Understanding digestion

Quality digestion cannot be overlooked and is of critical importance when discussing a healthy diet. Every part of our body and mind is dependent upon proper digestion in order to supply ourselves with the nutrients we need to function.  
Digestion is a parasympathetic process, meaning the body and mind must be in a relaxed state for proper digestion to occur.  Eating when rushed or otherwise preoccupied will impair normal digestive function and inhibit nutrient secretion.  You won’t absorb all the quality nutrition if you aren’t in a composed and relaxed state.  
How the digestive process flows:
Mouth:
Digestion begins in the mouth where the amylase enzyme begins the breakdown of carbohydrates. Thoroughly chewing makes the job much easier for the rest of the digestive system.
Stomach:
From there, the chewed food travels down the esophagus and enters the stomach where it gets mixed with pepsin and hydrochloric acid to break down the complex proteins into amino acids.  These amino acids get further broken down for absorption in the small intestines.  The ability to properly digest food in the stomach is heavily dependent upon the adequate production of hydrochloric acid (HCl)  and digestive enzymes. Overeating, excess alcohol consumption and chronic stress can all cause insufficient production of HCl inhibiting the rest of the digestive process.
Small Intestine:
Nearly all food is absorbed in the small intestine, though some, such as alcohol and refined sugars, are absorbed through the stomach.  
The small intestine is approximately 25 feet in length.  Each section is lined with special receptor sites that absorb particular foods.  Digestive enzymes (from the pancreas) and bile (from the liver) are released into the small intestine to aid in the digestion of food.  Once receptors have digested food, it’s sent through the portal vein to the liver for processing.  It then gets sent to various cells in the body through the bloodstream to be converted into energy and to rebuild/repair cells. Unwanted and/or indigestible food particles get sent to the colon to be eliminated.
Large Intestine (Colon):
The colon acts as a specialized organ for producing certain vitamins and for recycling useful water for the body.  In a healthy colon, there is a large bacterial population.  Some of these bacteria are friendly and some are not.  The friendly bacteria work to produce and process beneficial vitamins and to neutralize toxins. They also work to keep the contents of the colon moving, preventing constipation and create an unfavorable environment for the “bad” bacteria.
A diet heavy with processed foods and sugars, however, creates an environment where the unfriendly bacteria can thrive.  Poor quality and processed foods promote an overgrowth of these bad bacteria which in turn disrupts our bowel movements and makes for a toxic environment.  
Having a healthy digestive system is key to keeping the body’s defenses strong.  When the gut is healthy, it is covered in a bacterial layer of protection.  This physical barrier is the first line of defense against undigested foods, toxins, and parasites. Without this beneficial layer of defense, the gut lining is likely to be weakened or broken, allowing inflammation-causing substances to penetrate and flow into the bloodstream.  
Having the right bacterial diversity protects the intestinal lining in your body and lowers the toxicity levels within.  Your gut is exposed to all kinds of toxicity from the foods you eat and from the air we breathe.  A healthy digestive process will be able to neutralize these toxic substances.  The cell walls of beneficial bacteria are able to absorb many carcinogenic substances, rendering them inactive.  With an unhealthy digestive process, however, toxins do not get cleaned up and are likely to end up in the bloodstream, especially if one has leaky gut, causing increased toxicity in the blood and brain. This increased toxicity in the brain is speculated to be one of the contributing factors to autism, dyslexia, ADHD, and depression.