Your digestive system, your gut bacteria, and your immune system all contribute to your fatigue.
You can take care of your digestive system, take control of your health, and learn to love your gut.
Some people have referred to the gut as the “peripheral brain.” This may be true. It is said that the gut contains an equal amount of nerves to the brain and spinal cord. Some neurotransmitters, like Serotonin, are made primarily in the gut.
And gut bacteria? A string of the current papers on the gut microbiome could probably stretch to the moon and back. We are constantly hearing about bacteria in the gut.
Do I have healthy gut bacteria or not? Could my gut health relate to my fatigue, be a factor in my low energy? These are critical questions, and by simply asking the questions, you have made the first steps towards healing.
We talk about gut feelings, gut impressions, and going with your gut. All of these common expressions reflect the merging of the gut and the brain. The science and understanding of the gut-brain relationship is developing daily. This blog will keep you up to date on the current research and thinking.
At the end of this blog, you will have begun to see that it is essential to include your gut into any discussion of health. Especially a discussion on fatigue.
Immunology. Nerves. Neurotransmitters. Bacteria. I almost forget to mention that the gut is really important for doing even more basic things.
Like digesting and absorbing our foods.
To understand your digestive system today, heed the past
As a functional medicine doctor, I try to retain the important teachings of my professors in my head. I figure if I still remember something, it probably has some value.
A professor in my fellowship once said:
“When in doubt, start with the gut.”
Hippocrates beat him to this quote. Four centuries before the birth of Christ, he said that “all disease begins in the gut,” and this truth bears out even more strongly today.
We’ll start our journey with a quick trip back into time. One hundred years, more or less. It was over a century ago that scientists began to really look at the gut bacteria as having a contribution to disease and health.
But first, an aside.
At the start of medical school, I inherited a set of medical books that were written around 1905. I often look up medical conditions to see how things were approached a century ago. The following is an excerpt (with a photo) of what was known about the digestive system circa 1907.
Doctor Sir William Osler wrote, “there is considerable experimental and clinical evidence to prove that normal intestinal flora is useful in protecting the individual against accidental pathogenic invaders.”
Check out the second sentence under “Defensive Role of the Intestinal Bacteria.” Osler correctly observes with “little doubt” that the Bifidobacter organisms ”exercise some inhibitory effect on pathogenic organisms.”
Is it possible that doctors in Osler’s time were recognizing the importance of gut bacteria for health? It appears so. The passage alludes to a type of bacterial already known as bifidobacter. Scientists knew that people who had this bacterial species often had better gut health. For a hundred years it has been known that the type of bacteria in the gut related to better health.
At the end of the paragraph, he states that “lactic acid may exercise a restraining influence on the growth of pathogenic organisms.” An acidified gut was known to have less disease. We now know this lactic-acid secreting bacteria to be of the lactobacillus strain. Look in any probiotic, and this is likely the first bacterial strain that you’ll see.
Cultures around the world have incorporated cultured foods, pickling and yogurts, for millenia. Each of these fermented foods are high in these acid-producing bacterial strains.
As they say, the more things change, the more they remain the same.
True health requires that you know and care for your gut
In the 25 years since I was in medical school, our understanding of the gut health has evolved remarkably. My medical school gut training was pretty simple.
- There are bacteria in the colon
- There aren’t many bacteria in the small intestine, if any at all
- The stomach makes really strong stomach acid
- Somewhere in the gut a bacteria makes Vitamin K. Vitamin B12 is absorbed in the end of the small intestine (terminal ileum)
- Cancers and ulcers are diagnosed with scopes
- Sometimes diseased parts of the gut need to be removed
- Food goes in
- Poop comes out
Congratulations! You just passed first-year Medical School Digestive System training!
I am sure that you recognize my sarcasm. Sadly the truth was not too far off. Our understanding of the dynamics and complexity of the gut has changed immensely. We now recognize the gut to be a dynamic, complex, and individually unique ecosystem.
This uniqueness is a microbial fingerprint.
Each collection of bacteria is uniquely you.
Let’s jump to the gut circa 2018. We will need a different list for our new medical students. (That’s you!).
- The gut contains approximately 100 trillion bacteria. By comparison, the human body is made up of about 10 trillion cells. Cell per cell, we are about 1/10 human cells, and 9/10 bacteria. Wow.
- The intestinal bacteria at the gut barrier were formerly thought of as “us” and “them” relationship. “Us” meaning human cells; “them” meaning everything else.
- The gut “biome” is becoming known as a “we.” We, along with the bacteria within and upon us, have formed a genetic “superorganism.”
