The immune system- The Digestive process.
In my book, Just Food for Health, the chapter on the digestive system is nine A4 pages long (there are a few illustrations). You are used to seeing long posts from me which is why I split the topic over several posts last week. About this time last year I wrote this short story to describe the passage of a very common and tasty snack that many of us enjoy. Usually with only one thing in mind. The taste.. However, perhaps after following this chicken sandwich through your digestive tract you might think about it in a different way. For those who read this last year.. apologies but I wanted to link last week’s digestive system series and the previous immune system together.
Firstly, though a little about antibiotics. Most of the stories in the media are about the concerns of scientists and doctors that we are fast running out of effective antibiotics to kill the many strains of bacteria that threaten our health.
If human DNA only mutates every 10,000 years or so, they are outstripped by ‘Formula 1‘ bacteria. They are mutating in a heartbeat to survive and this is where the problem lies with antibiotics. We have over prescribed them in the last 50 years or so, pumped them through the food chain resulting in damage to our immune systems and we have created a group of superbugs that don’t care what you throw at them.
Our immune system is our own personal health insurance and we need to make sure that it is boosted so that it can handle the minor bacterial infections we will all have from time to time and only have antibiotics if our system cannot overcome the problem itself.
The purpose of this post is to illustrate how the food that we put in our mouths is critical to the efficiency of our Immune System. Without the right ingredients that have to be processed at every stage of digestion, there would be no defence mechanism in place and we would die. Therefore you really need to think of these two major operating systems of the body as working in tandem.
Our body is pretty amazing but it is not a magician. You do not eat a meal and are suddenly flooded with vitamins and minerals. It is necessary for the food to go through a complex process before its nutrients can be utilised to combat bacteria and provide us with energy.
For that task we need enzymes and other ingredients produced by our organs. For the purpose of this post I am going to use a sandwich that many of us might eat and then forget about. What happens to it after the juicy chicken and tangy mayo has left our mouth is not our concern surely? But it is!
One of the most complex systems in our body is already at work having begun the process the moment you started to chew the first mouthful of the sandwich.
You take your first bite of a wholegrain sandwich with chicken and salad, a bit of butter and a smidgen salt and mayonnaise (lovely)- in the meantime your teeth, tongue and salivary glands that produce the first phase of enzymes begin the digestive process before passing the food (properly chewed is helpful) into the pharynx at the back of the throat. For example amylase produced by the salivary glands converts the bread in the sandwich into pairs of sugars, or dissacharides.
The food then passes into the oesophagus through to the stomach where hydrochloric acid modifies pepsinogen, secreted by the stomach lining to form an enzyme called pepsin. Pepsin breaks down the chicken into smaller units called polypeptides and lipase will break down any fatty globules into glycerol and fatty acids. The acid in the stomach will also kill as much harmful bacteria as possible (not only in the food itself but passed on from the hands that made it and the board it was made on). The end result is a highly acidic liquid that is passed into the duodenum.
The duodenum will secrete a mucus in response to two hormones (secretin and pancreozymin) that are released to neutralise the acidic liquid that was your chicken sandwich. Bile is also passed into the duodenum either directly from the liver or from the gallbladder where it has been stored.
Bile is a complex fluid containing water, electrolytes and organic molecules including bile acids, cholesterol, phospholipids and bilirubin essential for the digestion of fats and their absorption along with fat-soluble vitamins as they pass through the small intestine. The bile has also picked up the waste products that have been accumulating in the liver so that they can be passed through the colon for elimination.
Referring back to my cholesterol blogs – https://smorgasbordinvitation.wordpress.com/cholesterol-2015/ – this is when total levels are affected by the efficiency of the bile process. Cholesterol not only comes from food but is also manufactured in the liver. It is virtually insoluble in most fluids except for bile where the acids and fats such as lecithin do the job. If this process is not effective cholesterol can collect into stones that block the ducts and cause problems with the digestion of fat. Bile levels in the body are lowest after fasting which is why you have a cholesterol test at least 12 hours after your last meal.
By the time the liquid sandwich reaches the duodenum the particles within it are already very small, however they need to be smaller still before they pass into the ileum, where the final chemical processing will take place. The enzymes that have joined the mix from the pancreas and amylase will break down the food even further into peptides and maltose which is a disaccharide sugar.7. The small intestine is lined by millions of villi, tiny hair like projections which each contain a capillary and a tiny branch of the lymphatic system called a lacteal (yesterday’s blog). More enzymes maltase, sucrase and lactase are produced to facilitate the absorption of the smaller particles through the villi – including breaking down the sugar pairs into single sugars called monosaccharides which pass through easily.
The glycerol, fatty acids and the now dissolved vitamins are sucked up into the lymphatic system through the lacteal and into the bloodstream. Other nutrients such as amino acids, sugars and minerals are absorbed into the capillary in the villi which connects directly to the hepatic portal vein and the liver. It is here, in the liver that certain nutrients will be extracted and stored for later use whilst others are passed onto the body.
The carbohydrate in the sandwich we have eaten has been broken down into first pairs of sugars and then into single sugar molecules and have passed through the villi into the liver. Glucose provides our energy and the liver will determine current levels in our system, how much glucose to convert to glycogen to store and how much to release directly into the bloodstream as long term imbalance can cause diabetes.
Once all the nutrients have been extracted and passed into the bloodstream, lymphatic system or liver, any insoluble and undigested food moves into the large intestine. Any water and salt remaining in the mixture is absorbed into the lining of the intestine and the remainder mixes with all the other waste products produced by the body such as bacteria and dead cells – it is then pack and pressed and stored for excretion.
So there goes the last of your chicken sandwich. I hope it puts a different perspective on the food that you are putting into your mouth – it also is important to remember that if you have a white diet, white grains, fats and sugars, you are giving your body a great deal less to work with and your body and immune system will struggle to get what it needs to be healthy.
The only foods that provide our digestive system with the raw ingredients to maintain and boost our immune systems are natural, unprocessed vegetables, fruit, protein, wholegrain carbohydrates and healty fats.
If 80% of the time you are consuming these foods cooked from scratch then 20% of the time eating foods that have are not as healthy is not a problem.
Most of us have access to an amazing variety of fresh foods but stay firmly fixed on a handful. We need a really wide variety of food to obtain all the nutrients we need for our immune system and this shopping list might help you out.
©sallygeorginacronin Just Food For Health 2008
Thanks for dropping by and please feel free to share.. your feedback is always very welcome.. Sally