Ever wonder what happens after you swallow your food? Do you wonder WHY it’s so important to eat certain foods over others? Maybe you have digestion issues and don’t understand why? Hopefully I can clear some of this up for you.This article started with my own research to understand some of my own digestion problems over the years.
Here we will take a look into some aspects of digestion. Like any other subject, the more you look at it, the greater detail you see, and the more questions arise, not to mention, the number of unexplainable anomalies that come up.
Let’s start with what happens before you even put that first bite of food into your mouth.
The Brain
Believe it or not but your Brain starts your digestion. Yes, chemical digestion does begin in the stomach but before it gets there, many signals are sent from the brain to start the process. When you sit down and begin to eat, your brain has already signaled to the stomach to start producing gastric juices. Too many people sit down and shovel their meals in like they haven’t eaten in days. The food hasn’t even reached their stomachs yet and the digestion process has already been disrupted. It’s important to sit down, absorb the aroma, take your time eating and chew your food properly. Chewing food properly, so it can be broken down mechanically, is frequently neglected. This means the enzymes in the saliva do not get a chance to work on the food and the stomach has to do more work. Proper digestion becomes very difficult if we are on the go all the time as stress actually shuts down the production of gastric juices.
The Mouth
When we see, smell, taste, or even imagine a delicious meal, our salivary glands begin producing saliva. This flow of saliva is set in motion by a brain reflex that’s triggered when we sense food or think about eating. In response to this, the brain sends impulses through the nerves that control the salivary glands telling them to prepare for a meal.
Salivary glands secrete a fluid that contains water, electrolytes, mucus and enzymes. Such a simple task plays an important role:
Lubrication: The mucus in the saliva is very effective in binding chewed food into a slippery substance that can easily slide through the esophagus without damage.
Solubilizes dry food: If food isn’t solubilized you will never taste it.
Oral Hygiene: Because your mouth is constantly being flushed with saliva, it carries away food debris and keeps the mouth relatively clean. Ever wonder why you have skank breath in the morning? This is because the flow of saliva decreases during sleep which allows a build of bacteria in the mouth.
Starch Digestion: An enzyme called Amylase is secreted in saliva. This enzyme begins the digestion of starch into maltose. You may have heard that you should not drink a lot of water when eating. This is due to the water flushing away the enzymes and gastric juices.
The Stomach
Once the stomach senses food, it secretes the hormone gastrin into the blood. Gastrin affects digestion in two ways. First it stimulates the secretion of HCL. Secondly it causes contraction of the muscles responsible for stomach motility. The gastric secretions in the stomach consist of protective mucus, pepsinogen, and HCl. Pepsin is the enzyme that digests food proteins.
The stomach’s job is to start the breakdown of proteins with pepsin. Built of chains of Amino Acids, proteins must be broken down in order to be rebuilt in the liver. No proteins that we eat are used as they are and all proteins are broken into amino acids.
Of all usable substances, proteins take the longest, and are the hardest to digest. The entire Stomach exists simply to initiate this breakdown so that our friendly bacteria in the intestines can take the amino acids they need, and leave us what we need.
Food will remain in the stomach for anything from 10 minutes to three hours, depending upon its protein content. This is why it’s so important to eat every 3 hours so that we supply enough fuel for our daily activities and exercise.
All the protein not acted upon in this stage will go on to putrefy in the bowel over the next few hours, so food must not be hurried through this stage by overeating.
HCL (hydrochloric acid) plays an important role in the total digestive picture. It converts pepsinogen to pepsin which induces protein digestion. It keeps the stomach sterile against parasites, bacteria and viruses. It prevents bacterial or fungal overgrowth of the small intestine. It stimulates the stream of bile (see topic: Liver) and pancreatic enzymes and facilitates the absorption of nutrients.
Nowadays people tend to have too low of an acidic level in their stomachs to induce proper digestion. With lowered HCL the normal sequence of digestion and nutrient absorption is disrupted. HCL is required for the best absorption of folic acid, ascorbic acid, beta carotene, iron, calcium, magnesium, and zinc.
Next your pre-digested food makes it way to the small intestine for digestion.
The Liver
The liver is the largest gland and the largest organ in the body weighing at approximately 3.5 pounds. It performs an amazingly large number of tasks that impact all body systems. I will point out a few functions of the liver but mainly for the sake of understanding what this astonishing organ/gland can do.
The liver is responsible for manufacturing proteins to help maintain the volume of blood and blood clotting factors. It synthesizes, stores, and metabolizes fats, including fatty acids and cholesterol. It metabolizes and stores carbohydrates, which are used as the source of energy for red blood cells and the brain and it detoxifies by secreting toxins such as drugs and alcohol. This is only a few functions performed by the liver but to stay in scope of this article will get back to digestion.
The liver is responsible to create and secrete bile that contains bile acids to aid in the absorption of fats and the fat-soluble vitamins.
