Understanding the Complex Digestive Process
The digestive system is a true natural wonder that is greatly underappreciated by most of us. Gaining a better appreciation for this important part of your body will help you to take better care of it and help you understand what causes digestive problems such as diarrhea, constipation, chronic abdominal pain, gas, and bloating.
The Organs of the Digestive Tract
Your gastrointestinal tract is a long tube. This tube starts at your mouth and ends at your anus. If you were to stretch it out to its full length, would be about thirty feet long, about twice the length of your car, with a surface area approximately the size of a tennis court.
This tube is a highly specialized organ that is designed to do three very important things:
- Convert food into something your body can use for nourishment
- Protect you from invading bacteria, viruses, and toxins
- Dispose of a variety of waste products
The digestive system is so highly specialized that it is the only organ in the body that has its own special nervous system, often called a second brain. It also comes with a huge defense system to protect it from outside threats. In fact, the majority of our immune system resides in the lining of the digestive tract.
But that’s not all. This tube contains a highly evolved ecosystem of organisms which are not only critical to proper digestive function, but are also a vital part of the defense system. All of these components of the digestive tract communicate and work together to keep you healthy. But if something goes wrong, you can already start to imagine a problem in the digestive tract has the potential to have a big impact not only on your digestion, but on your overall health.
The “Normal” Digestive Process
A lot happens between the time you eat a piece of food and the time you go to the bathroom. Most people are concerned only with the two parts of the digestive system that require some active participation on their part, the food going in and the waste coming out. The multitude of other steps between these two poles are involuntary, and you probably don’t pay a lot of attention to them.
When it’s all working well, normal digestion is an unremarkable experience. You typically have one to two bowel movements per day. They aren’t urgent, they don’t cause any discomfort, there is very little noticeable gas production, and they only take about five minutes.
Stools should be well-formed and not watery, generally dark brown in color, and passed easily without straining, cramping, or pain. And a healthy stool does not float in the water.
Ideally, at the end of the bowel movement, you should feel like you are fully through, and you shouldn’t need to wipe much. Pooping is a natural experience and should be comfortable and can even bring an enjoyable feeling of release.
As food travels through your digestive tract, it moves down the tube by an involuntary process called peristalsis, a wavelike muscular contraction that carries the nutrients and subsequent waste products from top to bottom. This movement is controlled by the digestive tract’s private nervous system. Eating triggers peristalsis. Therefore, about 30 to 60 minutes after eating, depending on various factors including how much was in the intestinal tract to begin with, a person may feel the urge to have a bowel movement. This bowel movement is not the same food you just ate.
Technically speaking, anything inside this tube is not really inside your body. It is still part of the exterior world. Only once it has been processed and broken down does it pass through the intestinal wall at a cellular level and actually move to the inside your body. This tissue wall is a permeable “skin,” similar in many respects to the skin that protects you on your other exterior surfaces like your arms, legs, torso, and face. Like your outer skin, this layer of tissue is protective, but unlike the skin that you see, it is highly specialized for digestion and absorption.
The food breaks down into smaller and smaller substances as it moves down the tube in stages. Chemicals necessary for digestion and absorption, including acid and enzymes, are secreted into different sections of the tube. Muscular valves close off portions of the tube while chemical processes are carried out at each stage.
Different areas of the digestive tract absorb different materials needed for life: vitamins, minerals, fats, amino acids (proteins), sugars (carbohydrates,) and even water. Waste is also created at each step and moves down the tube toward the exit. All of these functions are highly coordinated, working together to provide you with proper nutrition.
About 60 percent of the fecal mass is made up of water, although this figure can vary widely. When you have diarrhea, for example, the percentage of water is much higher.
Another 30 percent of a normal stool consists of dead bacteria, which gives feces its characteristic odor. These bacteria are from the vast ecosystem of bacteria that lives in the digestive tract. The rest of the stool is made up of indigestible fiber, fats (such as cholesterol), inorganic salts, live bacteria, dead cells and mucus from your intestinal lining, and protein.
A Majority of Our Immune System is in Our Digestive Tract
Inside of your digestive tube is a vast ecosystem where some 100 trillion bacteria live, and this should not alarm you. We have been conditioned to think of bacteria as something bad, and the thought that we have 100 trillion “bugs” inhabiting our body can make us feel slightly queasy. But we now are beginning to appreciate the importance of these bacteria, and they have become known as the microbiome.
Although some bacteria are bad, others are very good. In fact, if you don’t have them, you feel very bad, because they are critical for proper digestion.
