Category Archives: Digestion

The Large Intestines and the Importance of Probiotics

The last internal stop of our process is the large intestine or colon. The small intestines pass the remaining undigested material to the large intestine. Here it is stored and concentrated by absorbing water. The majority of our micro flora are also here – both beneficial and detrimental. Micro flora is also found in the small intestines and stomach.

Once again the internal environment changes as the colon is slightly acidic at 6.8. The large intestine is where sodium, potassium, other vitamins and minerals, and water are absorbed. Of that original seven liters of enzymes the remaining 1.5 liters is absorbed in the colon. Feces made here which are one third matter and two thirds water. A major part of the feces is dead bacteria. There are several pounds of flora in the bowel. The beneficial flora produce B Vitamins, Vitamin K, and will digest proteins.

We have 400 to 500 types of bacteria in our digestive system. This is often simplified as the “good” and the “bad” bacteria. To keep it simple the “good” bacteria are those that live on some of the undigested material and their waste products are vitamins that we can use. The “good” bacteria are called probiotics. The most prominent are: Lactobacilli (Lactobacillus acidophilus, Lactobacillus bulgaricus), Bifidobacterium, and Saccharomyces boulardi.

On the other hand the “bad” bacteria are those who live on other undigested material, mostly the sugar and other carbohydrates, and produce waste that is toxic to our system causing bloating, gas, and many of the other digestive disorders that we previously spoke of.

When we discuss our micro flora or bacteria think of it as continuous war with many battles. All the varieties are battling to survive. When you take an antibiotic (anti-life) it kills all the bacteria – both the good and the bad, but not yeast such as candida which takes over. This is why often have yeast infection after round of antibiotics.

There are a variety of food sources for the good bacteria. These include the cultured or fermented foods such as: yogurt, kefir, raw sauerkraut, kimchi, miso, tamari, and tempeh. Another source is probiotic supplements.

Bernard Rosen, PhD is a Nutrition Consultant and Educator. He works with individuals, groups, and at corporations to create individualized nutrition and wellness programs. He has offices in Thiensville and Glendale, WI. To learn more or to schedule an appointment, e-mail at, call (262) 389-9907 or go to

The Liver, Gall Bladder, and Pancreas – Behind the Scenes Helpers of Digestion

When we think of digestion we usually think of the stomach, small intestines, and large intestines – often collectively referred to as “the gut.” Playing a key role behind the scenes are the liver, gall bladder, and pancreas.

The liver is one of the most critical organs in the body. Once the liver shuts down the body is pretty much finished. Among its hundreds or perhaps thousands of jobs are: cleaning/purifying the blood and removing toxins, fat metabolism, building proteins/amino acid synthesis, and for purposes of digestion – manufacturing bile. After being made in the liver bile is stored and concentrated in the gall bladder.

The acidic food passing from the stomach to the small intestine stimulates the pancreas and gall bladder. Foods high in fat have to be emulsified. This is what bile does. It is a “degreaser”. If the oil is not degreased, the enzymes cannot get to the food.

The body makes 1-6 cups of bile per day. Bile has pH of 7.8 which is slightly alkaline. Gall bladder contractions send bile into the small intestines. Bile that stays in the gall bladder gets reconstituted and thickens and can eventually form stones. This thickening is referred to as biliary stasis which prevents the bile from flowing to the small intestines. One of the problems in eating a low fat diet is by consuming less fat there is less need for bile. This increases the likelihood of biliary stasis.

Bile influences the color of stools. Light colored stools indicate liver and gall bladder need help. Stools should be brown. Any other color is suspect.

The pancreas secretes hormones (insulin and glucagon) and enzymes thus it is often overworked. We have previously discussed the key role that pancreatic enzymes play in the small intestines. We will later discuss the importance of insulin and glucagon.

Bernard Rosen, PhD is a Nutrition Consultant and Educator. He works with individuals, groups, and at corporations to create individualized nutrition and wellness programs. He has offices in Thiensville and Glendale, WI. To learn more or to schedule an appointment, e-mail at, call (262) 389-9907 or go to

The Small Intestines

Our tour of the digestive system continues:

The action now moves into the small intestines. Since digestion is a north to south process whatever happened in the stomach will impact the small intestines. Did we digest our food or did it ferment? Are we taking antacids for acid reflux?