Bile is a fluid containing water, electrolytes and a slew of molecules including bile acids, cholesterol, phophlipids and bilirubin. Cholesterol is required for digestion. The body uses cholesterol to synthesize bile acids, which are important for the digestion of fats. Fats are generally water resistant, and insoluble. For the body to utilize them it must first make them water-soluble. This is done by emulsification which is one of the attributes of bile.
Many waste products, such as bilirubin, are eliminated by secretion into bile and elimination in feces. Little fact: Bilirubin is what makes your stool brown.
The Pancreas
Pancreatic juice is composed of two things critical for proper digestion: digestive enzymes and bicarbonate.
The pancreas secretes an amazing amount of enzymes that collectively have the capacity to reduce all digestible macro-molecules into forms that are capable of being absorbed. There are three major groups of enzymes are critical to efficient digestion:
Proteases
Proteins are first broken down by the stomach with pepsin but the bulk of protein digestion is due to the pancreatic proteases. Several proteases are synthesized in the pancreas and secreted into the small intestine.
Lipase
A major component of dietary fat is triglycerides. A triglyceride particle cannot be absorbed and it must first be digested into a 2-monoglyceride and two free fatty acids. The enzyme that performs this is lipase. Sufficient quantities of bile salts must also be present in the intestine in order for lipase to efficiently digest dietary triglyceride and for the resulting fatty acids and monoglycerides to be absorbed. This means that normal digestion and absorption of dietary fat is critically dependent on secretions from both the pancreas and liver.
Amylase
Amylase is the enzyme that changes starch to. The major source of amylase is pancreatic secretions, although amylase is also present in saliva as you may recall.
Bicarbonate is a base and critical to neutralizing the acid coming into the small intestine from the stomach. This neutralizes the acidity of the fluid arriving from the stomach raising its pH to about 8.
The Small Intestine
After leaving the stomach the liquidated food (chime) enters the small intestine. Your small intestine is a 20-25 foot tube that is coiled up in your abdomen. There are three distinct portions, each of which is highly specialized for different digestive functions.
Duodenum
This is the first section of the small intestine. The duodenum is the major portion of the small intestine where chemical digestion takes place with the use of enzymes. The small intestine secretes several enzymes to break down the chime into usuable nutrients.
Sucrase: breaks sucrose down to glucose and fructose
Maltase: breaks maltose down to glucose
Lactase: breaks down lactose into glucose and galactose
Petidase: splits peptides from protein into amino acids
Lipase: breaks down fat into glycerol and fatty acids
The duodenum receives bile from the liver and gallbladder, to decrease the surface tension between the large fat globules and water. The bile breaks them into smaller globules that can be acted upon by lipase, amylase, sodium bicarbonate and several other enzymes which are received from the pancreas.
Jejunum
This next section of the small intestine has a lining which is specialized in the absorption of carbohydrates and proteins. This lining consists of finger like projections called Villi. The proteins have been broken down in the stomach by enzymes called pepsin and acid into amino acids. The carbohydrates are broken down in the duodenum by enzymes from the pancreas and liver into sugars. Fats are broken down in the duodenum by lipase from the pancreas into fatty acids. Amino acid, sugar, fatty acid particles, vitamins, minerals, electrolytes and water are all now small enough to soak into the villi of the jejunum and be transported into the blood stream. The blood takes all these nutrients to all the other parts of the body to provide fuel to do their jobs.
Ileum
The third portion of the small intestine is called the ileum. It is responsible for the very selective absorption of some significant nutrients. This includes vitamin B-12, vitamins dissolved in fatty liquids, electrolytes; bile salts and water which soak through the walls and into the blood stream By the end of the small intestine, the majority of the nutrients have been absorbed. Where the ileum joins the large intestine is a valve which prevents the back flow of materials into the small intestine. By the time material reaches this point, it has a rather pasty consistency. This material is now mostly waste products and water, and is referred to as liquid stool.
Large Intestine
The large intestine is approximately five feet long and is equipped with sensitive nerves and muscles in the wall lining. Their function is to create wave-like motions known as peristaltic waves; these propel the contents of the colon from the celium to the rectum for eventual evacuation.
Besides the formation of peristaltic waves, the first half of the large intestines has two very important functions. First, it must extract the residue and any available nutritional material unused by the small intestine. By first mixing the material, it then transfers and remained saved nutrition through its walls where it is collected by blood vessels. The bloodstream in turn carries this collected nutrition to the liver for processing. Second, it gathers intestinal flora from the glands in its walls needed to lubricate the colon.
Healthy Flora
Bacteria in your colon are referred to by many different names such as probiotics, good or bad bacteria, acidophilus, disbiosis etc. Your colon has both good and bad bacteria. The good bacteria maintain the health of your colon by keeping the bad bacteria from multiplying and reducing constipation and bloating.Unfortunately most people have bad bacteria as the dominant condition in their colon. When the bad guys take over the good guys we need supplementation of daily probiotics to keep a happy colon ?
Digestive Problems
If you have any problems with any step of digestion there are ways that you can help the process.