- The gut is a dynamic and complex barrier. It is a semi-permeable wall It is like a checkpoint that allows in some things, like our nutrition, and tries to keep others out.
- The gut bacteria control our energy, our nutrition, and our biochemistry. Having the the right kind of bacteria in the gut is the first step to increase your energy and decrease fatigue.
- The gut is essential to detoxify.
And of course,
- Food goes in
- Poop comes out
A good understand of the digestive system begins with anatomy.
Let’s review the gut anatomy in three parts.
Over the course of these lectures, your knowledge and understanding of the gut will grow. This is just the primer course. You will learn how this all fits in the big picture of health.
You will begin to understand how your fatigue could come from your gut.
Let’s simplify things, for starters.
The gut from tip to tail is approximately 30 feet long. Let’s start by breaking this length into three parts.
Part 1: The brain, mouth, stomach, immune (preparation and storage)
Part 2: The liver, pancreas, gallbladder and small intestine (digestion)
Part 3: The large intestine (storage, detox, and evacuation)
Over time, this designation into three parts will help us to direct and interpret testing.
Different parts of the gut may be causing your fatigue for different reasons.
Part 1: The upper gut: brain, mouth, stomach, and immune. Preparation and storage
This initial part of the gut includes the brain, and includes the mouth and teeth, esophagus, and the stomach.
The gut clearly is important for the digestion of food. The digestive process actually begins in your brain before even a small morsel of food passes by your lips. With just the thought of food, the brain begins to prepare our body to receive our nutrients.
It tells the mouth, “start making saliva (salivary amylase), to begin breaking down starches.”
It tells the stomach, “food coming soon, begin making stomach acid.”
Our brain tells our intestines to begin to increase their blood flow. It tells our gallbladder to start concentrating bile, and our pancreas to get ready to deliver digestive enzymes.
Food is chewed (ideally 20+ chews per mouthful), and passed into the stomach. Here churning and turning starts to break our foods into smaller, more easily digestible pieces.
The food is stored in our stomach for 3-4 hours. Gastric cells, found in the antrum at the downstream side of the stomach, make strong stomach acids to begin the process of digestion.
The first part of the gut is also where our immune system has its first crack at microbial invaders. Our sinus cavities in the nose, and tonsils in the throat, help us to identify and repel infections and toxins.
Part 1 gut review:
- Intake of food
- Initial digestive steps
- Storage in the stomach
- Initial immune exposure
Part 2: Liver, pancreas, gallbladder and small intestine (digestion)
The second part of the gut involves the remainder of the small intestine. The small intestine has three parts. The duodenum receives the food from the stomach, and receives the ducts from the liver, gallbladder and pancreas. This all happens in the first 10 inches or so of the small intestine.
The jejunum and ileum, respectively, are farther downstream, and absorb our nutrients and house the immune cells. They make up about the next 19 feet of small intestine in a 50/50 ratio.
In the jejunum and ileum, the gut develops a massive amount of surface area, equal to a doubles tennis court, to digest our food. We need this area to fully absorb our nutrients. The flip side is that this is a greater surface area that our immune cells need to defend.
The partially digested food leaves the stomach through a valve, the pyloric sphincter, into the first part of the small intestine, the duodenum. The pancreas releases pancreatic enzymes, which break down proteins, carbs and fats. The liver makes bile, which is stored in the gallbladder. Bile emulsifies fats, and is crucial for their digestion.
In another post, we will discuss the specifics of the gut anatomy. The structure, blood supply and relation to the immune system all play a role in health and fatigue. In time, it will be important to have a working knowledge of the microscopic anatomy of the gut lining.
With a slightly tighter focus, we can access a window into what drives the immune system, and why it does what it does. And all of this will help us to understand how it is that your gut function, or lack of function, can make you tired, and sap energy.
Carbohydrates are absorbed almost immediately. They are rapidly taken across the lining of the small intestine. The hormones insulin and cortisol direct the cells to burn the sugars, or to store them for a rainy day.
Proteins are broken down into amino acids. Amino acids are the building blocks of life, and allow us to make muscle, tissues and signaling molecules. Thyroid hormone is made from an amino acid. So, too are many of our important neurotransmitters. If you are tired all of the time, it could be due to a deficiency of amino acids.
Remember: There are 20 amino acids. 9 of them are essential, meaning that we can’t get them from our diet. They need to be obtained (and digested, and absorbed) from our food.