As the food or “chyme” as it is now technically called moves into the small intestines the stomach sends a signal to the pancreas informing it of the amount of carbohydrate, fat, and protein coming its way. The pancreas then prepares the required enzymes. Not to overstate the obvious, but the more work the stomach has done, the less the pancreas and the small intestines will have to do.

As you remember, the pH environment of the stomach is supposed to be acidic. However, the pancreatic enzymes only work in an alkaline environment. Secretions from the pancreas and bile from the gall bladder alkalinize the small intestine. The pH of small intestine should be 8.3. Without sufficient bile, the small intestines do not reach this pH.

Normally, food stays in the small intestine for 3-10 hours. During that time approximately seven liters of enzymes are produced – amylase, protease, and lipase. Ninety five percent of all digestion and absorption occurs in the small intestines. If the pH is not correct this will be compromised and transit time may be shorter (diarrhea) or longer (constipation). During this process 5.5 liters of the fluid is reabsorbed.

When working properly the digested molecules from the food we ate will be absorbed into the blood stream in the small intestines. Once in the blood it will fuel the body. The undigested material is passed on to the large intestine – our next stop.

What happens when food is not adequately digested and absorbed in the small intestines? There are two scenarios. First, food particles not digested well enough to pass across the gut wall pass down the alimentary canal, where they putrefy and form toxins that will be absorbed into the blood. Undigested carbohydrates feed the “bad” bacteria that we will meet later in the large intestines.

Or, the food particles are digested well enough to pass through the gut wall and into the blood, but are not reduced to particles small enough to be utilized by the body. This causes the intestinal mucosa to become inflamed which makes it more permeable. These are typically proteins. If you look at the major food sensitivities, intolerances, allergies, or whatever you want to call them, they are generally related to proteins: gluten from grains; casein from dairy, soy, and eggs.

What else contributes to an inflamed mucosal barrier? Studies show three major factors: therapy with prostaglandin inhibitors (NSAIDs, steroids, prednisone, and cortisone); antacids that decrease the acidity of the stomach, limiting the ability to digest proteins which leads to particles that get into blood leading to immune system reaction; and antibiotics that disrupt the normal balance of bacterial micro flora in the gut as well as the mouth, skin, and vagina leading to an overgrowth of bad bacteria and yeasts. NSAIDs are non steroidal anti-inflammatory drugs including ibuprofen, aspirin, and naproxen.

As poor digestion (dysbiosis) becomes your “normal” your intestinal permeability continues to increase and is then referred to as “leaky gut syndrome.” Healthy intestinal lining only allows properly digested foods to pass through into the bloodstream and be assimilated. It also keeps out bacteria and other foreign substances.

If the gut leaks these “things” get into the body a wide variety of symptoms and health problems are associated, including: abdominal pain, gas, indigestion, bloating, constipation, diarrhea, asthma, chronic joint pain, chronic muscle pain, confusion, fuzzy thinking, poor memory, mood swings, nervousness, aggressive behavior, anxiety, poor exercise tolerance, poor immunity, recurrent vaginal infections, skin rashes, bed wetting, recurrent bladder infections, fevers of unknown origin, shortness of breath, primary biliary cirrhosis, and general fatigue and malaise.

Bernard Rosen, PhD is a Nutrition Consultant and Educator. He works with individuals, groups, and at corporations to create individualized nutrition and wellness programs. He has offices in Thiensville and Glendale, WI. To learn more or to schedule an appointment, e-mail at, call (262) 389-9907 or go to

The Importance of Hydrochloric Acid

Here’s a quick three question true or false quiz for you:

1. The cause of gastric/acid reflux is too much stomach acid.

2. When we are stressed, we produce extra stomach acid.

3. Antacids stop acid reflux.

What are your answers? If you are like most Americans you probably answered true to all three. Over the course of our lifetime you have most likely heard endless advertisements telling you so. Well, sorry. These are all false! They are common misconceptions.

Acid indigestion is a misdiagnosed and misunderstood condition. Here’s two important points you need to understand. First, acid reflux or GERD does not necessarily mean that there is too much stomach acid or HCl, which is a common belief. The actual truth is that many people diagnosed with acid reflux (too much stomach acid) actually produce too little.

Second, there are other acids in the stomach besides HCl. These are the true acids of acid reflux. So where do they come from? Food enters the upper part of stomach where it can sit for up to an hour waiting for the body to produce enough acidity to activate its enzymes for protein digestion.

