Why You Should Care About Your Digestive System

by Baxter and Nina

Chocolate Kouign Amann by Rosie Gibson

At a very primary level, your digestive system is essential for maintaining your health. After those first gasps of air and the initial cry of a newborn, the first action of a new life is to feed! And a digestive system in decline can be one of the first signs of serious illness or advanced age. The digestive system provides the following four basic functions:

1. Ingestion. Using your mouth to take in foods and fluids, chewing the food, and then swallowing both chewed foods and fluids.
2. Digestion. Breaking down what you eat and drink into smaller and smaller particles, which can then be absorbed into our blood. Anything that can’t be absorbed is passed on for elimination.
3. Absorption. The process of passing the small particles of digested food from the digestive tract into your blood stream, where they can be delivered for fuel to your 70 trillion cells by the circulatory system.
4. Elimination. Removing leftovers of the digestive process that you cannot use from your body. 

These four functions are the how your digestive system provides you with the fuel your body needs to function every day as well as to create the building blocks needed for to growth and repair. And this is also how your digestive system removes waste from your body, a process that is as necessary for your health as ingesting and digesting your food. 

In general, staying physically active, eating a healthy diet and taking in adequate liquids, resting after meals if you can and sleeping well, and good oral care helps you maintain the health of your digestive system. However, one of the most important things you can do to keep your digestive system functioning optimally is to keep your stress levels in check, as stress can have a huge impact on your digestion. (Nina can testify to this, because when she's very stressed out, she literally becomes so nauseated that she can't even eat at all!)

Now let’s take a look at the actual components of your digestive system and the related systems, and the effect that stress can have on them.

Mouth, Tongue, Teeth and Pharynx. Digestion begins as you take food and drink into your mouth and start to break down the food into smaller bits by chewing it and mixing it with your saliva, which contains digestive enzymes. In some people, acute stress can temporarily turn off the production of saliva, negatively affecting your initial breakdown of food.

Esophagus. This tube that runs from the back of your throat to your stomach sack moves your partially mixed food and water to your stomach. In some people, stress can interfere with the smooth muscle rhythm that moves food to the stomach, creating difficulty in swallowing. 

Stomach. Continues digestion by releasing stomach acids and enzymes, and by churning the stomach contents to further break down solids and liquids. In some people, stress can negatively affect digestion by contributing to minor digestive problems, such as heartburn and nausea, as well as more serious problems, such as acid reflux and ulcers. 

Small Intestines. After the stomach finishes its work, the small intestines (a 15-17 feet long tube) use more digestive enzymes to break down the food into even smaller particles of sugars, fats and proteins, which near the end of the tube are then absorbed into your bloodstream. In some people, stress can interfere with smooth movement of food downstream and/or with healthy absorption of food into the circulatory system. 

Large Intestines. After the food particles are absorbed, the large intestines (the final 4-5 feet of tubing that follows after the small intestines), allow most of the remaining water content for our food and fluid intake as well as vitamins and salts to be absorbed into our bloodstream. The waste that remains is collected here and then expelled through your rectum and anus in the form of a bowel movement. Your large intestines are also where much of your gut microbiome lives (see below). In some people, stress can affect the performance of the large intestines, resulting in constipation or diarrhea. 

Liver. Although it has many other functions, the liver aids digestion by producing bile salts, which assist in the breakdown of fatty foods. In some people, stress can produce inflammation in the liver that could contribute to the development of serious liver diseases such as cirrhosis, which will ultimately affect digestion (and cause other serious problems).

Gallbladder. Stores the bile salts made by the liver and releases some into the small intestines when fatty foods are detected. In some people, stress can inhibit the normal release of bile from the gallbladder into the small intestines, which will negatively impact your ability to digest fats appropriately. 

Pancreas. Although it has other functions, the pancreas aids digestion through the production and release of digestive enzymes into the small intestines. In some people, chronic stress makes the pancreas more susceptible to diseases, such as pancreatitis, which will negatively affect its ability to produce digestive enzymes.

Gut Microbiome. The community of microorganisms living in our large intestines and elsewhere in our digestive system make up our gut microbiome. Our gut microbiome has a variety of functions, including the metabolism of certain nutrients in our food, the regulation of our immune system, and modulating various behaviors such as hunger, satiety, and sleep. Maintaining a large variety of the organisms in our gut microbiome is important for the health of our digestive and immune systems as well as for the other systems that interact or communicate with our digestive system, such as the central nervous system. In some people, stress can negatively affect the diversity of the gut microbiome, which has a negative impact on our digestion and overall health.

