glucose or sugar level.
This is where the incredibly important nutrients and vitamins in your food is being absorbed and cross the epithelial barrier to gain access to the blood stream and the lymphatic system.
What can go wrong?
You are not producing enough digestive enzymes to assimilate your food, your liver is not producing enough bile acid to help with fat digestion. This can lead to bloating, tiredness, indigestion, fat soluble vitamins not being absorbed properly.
The small intestine can be where you have what is called intestinal hypermeability due to inflammation of the gut lining. That could happen when tight junctions in the gut, which control what passes through the lining of the small intestine, don't work properly. As a result some unwanted substances, food particles or inflammatory Lipopolysaccharides or endotoxins can leak into the bloodstream and cause inflammation
The large intestine or large bowel:
Whatever is left from the digestion in the stomach and the small intestine, mostly water, plant fibre and certain types of protein will end up in the large intestine.
Its function is to absorb water from the remaining indigestible food matter and then pass the useless food waste material or stool from the body.
The large intestine is also home of your microbiome. The microbes will ferment/ fed on insoluble plant fibre and produce short chain fatty acids. For instance Butyrate is the main source of fuel for your colon and may play a key role in the prevention of colon cancer.
These Short chain fatty acids are anti-inflammatory compounds and crucial for the function of our organism.
By fermenting fibre gut bacteria will also play a role in the production of vitamins such as vitamin K responsible for blood coagulation as well as most water soluble B vitamins such as folate.
Also did you know that up to 90 % of the serotonin produced in the body is found in the gut? This neurotransmitter is responsible for regulating appetite, mood sleep and bowel movement?
What could go wrong?
You do not eat enough fibre and your bacteria are starving, this could leave space for pathogenic species of bacteria to grow and thrive.
You have an imbalance in your beneficial bacteria and you are unable to produce key minerals, vitamins and neurotransmitters affecting your moods, energy level and ability to lose weight and overall wellbeing.