In a young, healthy person it takes approximately 45 minutes for the stomach to reach the pH that releases pepsin. During this time the salivary enzymes continue to work. If we ate some raw foods we would also have those enzymes assisting in digestion. However, if we eat mostly cooked food and overeat it, something else is happening – it is decaying rather than being digested. Decaying food produces organic acids of putrefaction and fermentation – these are the acids of indigestion.

In addition, people who suffer from indigestion are often stressed, and eat in a rush, on the run, or while upset. We have been told stress makes our stomach pump out too much acid, causing heartburn and ulcers. But here’s the truth about stress and digestion.

The actual fact is that stress engages the sympathetic nervous system. This suppresses digestion, and thus HCl production. Think about it. Our sympathetic response is also called “fight or flight.” Back in the good old days if you saw a tiger (that would be a stress) you would want to run as fast as possible to get away. The alternative of fighting it would be a losing proposition. If you are running from a tiger your body is not worried about digestion. The same thing occurs when we eat while stressed. The body does not worry about making enzymes so the food sits longer in the stomach.

Producing insufficient HCl is called hypochloridria. A sympathetic nervous system response is one factor. There are others. As we age we make less HCl. In fact, by age 65 we make about 15% of the HCl we produced at age 25. Ever notice how more of the elderly seem to have acid reflux and other digestive issues?

Other causes include excessive use of antacids, a salt-free diet, chronic illness, and an increased metabolic demand (such as sports). Hydrochloric acid is made from hydrogen and chloride. Salt, better known as sodium chloride, is a source of chloride. Zinc is a key mineral required in the body’s process of making HCl. Chronic illness can deplete zinc. It is also rather ironic that zinc requires an acidic environment in the stomach to be absorbed. This requires HCl. So, HCl requires zinc and zinc requires HCl. An increased metabolic demand also burns up the minerals needed to make HCl.

How do you know if you are hypochloridric? Symptoms include: burping, bloating, bad breath, indigestion. Gas is the first sign that food is not digesting – it is rotting. As I said before fats go rancid, proteins putrefy, and carbohydrates ferment producing the “organic acids” of acid reflux.

At the root of acid reflux is poor diet – The Standard American Diet (or appropriately abbreviated as SAD). This is a diet high in processed foods, carbohydrates, starches and sugars, heavy in meat and particularly processed meat, and low in fiber. Don’t get me wrong, there is nothing wrong with meat, it is just the quantity with respect to other foods and the overall quality that most Americans eat that is problematic. At the same time the diet is low in nutritious foods such as vegetables and healthy meats. Poor digestion occurs from the combination of poor food quality and lack of good bacteria and sufficient enzymes.

Other triggers for acid reflux include: tight fitting clothes, lying down too soon after eating, eating large meals, and specific foods that irritate (such as tomatoes, citrus fruit, dairy, meat, alcohol, coffee, high-fat foods, fried foods, spicy foods, onions, and chocolate).

While acid stopping medications and antacids can make the resulting symptoms better in the short term, but make the original problem worse! Here’s why. We are essentially turning off digestion at the stomach and attempting to resume it in the small intestines.

We know this is not a good idea! As we learned we need an acidic stomach to digest proteins and specific key nutrients (calcium, iron, zinc, and Vitamin B12). Without these we can become malnourished and lacking key nutrients. This can lead to protein deficiency problems, B12 deficiencies, nail problems, iron anemia, allergies, and osteoporosis.

As mentioned earlier HCl kills bacteria and parasites. Without it, we are more susceptible to them. They too are linked to a wide variety of illnesses. Rotting food also contributes to degeneration of the gastric mucosa, increasing the likelihood of a gastric ulcer.

And perhaps most important – digestion is a north to south process. If we get behind in the stomach this places extra burden on the downstream organs.

Bernard Rosen, PhD is a Nutrition Consultant and Educator. He works with individuals, groups, and at corporations to create individualized nutrition and wellness programs. He has offices in Thiensville and Glendale, WI. To learn more or to schedule an appointment, e-mail at, call (262) 389-9907 or go to

The Stomach

The Stomach

Now that we’ve made it through the esophagus and into the stomach, the next two blogs will focus on it. This first article talks about what is supposed to happen in the stomach and the second article discusses the importance of hydrochloric acid and much of the misinformation on that subject.