First and foremost, understand that taking the time to eat your food, chewing properly and not rushing is the first step in proper digestion.
Hydrochloric Acid
HCl plays an important part in the initial digestive step in the stomach. If there is a deficiency then this can result in digestive problems all the way through the digestive tract. Remember your stomach need to be acidic to begin digestion. Many HCL supplements will contain Pepsin to aid in the breakdown process of proteins into peptides.
Some of the symptoms of low HCL are:
Dryness of the mouth
Heartburn
Indigestion
Excessive gas
Bloating or distention after eating
Diarrhea or constipation
Fatigue
Multiple food sensitivities
Abnormal intestinal flora
Candida
Intestinal parasites
Iron deficiency
Post-adolescent acne
Undigested food in the stool
Weak, peeling and cracked fingernails
Digestive Enzymes
The primary digestive enzymes are proteases to digest proteins, amylases to digest carbohydrates, and lipases to digest fats. These enzymes function as a catalyst to help break down food. In the stomach, hydrochloric acid activates pepsinogen to pepsin, which breaks down protein, and gastric lipase begins the on the fats. Without proper enzyme production, the body has a difficult time digesting food, often resulting in a variety of chronic disorders. You can purchase digestive enzymes with the 3 major enzymes required: Amylase, Protease, and Lipase
Some of the symptoms of digestive enzyme deficiency:
Anxiety
Low blood sugar
Kidney problems
Back problems
Candida
Bacterial and viral infections
Constipation
Parasites
Insomnia
Water retention
High cholesterol
Obesity
Diarrhea
Fatigue
Allergies
PMS
Skin problems
Gas
Bloating
IBS
Probiotics
If you get nothing more out of this article other than to get yourself some probiotics than I’ll be happy. Probiotics are by far most important component to proper digestion. Not only do probiotics make a colon happy but research is showing that people that take daily probiotics have healthier immune systems. They are also showing that probiotics could be used in place of antibiotics in minor health issues such as colds, skin rashes and stomach flu.
A study published in the journal Neurogastroenterol and Motility (Kim HJ, Vazquez Roque MI, Camilleri M, Stephens D, Burton DD, Baxter K, Thomforde G, Zinsmeister AR) looked at patients with IBS and significant symptoms of bloating. Forty-eight patients were used for the study, with the test group receiving high dose probiotic treatment twice a day, and the control group receiving a placebo. The patients in the probiotic group reported reduced levels of flatulence, and also slower colonic transit.
Another controlled trial, published in the European Journal of Gastroenterology and Hepatology (Niedzielin K, Kordecki H, Birkenfeld B), studied the effect of the probiotic Lactobacillus plantarum 299V. Twenty patients received a liquid suspension of the probiotics over a period of four weeks, and twenty patients received a placebo. All 20 patients who had been treated with the probiotic reported a reduction in their abdominal pain, compared to 11 patients in the placebo group. Six out of 10 constipation-predominant patients reported more frequent bowel movements in the probiotic group, compared to two of 11 constipation-predominant patients in the placebo group. In IBS symptoms overall, 95% of patients who had taken the probiotic saw improvements, compared to 15% in the placebo group.
A randomized, controlled trial was conducted in Australia with 56 infants (with an average age of 11 months) suffering from atopic dermatitis that varied from moderate to severe. The infants were either given probiotics or placebo twice a day for eight weeks. Tests were carried out to determine if the probiotics influenced the children’s immune response to eczema. The toddlers receiving the probiotics showed a significant improvement in markers for immune response and also improved clinically. The authors concluded that probiotics can stimulate immune function in children with atopic dermatitis.
In another study carried out in Germany with 479 healthy adults, researchers found that the group taking probiotics were sick with colds for significantly fewer days, had fever for shorter periods and suffered less severe symptoms. The researchers concluded that the use of probiotics can stimulate the immune system to resist infections such as the common cold.
Symptoms of bad bacteria taken over:
Infectious diarrhea
Irritable bowel syndrome
Inflammatory bowel disease like Chronics.
Bacterium that causes most ulcers and many types of chronic stomach inflammation
Tooth decay and periodontal disease
Vaginal infections
Stomach and respiratory infections
Skin infections
Parasites
Conclusion
Understanding the digestion process is not a simple task but an important one. I truly believe that the majority of health problems out there are due to poor digestive systems. Keeping your digestive system happy, healthy and active will keep your overall health up to par. Hopefully I’ve been able to clear some of this up for you and if you have any further questions let me know.
References:
Arbor Clinical Nutrition Updates (2006). Probiotics, immunity & allergy. Issue 246, April 2006; Arbor Clinical Nutrition Updates (2006). Probiotics & bowel inflammation. Issue 247, March 2006.
Jamali M, et al. JOP. J Pancreas (Online) 2007; Digestion 2005; (PMID 16172546)
Oku T, et al. JOP. J Pancreas (Online) 2007; Digestion 1972; (PMID 4671520).
Various Wikipedia articles (no references cited)
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