It makes sense that so much of pre-modern medicine was centered on intestinal health and digestion. During Hildegard of Bingen’s time, the notion of humoral medicine prevailed. Hildegard believed imbalance among the four bodily fluids caused illness and disease. Conversely, she thought when the four humors are in balance, health is maintained. Intestinal health was Hildegard’s priority, and a diet rich in fiber was her way to achieve balance.
“All disease begins in the gut” – Hippocrates
The Basics of Intestinal Health
After all, our digestion is the most readily observable bodily processes, and it is where the four humors begin and end.
While the ancients may have been mistaken in their literal view of bodily fluid balance, they were right about how the balance (or imbalance) of our intestinal health impacts our overall health and sense of well-being.
No, we’re not talking about the outstanding 1987 film with Dennis Quaid and Martin Short about a miniature submarine cruising through the guts of a hypochondriac. We’re talking about your gut. Not quite as funny, but even more amazing.
We tend to view digestion as a process that is entirely internal, where deep within our bodies the food we ingest is converted into nutrients, energy, and waste. Makes sense, from our perspective it all happens within our grumbling bellies. In reality, however, the contents of our digestive tract are actually considered to be external to the body, in our own kind of innerspace.
The alimentary canal, or the gastrointestinal (“GI”) tract, is a continuous muscular digestive tube consisting of the mouth, pharynx, esophagus, stomach, small intestine, and large intestine. This long tube acts as an intricate boundary between the external environment and our internal bodies, extracting what is needed and eliminating what is not.
The notion of the contents of our GI being external to our body is admittedly semantic, but it is instructive when considering just how much of health or illness is about the various frontiers between the external environment and our more delicate insides.
And, given that our digestive tract is a 30-foot long frontier in which we introduce external stimuli, including dangerous pathogens like bacteria, protozoa, fungi, viruses, and even toxic substances on a daily basis, it makes sense that our GI is central to our well-being.
Immune System and Intestinal Health
In fact, the GI is where the majority of our immune system operates, accounting for around 70% of total immune function. This space inside of us is where our body not only extracts the resources we need to survive, but also acts as the front-line in defending against illness.
Like our skin, our digestive tract is as an active immune organ as well as a reflection of our overall health. When our digestion is healthy, we are healthy – and vice versa.So how do we maintain healthy digestion?
Hildegard recommended some ways to improve digestion that are true to this day. But before we get there, we have to understand that our GI is indeed a frontier – and like most frontiers, is subject to colonization.
You Have Been Colonized
One of the most fascinating aspects of or digestive system is that it is not entirely our own. Right now there are between 500 and 1,000 different species of bacteria living in your digestive system. Some scientists believe that there are 10 times as many microbes living in your body, as there are your own living cells. Others say it is more like three to one. Either way, you are not alone.
Luckily, bacteria are small so this amounts to only around 1%-3% of your body mass. Plus, they are technically outside of your body. Feel better?
So what are they doing there? They are doing what all life does: eating, reproducing, and eating some more, and then dying. But it is through this rudimentary existence that the beneficial – even essential, byproducts that our bodies need to function optimally are created.
Gut Biome and Intestinal Health
Your GI is what scientists call a microbiome. Within this unique, self-contained living environment, the microbes interact with your body, food sources, and each other. These interactions result in an array of symbiotic biochemical reactions that is responsible for not only our digestion but many other aspects of other major systems essential to overall health and wellness.
While the individual organisms may be simplistic, the gut biome is an incredibly complex environment. Researchers are just beginning to understand how this world-within-a-world works.
What they do know is that the gut biome is an integral part of our overall health, with far-reaching implications that affirm much of the work of ancients like Hippocrates and Hildegard, while opening new and exciting frontiers into understanding our health from the inside out.
Bacteria: The Good, the Bad, and the Ugly.
The good (and occasionally bad) news is that bacteria naturally thrive in your gut biome. Your digestive system is a great neighborhood: warm, moist, and full of food, like Florida. And like Florida, once they move in, they don’t leave until they die.
A Diet Rich in Fiber
Hildegard loved fiber-rich spelt, because we can add more good guys to our GI by eating a diet high in plant fiber. The more diverse the better, as our gut flora are a reflection of what we eat. Gut flora can also be specifically supported by eating prebiotic diet foods, those foods that provide the best sources of food for the bacteria already within our system, or those foods already containing live bacteria cultures, called probiotics.
See our post on What is Fermentation for details on how bacteria in your gut thrive as well as 8 of our favorite healthy fermented foods.
But with the good, come the bad. We ingest all kinds of bad things. The same sensitive mucosal layers of our GI that allow for absorption of essential nutrients make us susceptible to foreign invaders.
And if that’s not enough, when deprived of the nutrition necessary – principally, fiber, to maintain GI health, the symbiotic relationship with gut bacteria turns sour, and the good guys get ugly.
When fiber falls short
When starved of fiber, some strains may die off, others adapt to the only other available food source: the mucosal lining of your GI. This triggers a cascade of negative effects including impaired immune function, inflammation, nutrient deficiency, and even hormonal and neurochemical changes affecting mood, energy, and cognitive function.