The stomach is where some serious digestion is supposed to start. As mentioned it can hold one liter (four cups) comfortably. It will stretch to hold more, but may struggle to process all of it properly. The stomach makes hydrochloric acid (HCl) to facilitate the digestion process. As the stomach stretches to accommodate food, this signals the body to make HCl. The stomach concentrates the acid to lower its pH below 3.0, ideally getting down to 1.0 to 2.0.

To protect itself from HCl the stomach makes mucus for its lining. And here’s a critical point. HCl does not digest food; it only serves to get the stomach acidic. Once the stomach is acidic pepsinogen is released. This makes pepsin which begins protein digestion.

The stomach also makes what is called intrinsic factor to digest Vitamin B12 and lipase to digest fats. Also note there is no carbohydrate digestion in the stomach. If the stomach is not acidic enough pepsinogen will not make pepsin and lipase will not be released. This means digestion is not occurring!

The acidic nature (and thus HCl production) of the stomach is critical for several other reasons. Of prime importance is to purify our foods. HCl will de-activate plant, animal and synthetic hormones and antibiotics from animals.

Stomach acid kills bacteria and viruses so they cannot get to other parts of our body. The bacteria H. Pylori turns off the stomach’s ability to make HCl. It has been recognized as the root cause of stomach ulcers. This bacteria eats away the stomach’s lining. Without HCl the body cannot kill the bacteria without additional support.

HCl is necessary for protein, B12, iron, and calcium absorption. Protein is the structural basis for our body – our muscles, ligaments, tendons, organs, glands, nails, hair, vital fluids (blood, hormones, neurotransmitters), and enzymes are all protein based. It builds and repairs all these tissues and cells.

Vitamin B12 is important for many functions. It is a cofactor for two important enzymes. One used for the metabolism of methionine, an essential amino acid. The other aids the production of energy from proteins and fats. Overall Vitamin B12 supports the nervous system, promotes the maturation of red blood cells (hence the tie to anemia when deficient in B12), and supports bone and joint health.

Iron is critical for the health of our blood. One-third of our 100 trillion cells are red blood cells! Iron aids in hemoglobin production, which is critical in the transportation of oxygen around the body. Oxygen fuels the body and hemoglobin helps get it around! Iron also supports enzyme formation and function and is part of the enzyme system that produces DNA – the blueprint of the body – so it is critical in growth, reproduction, healing, and immune function.

Iron is tricky as too little can cause anemia—but too much can lead to atherosclerosis and other cardiovascular problems. Unlike other minerals, excess iron is not excreted from the body. Instead, it’s stored in the tissues, accelerating iron overload indefinitely.

Calcium is one of the most talked about minerals and for good reason. It supports strong bone structure, teeth, and muscle tissue, aids in blood clotting function, supports cardiovascular and nerve functions, and helps in normal functioning of many enzymes. I repeat, without HCl we cannot effectively absorb calcium. So, if you are taking both antacids and calcium supplements what do you think is happening (or not happening)?

If all is going well, the stomach has begun the process of breaking down the proteins and fats and some key vitamins and minerals are being absorbed. Next stop is the small intestines. But before we get there, we’ll explore how digestion can be compromised in the stomach, which of course has significant impact as we continue down the north to south path.

The Esophagus

The Esophagus

We return to our north to south tour of the digestive system. Next stop after the mouth is the esophagus. Actually the esophagus is more like a transit point. We do not want anything to stop there! The esophagus is the passageway from the mouth to the stomach.

It has upper and lower valves. The upper valve insures that food goes into the esophagus and not the trachea (which is used for moving the air we breathe into our lungs). The lower esophageal valve prevents food from coming back up. This valve can become incompetent and not stay completely shut. When this occurs you may experience “acid reflux” – the “back up” of “stomach acid.”

Several factors contribute to the lower esophageal valve becoming incompetent including a nervous system reaction, hormonal control, and pressure from the stomach. Eating too much food (filling the stomach beyond a reasonable capacity) can press the valve back up. The capacity of the average stomach is just one liter (approximately four cups).

Nicotine, caffeine, sugar, and alcohol have also been shown to make the lower valve incompetent. Once the valve has become incompetent you become more susceptible to experiencing acid reflux on a regular basis. We will discuss acid reflux in much more detail later.