Fats are basically strings of carbon atoms. Short-chain fats are, well, short. They are 2-4 carbon atoms in length. More complex fats are longer, typically in the 18-20 carbon range. Medium chain fats, the darlings of Bulletproof Coffee and Coconut-oil diets, are in the 8-12 carbon range.
Our body needs fats. Every cell in the body has a membrane made entirely out of fat. Fats are essential for:
- Storing and making energy
- Immune response, both pro and anti-inflammatory
- Signaling molecules between cells
Our body needs fats. We just don’t need too much of the wrong kind of fat.
Want to feel better? In coming posts we will be spending a bit of time reviewing how essential fats can improve our mind, our bodies, our health, and our sense of fatigue.
Part 3: Large intestine/colon. Storage and removal
A decade ago I would have never considered the colon as one of the causes of fatigue. But times and science change. Our understanding of the complexity of the large intestine is miles from what I learned in Medical School.
Years ago I was taught that the large intestine, AKA the colon:
- Stores digested food and waste
- Controls water balances in the body
- Absorbs vitamins, namely vitamin K and some of the B vitamins
- Contains lots of bacteria
These statements are all true. We now have the following additional insights:
- The colon contains close to 100 trillion bacteria
- Several hundred bacterial species exist in the colon
- These bacteria have active DNA. Humans have about 30,000 genes. The sum total number of genes of the colonic bacteria are estimated at 2,000,000-5,000,000!
- The colon contains bacteria that ferment fiber into short chain fats. These small molecules nourish the gut cells, and direct our immune system
It is possible that we are just beginning to recognize the importance and relationship of the bacteria in our colon? Studies are emerging that associate bacterial strains with anxiety, depression, and fatigue. Cardiovascular disease, autism, and Alzheimer’s disease are all showing to have discrete associations with gut microbes and the health of the colon.
They say that the gut is the second brain. The colon may the genetic control center, driven by the bacteria within.
The gut/immune barrier 2018: The gut as bouncer, general and diplomat
From the earlier paragraphs, you now understand that the gut wears several hats. It serves as a storage area, and promotes digestion and absorption of our food. It welcomes some bacteria and yeast species, and rejects others. It also requires the body’s greatest focus for immune surveillance.
It turns out that some seventy percent of the body’s immune cells rest within one centimeter of the lining of the gut. This should be no surprise. The gut protects us from the environment. The entire environment has access to our inner workings across the lining of the gut. If we can smell, taste or swallow something, it needs to be evaluated by our immune system.
(I recommend that you read Love Your Immune System; Leave Your Fatigue. The five-minute course in how the immune system works. Here we simplify what the immune system is trying to do, and how it does it. Cool stuff.)
Bottom line: The immune system responds to molecular signals with either tolerance, inflammation, or a combination of the two. As our gut immune system is more on the alert, it makes more inflammation.
With more inflammation, the gut lining begins to break down.
With the loss of its lining, the gut loses its ability to act as a barrier. This leaky gut allows more of the environment to come into contact with the immune system.
A vicious cycle follows, with more inflammation, leakiness and ultimately, symptoms.
Anyone who has ever had a case of diarrhea knows the symptoms of a gut immune response. When something concerning to the immune system is detected, signaling molecules are released between the immune cells. Blood flow to the gut changes. The gut muscles spasm and cramp. If the diarrhea is severe, a fever may follow, with aching joints, and a fuzzy head. Generally the infection is transient, and passes.
Over time we heal. Our energy returns.
There’s no question that a diarrheal infection, caused by a virus, parasite or bacteria, makes us feel crappy.
Our immune system, in fighting the “invader,” trades a few days of feeling like you are going to die, for actually not dying. We keep our body alive at the expense of a few lost days, a few lost pounds, and a few extra visits to the toilet.
But that was the infection that we recognized! The current literature is showing us that the same immune processes could be in play in the absence of obvious symptoms.
If you were to have a low-grade process, a low-grade bacterial or yeast imbalance, you could suffer from the same low-grade symptoms. Loose stools, loss of body water, ongoing inflammation, and loss of nutrients takes its toll. A microbial imbalance could be the cause of your fatigue!
“When in doubt, start with the gut”
With these lectures, you will understand how our symptoms, our sense of fatigue, and the entirety of our health is tied to our digestive system. It is essential to consider, evaluate and treat the gut.
This website contains the tools to educate you about your gut. It will teach you the ways that the gut can be measured, what these measurements mean, and how you can fix your digestive system.
It is not normal to be always tired. Do you have brain fog, chronic fatigue, depression, anxiety, low energy? Think gut.
And don’t forget the words of your professors:
When in doubt, start with the gut.