The “ugly” aspect highlights one of the central challenges of understanding how gut flora affects gut (and overall) health: the good, the bad, and the ugly are not often clearly delineated. The guerrilla warfare in your gut means that there are multiple factions working for their own specific interests and needs, many of which change sides according to the environmental conditions of your GI.
One thing seems clear. Maintaining diversity and balance within your natural (and unique) gut flora is possible. Even more, improving your gut flora is also possible. Both are principally accomplished through your diet.
Just as Hildegard believed, the principle of balance is fundamental when it comes to intestinal health, it is through nutritional and dietary balance that we maintain a healthy balance in our gut biome. And it is through balance in our gut biome that we maintain our intestinal health, and overall health.
What exactly is balance? That is part of the challenge. There is no one-size-fits-all formula for intestinal health. But we do know that there are several species of “good” gut bacteria that account for the majority of the benefits we receive.
Within each species there are several distinct strains, each with unique attributes and beneficial functions. While we have several hundred species, 80% to 90% of our gut bacteria come from only 30-40 species. So the best advice as of now is to eat a wide variety of vegetables and fruits that contain fiber.
This is because individual strains of bacteria within each species flourish in different parts of our digestive tracts where they consume, among other things, the undigested carbohydrates (fiber) from our food. So the wider variety of these fibers we consume, the more (and diverse) types of bacteria we can support.
It is through the consumption of what our own bodies can’t digest that many of the beneficial byproducts are created.
Intestinal health benefits of a bacterial buffet on fiber
Bacteria feed on the carbohydrates we consume, primarily the undigested fiber contained in complex carbohydrates. This is a big part of why fiber intake is an essential part of healthy digestive tract. Without adequate fiber, good bacteria either die off or turn bad by feeding on the lining of the digestive tract, which can lead to auto-immune disorders like ulcerative colitis as well as all varieties of digestive discomfort.
A low fiber diet also opens the door for bad bacteria to flourish, as they are not kept in check by the good guys. To make matters worse, a low fiber and high-sugar diet will foster growth of other bad bacteria and yeast, since these “bad” microbes tend to favor simple carbohydrates (sugar) over fiber.
So how does this all actually happen? The good bacteria consume the fibers that our own digestive enzymes cannot break down. They accomplish this primarily through fermentation, which unlocks the sugars trapped within the fiber and releases many different beneficial byproducts, but some strains also perform other essential metabolic processes.
8 Flora Functions for Intestinal Health
The symbiotic relationship with our GI bacteria is responsible for many essential functions. Here’s why they are the “good” guys:
When bacteria ferment fiber, they convert some of the sugar into acid, which is how your digestive tract maintains an acidic pH. Acidic environments are inhospitable for bad bacteria, so acidity is key for proper immune function.
(2) Short-chain Fatty Acids
The digestive flora creates short-chain fatty acids (“SCFA”). SCFA’s are the primary source of energy for cells in your colon; so more SCFA’s mean that the delicate mucosal cells in your GI are more likely to be healthy. SCFA’s have also been linked with a reduced risk of inflammatory diseases, diabetes, and cardiovascular disease, as they are anti-inflammatory and anti-carcinogenic. SCFA’s are also unique in that they can help regulate hormones in your GI. Higher levels of SCFA have been linked to lower incidence of diet-induced obesity.
(3) Improve Digestion Efficiency
Since bacteria digest what our own enzymes cannot, the result is improved utilization of the previously indigestible carbohydrate. Cells in your GI that are responsible for a wide array of immune responses utilize the additional sugars that are released as a result.
(4) Enzyme Production
Bacteria produce enzymes in your GI that , among other functions, can re-activate hormones like estrogen that are present in your GI, enabling them to be re-absorbed. The re-absorption process is important in maintaining overall hormone balance.
(5) Synthesize Vitamin B and K
Bacteria produce B vitamins, including B12, which is only found in animal flesh (because those animals’ gut bacteria also produce vitamin B12). The bacteria fermentation process also produces Vitamin K (K1 and K2), an essential vitamin for bone mineral absorption and blood clotting.
(6) Metabolize Bile Acids
Bile acids are the acids in your digestive system that break down fats into forms that our bodies convert to energy as well as utilize for the transport of vitamins at the cellular level. Breaking down the excess bile acids keeps bile from migrating where it should not (think GERD or Acid reflux) and it is also an important part of eliminating excess cholesterol and other toxins.
(7) Metabolize Sterols
Sterols are a group of organic chemicals, including cholesterol, which bacteria break down. This helps maintain healthy cholesterol levels by eliminating free cholesterol. And since sterols like cholesterol also play a major role in the production and transport of hormones, a healthy cholesterol metabolism means that your hormones are more likely to be in balance.
(8) Metabolize Xenobiotics
Xenobiotic is a fancy name for the compounds that are not natural to your body. These include carcinogens, drugs, environmental pollutants, food additives, hydrocarbons, and pesticides. Bacteria assist by metabolizing these substances so that they can be eliminated in your waste.