The Importance of Enzymes

I cannot overstate the importance of enzymes to the digestion process. Simply put, enzymes make stuff happen in the body- basically they keep you alive! They are proteins that enhance and accelerate chemical reactions in the body. Since there are many different reactions there are many different enzymes. The human body has more than 55,000 different enzymes! With respect to digestion there are two types that are significant. There are enzymes that are found naturally in real food (food enzymes) and there are enzymes that our body makes to help break down the food we eat (digestive enzymes).

All real food of plant and animal origin contains enzymes. Each raw, uncooked fruit, vegetable, or meat contains enzymes that will digest the food in which they are contained. For example, what we commonly consider as “bruising” on fruits is actually enzymes in action eating up the fruit. There is one small problem with food enzymes. They are easily destroyed by cooking and processing – generally at temperatures above 115°. Since most of the food we eat is cooked or processed that means we have become dependent upon our body to produce sufficient enzymes to digest our food.

While in general we should have sufficient enzymes, there are times we may not. For example, lactose (milk sugar) intolerance is widespread throughout the population. This is because not all humans make or have sufficient amounts of the enzyme lactase required for digesting lactose. Or sometimes we just plain over-eat and our body is not able to produce all the enzymes required within the time allotted.

The main enzymes made by the body are proteases, amylases, disaccharidases, and lipases. Another important enzyme is cellulase which the human body does not manufacture. As you’ll notice, all enzymes end with “ase.”

Proteases digest proteins. They begin their work in the stomach. A protease deficiency can lead to a compromised immune system, fluid retention, constipation, excessive alkaline reserves, and calcium metabolism problems. As I have written previously, one of the dangers of soy protein is that it actually contains protease inhibitors. So, while it is sold and marketed as a protein, which it technically is, the body struggles to digest and utilize it due to the fact it cannot be digested. (Note that fermented soy products such as tempeh and miso are digestible because the protease inhibitor has been broken down by the fermentation process.) Soy mixed with other proteins will also inhibit their digestion. When we discuss the stomach there will be additional information relating to the consequences of insufficient protein digestion.

Amylases digest carbohydrates (starches and sugars) and break them down into disaccharides (sucrose, lactose, and maltose). The disaccharidases further digest these sugars into their simple components called monosaccharides (glucose and fructose). Carbohydrate digestion begins in the mouth and then resumes in the small intestines. Excessive consumption of carbohydrates (sugars) can produce a deficiency of disaccharidases. Some examples of amylase and disaccharidases deficiency include: lactose intolerance causing diarrhea; maltose and sucrose intolerance causing diarrhea and/or constipation; general sugar intolerance leading to asthma and sleep issues. In addition a variety of mental and emotional imbalances such as depression, mood swings, aggressive behavior, panic attacks, and hyperactivity have been linked with deficiencies of these enzymes. Of course in reviewing this list one must discern whether it is the actual lack of the enzyme (such as with lactose intolerance) or the overconsumption of carbohydrates/sugars with a resulting supply shortage of enzymes. Sugar and fructose block Vitamin B metabolism and lack of Vitamin B is also related to the above described mental and emotional issues.

Lipases break down fats. Fat digestion occurs in the small intestine after the gall bladder secretes bile into the small intestines. High cholesterol, high triglycerides, high blood pressure, difficulty losing weight, varicose veins, and diabetes may be signs of lipase deficiency.

Cellulase digests soluble fiber such as cellulose found in vegetables. Ever notice how some raw vegetables may give you gas? While the raw vegetables do contain some cellulase, it may not be sufficient for your body to digest them.

Digestive enzymes are available as supplements and I encourage my clients to utilize them for three reasons: 1. Since enzymes are so critical to digestion; 2. Most of the food we eat is cooked and processed; and 3. Most people eat too much and out of balance. I like to call them “life savers” or insurance for your digestive system.

Bernard Rosen, PhD is a Nutrition Consultant and Educator. He works with individuals, groups, and at corporations to create individualized nutrition and wellness programs. He has offices in Thiensville and Glendale, WI. To learn more or to schedule an appointment, e-mail at, call (262) 389-9907 or go to

The Mouth – Why Chewing is Important

The “physical” aspects of digestion begin in the mouth. Please consider what goes in our mouth is generally a volunteer action! For the most part we choose what we eat, how many times we chew our food, and the pace (fast/slow) of the eating experience. Some may argue that digestion begins before we eat as the smells, sounds, and overall environment affect us. To some extent I’d agree with this. It is a biological fact that if we are stressed our digestion is adversely impacted. No reason to digest if you’re running away from a lion or tiger, right? And, if we are in a pleasant environment, calm and relaxed, this will aid our digestion. Nothing like the smell of grandma’s cooking to get the digestive juices flowing. But, at the end of the day if we gulp down crappy food we’re going to have digestive issues.