These bacteria have several important jobs:
- They help to break down food
- They create some vitamins
- They work directly with the immune system surrounding the digestive tract to protect us from bad guys
- They also independently protect us against invading organisms
Our relationship with the 100 trillion bacteria in our digestive tract is not new. It has developed over hundreds of thousands of years. There should be no doubt about the importance of this ecosystem to good health.
The digestive system also contains 80 percent of your immune system, which defends you from invaders coming down the pipe. The immune system is critically important in helping the digestive system react to bad bacteria and viruses that may be found in our food or accidentally ingested. Possibly the greatest challenge to the digestive tract’s immune system is to correctly tell the difference between what is bad, such as viruses and bad bacteria, and what is good, such as nutrients and good bacteria.
Recent advances in DNA analysis have enabled us to determine the different kinds of organisms living in the digestive tract. In just the last few years, researchers have created tests that analyze the DNA of these organisms and can determine which are healthy microbes and which are pathogenic microbes. This dramatic advance is available to physicians, though they are mostly used only in research facilities.
Your immune system must also determine whether or not to develop a reaction to everything that you put into your mouth. Whenever you try a new food, it must decide, “do I like this and let it go, or do I attack and kill it?”
You are always ingesting bacteria and other substances with your food, no matter how fresh and clean it is, so these must be screened out. While your immune system will say okay to most foods, genetic and other issues may affect its decision.
Recent studies also suggest your immune system’s ability to develop correct tolerances depends a great deal on the balance of good bacteria inside your intestinal tract. When you put something into your mouth that the immune system doesn’t like, it attacks with inflammation and excess mucus production. If your immune system is continually bombarded with messages to attack, its reactions can lead to long term inflammatory consequences.
Inflammation of the digestive tube can, in turn, lead to damage of the lining of this tube, often resulting in something called leaky gut or gut hyperpermeability. These two terms are simply descriptions of the damage to the digestive tract that is a result of something triggering an immune response.
Stomach Acid is Important for Digestion
The myth is that you are what you eat, but in fact, you are what you absorb. Stomach acid is vital to good health. It is the first major step, after chewing and saliva, in breaking down your food.
Acid is especially important for breaking down proteins into amino acids and is required for the optimal release, preparation, and absorption of minerals, such as calcium, magnesium, and iron.
Decreased acid levels can also cause digestive problems further down the line. Pancreatic enzymes, bicarbonate, and bile are all released in the small intestine in response to the acidity (pH) of the food that normally leaves the stomach.
Without these, digestion continues to degenerate, resulting in a far less than optimal nutritional gain from your food and potentially damaging byproducts. The pH, now improperly balanced further down the digestive tract, damages the environment for billions of normal/good bacteria, which are critical to proper digestion and good health.
Vitamin B12 also isn’t absorbed without stomach acid. The same cells that produce acid produce intrinsic factor, which is required for vitamin B12 absorption. Without B12, you become B12 deficient, which can lead to fatigue and neurological problems.
Stomach acid is also your primary defense against food-borne infections. Bacteria don’t usually survive the stomach, so decreased acid increases your risk of food poisoning. Another risk of low stomach acid is poor calcium absorption and therefore low bone density.
Nutrients provide the building blocks for our entire biochemistry. Optimal health requires optimal nutrition which is why you need stomach acid.
Good Digestion Is Critical to Good Health
Understanding the qualities of normal good digestion is vitally important to maintaining optimal health. If your digestion is anything less than perfect, your health is going to suffer. The entire digestive process should be unremarkable, meaning there is nothing to remark about it, because it’s functioning in the background and there is no reason for you to notice it.
If you are noticing your digestion, then it isn’t working properly. Likely you are suffering from some kind of digestive upset, such as abdominal pain, gas, urgent diarrhea, uncomfortable or incomplete bowel movements, or bloating. If anything like this is happening, then your digestive system is sending you a message. It’s saying, “Help me!”
If all you do is take something for the gas, or something to create a solid bowel movement, or something to make you have a bowel movement, then you’ve only treated the symptom. Your digestion still isn’t working properly, and your health is still going to suffer.
The entire digestive function is based on relaxation and this is why stress is often blamed for bad digestion. When you are relaxed, the parasympathetic part of your nervous system is dominant. This same part allows your digestive system to do its thing and operate normally.
Recognize when you are having digestive problems and seek answers. Your primary doctor may not have them, but don’t give up. You may have to keep searching until you can find someone who can help you optimize your digestion. You will be rewarded with better health over your lifetime.