Enteric Nervous System. A semi-independent web of nerves, the enteric nervous system, sometimes called the gut brain, helps coordinate some of the digestive processes that takes place from the stomach to the beginning of the large intestines, and also signals the brain information that results in feelings of hunger and satiety, whether or not you’re experiencing stress, and if you’ve ingested a disease-causing microbe. 

In some people, stress can interfere with normal signaling of the enteric nervous system contributing to gut symptoms such as cramping and bloating, or causing confused signaling of hunger after stress events that leads to stress eating.

Central Nervous System. To help coordinate your digestive processes your brain is in constant two-way communication with your digestive system though your autonomic nervous system and your hormones. Because of this two-way communication, the health of the central nervous influences the health of the digestive system, and the health of the digestive system influences the central nervous system.

And your state of mind has a profound effect on your digestion. When you are in a state of acute stress, your brain shuts down your digestive system temporarily until the emergency has passed. And when stress is chronic and ongoing, your digestion is compromised because your digestive system isn’t functioning optimally. 

On the other hand, when you’re relaxed and in the Rest and Digest state, your brain turns on the digestive functions that were offline while you were stressed, and is able to work in greater harmony with other systems that support good digestion.

Circulatory System. Delivers absorbed food particles to all the cells, structures and organs of your body, including your digestive system organs themselves by the circulatory system. Water not needed for body functions eventually gets delivered to your kidneys for elimination. In some people, stress can disrupt the normal blood flow to the digestive system, especially to the small intestine, which can compromise the absorption of food into your body. 

Immune System. Along the route of the digestive system are immune functions that are an integral part of the immune system. Examples include:

• salivary enzymes in the mouth, which can kill some organisms that come in with our food
• acidic fluid of the stomach sack, which can kill some invading organisms
• Peyer’s patches, special groups of immune cells that line the inside of small intestines, which can detect and start to fight invaders that make it past the mouth and stomach
• gut microbiome, which may help our immune system adapt more quickly to new infections in the gut

So maintaining the health of your digestive system will aid the functioning of your immune system, just as maintaining the health of your immune system will aid the functioning of your digestive system by keeping your digestive system healthy (see Techniques for Supporting Your Immune System with Yoga).

Because of the importance of your digestive system to the health of your entire body, maintaining healthy digestion is an integral aspect of healthy aging. In general, a well-rounded yoga practice will allow you do this by providing the exercise and stress management—especially stress management!—that you need to keep your digestive system functioning optimally. But if you are experiencing digestive problems, you can target your yoga practice to improve your digestion (see How Yoga Helps Your Digestive System).

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The Digestion System and Yoga

by Baxter 

Over the last 2 years, I have had the good fortune to act as faculty for the Niroga Institute’s Yoga Therapy Program in Berkeley, CA. As part of my teaching duties, I was asked to present and teach the group about yoga and the digestive system. This is a fairly daunting task, as the digestive system is a complex system that interconnects with our conscious mind, the unconscious portions of our nervous system via the autonomic systems sympathetic and parasympathetic systems (which we have discussed here on more than one occasion), and our immune and endocrine systems. Despite the enormity of the task, I came to be reminded of a wonderful fact about the digestive system: it has its own nervous system, called the enteric nervous system (ENS). Upon further investigation, I discovered that this system has a lot to do with helping to move food through the small and large intestines, affecting the fluid absorption from the gut, as well as local blood flow in the gut. The ENS is sometimes referred to as an independent gut brain, which seems quite cool. But this is not quite accurate, for while it does have an independent influence on the many gut activities, it interfaces profoundly with the autonomic nervous system and conscious mind as well.

Human Digestive System

In some ways, this is good news. As we have seen before when discussing yoga and stress, if we can influence the autonomic nervous system and shift the patterns of excess sympathetic stimulation to balanced stimulation, including appropriate amounts of parasympathetic stimulation, we can allow for the body to have adequate amounts of rest and replenishment. In fact one lay term for the parasympathetic system is the “rest and digest response!"

When we engage in a balanced yoga practice that includes active poses, resting poses, breath awareness and relaxation, an interesting thing happens: our digestive system often works more efficiently with less unwelcome symptoms (I’ll leave that to your own experience and imagination to figure out what those are!). So, although the digestive system itself is complex, our yoga practices quite elegantly can interface and support the best possible digestion, via our effect on the conscious mind and the background autonomic nervous system.

More specifically, consider restorative practices and yoga nidra when you know you are under lots of stress that could over-activate your sympathetic nervous system (your fight or flight response). If you’re in the Bay Area and would like to learn more about yoga and the digestive system, consider joining me on June 2nd at 4th Street Yoga in Berkeley, CA. See http://www.4thstreetyoga.com/workshops.html for information. 

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