In our mouth we have our teeth and the salivary glands (of which the parotid is the largest). Our teeth are very important as they are the first stage in breaking up our food so we can process it. The more we chew and break up the food, the more surface area there is to be acted upon. Saliva contains mucus, lysozymes, and amylase. Believe it or not, we make 1-2 quarts of saliva per day! Saliva should be alkaline with a pH of 7.4, although it can vary throughout the day. If you would like to test your saliva you can purchase pH paper. The most accurate reading is in the morning after waking up. If saliva is acidic (pH < 7) it will interrupt digestion of carbohydrates in mouth. The saliva pH is indicative of general health of the liver. Mucus is important because it lubricates the food to help it pass through the esophagus. Lysozymes poke holes in the walls of bacteria which weaken them so they can be taken care of (eliminated) by the stomach. Amylase is an enzyme and it begins the digestion of carbohydrates. Ever notice how if you have a piece of bread in your mouth for awhile it starts to taste sweet? This is the carbohydrate breaking down into sugars. It appears the body was designed to handle carbohydrates first. So what we do in the mouth is very important. If we do not chew our food sufficiently more work has to be done in the stomach to break the food down. Remember – this is a “north to south” process. How many times to chew? I’ve heard anywhere from 20-40 chews per mouthful. The 40 seems a bit stretching it, but 20 seem reasonable. And, the more we chew the more saliva is produced and mixed with the food providing the mucus, lysozymes, and amylase required. Not enough mucus and the food has a harder time getting to the stomach. Too few lysozymes and it is more likely for harmful bacteria to survive. Short on amylase and carbohydrates do not get broken down and begin to ferment in the stomach since their next chance for activity is in the small intestine (but I’m getting ahead of myself). I’m sure you can see how each step has an impact on what takes place next. If the initial job is not done correctly the next step needs to catch up or make an adjustment. Bernard Rosen, PhD is a Nutrition Consultant and Educator. He works with individuals, groups, and at corporations to create individualized nutrition and wellness programs. He has offices in Glendale and Thiensville, WI. To learn more or to schedule an appointment, e-mail at, call (262) 389-9907 or go to

Digestion – Introduction – The Body Positive

Digestion – Introduction

Our tour of the body begins with the digestive system. After all, we are what we eat! What we put into our body provides the fuel our body has to work with in performing all the functions that give us life. Without food there is no life. Without strong digestion there is no useable fuel. What we eat and drink needs to be processed and utilized by the body. Therefore, when I speak of “digestion” remember it is inclusive of breaking down our food, absorbing our food, utilizing our food, and removing the waste products of the food from the body. All of these are critical steps in what we term “digestion.”

Many people suffer from poor digestion (dysbiosis). Do you? How would you know? Well, common signs of poor or compromised digestion include heartburn, belching, burping, gas, bloating, cramping, constipation, diarrhea, nausea, and vomiting. But did you know bad breath, rashes, skin eruptions, acne, allergies, and autoimmune diseases stem from poor digestion as well? When your digestive issues get serious enough for you to see your doctor you may receive an official medical diagnoses such as: Acid reflux, GERD, Crohn’s, irritable bowel syndrome, colitis, diverticulitis, inflammatory bowel, Celiac, and others.

When we have “symptoms” this is our body sending us a message. Something is wrong. Something is not working as designed. Our body has over 120 trillion cells, all of which need to be nourished. Everything we put into our mouth will ultimately have a consequence – either it is nourishing or it is stressful. One definition of nutrition is an act or process of being nourished. It is through digestion that we receive our nourishment.

The next big question is: What creates symptoms? Obviously it is not how our body was originally designed! As my friends at the IFNH (International Foundation for Nutrition and Health) like to say, “Digestion is a north to south process.” It has several stages and what happens at each phase is greatly influenced by the preceding phase. The digestive system includes: mouth, pharynx (throat), esophagus, stomach, small intestine, liver, gall bladder, pancreas, large intestine, rectum, and anal canal. Now we’ll learn what each part does.