Your Gut - the epicentre of your health - Part I
“All disease begins in the gut”
Hippocrates
Our body is like a planet inhabited by mind-boggling numbers of micro-organisms. The diversity of this life on every one of us is quite amazing. Our digestive system, our skin, eyes, lungs are happily coexisting with trillions of invisible lodgers, making one ecosystem of macro and micro life. It is a symbiotic relationship where neither party can live without the other.
Different communities of microbes populate different areas of our body, not just our gut. Each community is comprised of different microbes. Collectively, these communities create our microbiome and it turns out this magical kingdom may be the most important organ in your body. Bacteria in your microbiome outnumber your own cells 10 to 1, and bacterial genes outnumber your own genes by 10,000 to 1.
While we share about 99.9% of our genome with the rest of humankind on earth, our microbiomes can be up to 80-90% different. Therefore, you can think of your microbiome as your own personalised microbial fingerprint, different from any other human being in the world.
The largest colonies of microbes live in our digestive system. A healthy adult on average carries 1.5 – 2 kg of bacteria in the gut, roughly the same weight as the human brain. That is roughly 100 trillion microorganisms, with 500 - 1000 different species in one person (1), and no two people having the same. This is called your gut microbiome. All these bacteria live in a highly organised micro-world with certain species predominating and controlling others.
Throughout its entire length, the gut milieu changes and provides many growing conditions. Oxygen and acidity are two important requirements for their growth, with some bugs tolerating high acidity with low oxygen levels, others needing the opposite. The distribution of bugs in the gut is dependent on the particular growing conditions. And the number of functions they fulfil in our bodies is so vital to us, that if our gut was sterilised, we would probably not survive.
What does a healthy gut look like?
Your gut contains several classes of organism including bacteria, fungi, viruses, parasites. Most of these microbes are found in the large intestine, with relatively few in either the stomach or small intestine.
Although there is no such thing as a “normal” gut, there are specific microbes and patterns of colonisation that are favourable.
There are 3 types:
Beneficial (normal, healthy, friendly, ‘commensal’)
Opportunistic (just as it sounds – they proliferate as soon as the Beneficial are depleted, and need keeping firmly under control)
Pathogenic (the baddies) – these can be bacterial, viral, yeasts or parasitic.
As long as the beneficial bacteria outweigh the pathogenic and opportunistic bacteria, your gut microbiome will be in good shape. Animal experiments that involved sterilising the gut have shown the gut and the health of the animal disintegrates. In a human, the absence of good bacteria always coincides with bad bacteria getting out of control, leading in turn to the development of disease. Such a state of imbalance between the various organisms in the gut is called ‘gut dysbiosis’. One of the most common imbalances is H (Helicobacter) Pylori overgrowth, which can cause chronic gastritis, ulcers, stomach pain and bloating. Yeast overgrowth can also seriously disrupt things, and Candida is the most common yeast, fuelled through an inflammatory diet that is high in sugar and processed foods. Parasites are microbes that can enter your body via contaminated food or drink and overgrowth can lead to all the symptoms listed in this article below. Most of us, particularly those who travel, have at least one parasite; but some are much worse than others and need killing off.
The more diverse your gut bugs the better – high diversity is an excellent indicator of a healthy gut. (2) Low bacterial diversity has been reproducibly observed in people with inflammatory bowel disease, arthritis, type 1 and type 2 diabetes, coeliac disease, obesity, and arterial stiffness. This is because low diversity reduces the resilience and robustness of your gut.
An unhealthy and unbalanced microbiome can contribute to heart disease, cancer, diabetes, obesity, autoimmunity, dementia, allergies, asthma, fibromyalgia, Parkinson’s, skin disorders (acne, eczema and psoriasis), not to mention all the digestive disorders including irritable bowel, acid reflux or colitis.
What are all these microbes doing, and why do we need them?
The gut microbiome does things we humans can’t. The microbes protect us from infection, maintain insulin sensitivity thus keeping our blood sugar stable, produce healthy hormone-like chemicals which regulate our energy, control our brain health through the production of neurotransmitters, regulate and maintain our immune system (70-80% is located in our gut), play an important part in food digestion and absorption, produce vitamins (this is why when our gut flora is damaged we have nutrient deficiencies) and maintain motility (keeping food moving through our system). Here is some detail on the 4 biggies:
Protection of gut lining
Our digestive tract is a 30+ ft tube, open to the outside world at both ends, providing a perfect entrance for harmful things to enter our bodies. We ingest plenty chemicals and toxins every day. How do we survive? Because the whole of the digestive tract lining (the epithelium) is coated with a bacterial layer that provides a natural barrier against pathogenic invaders, undigested food, viruses, toxins and parasites. It also maintains the tight junctions between the lining cells to stop all this bad stuff getting into our bloodstream. If our beneficial bacteria are not on top form, then the sacred lining of the gut becomes unprotected and open to invasion by anything that comes along, causing inflammation and intestinal permeability, known as ‘Leaky Gut. (see Part II).
We are what we absorb, not what we eat
Apart from protecting the gut wall, our gut microbes take an active part in the very process of digestion and absorption, so much so that the normal digestion and absorption of food is impossible without a well-balanced gut microbiome. This population of organisms can digest protein, ferment carbs and break down fats and fibre. Via a very carefully controlled transport regulation process, it makes sure that vital nutrients are transported through the gut wall into the bloodstream and off to our cells. If your microbiome is out of whack, even the best foods and supplements in the world won’t be broken down and absorbed.
Chemical factory
Our gut microbes have over 200 million genes! Genes make stuff, and our gut bugs, controlled by their genes, produce hormone-like chemicals which have a huge range of functions throughout our body. But it all depends on your consumption of fibre.
Our beneficial bacteria digest (actually, ferment) fibre in our colon, and create incredibly valuable biproducts call ‘short-chain fatty acids’ (SCFAs). (I know this sounds too detailed but hang on in there – it’s really important you understand this). These SCFAs cross the gut lining and are absorbed into the blood stream, from where they interact with all our organs and help control our metabolism.
they help to regulate sugar processing in the liver, thus reducing insulin resistance (key to long term health) (3).
they help in the production of release of ghrelin and leptin which tell us if we are hungry or full. If we are not told we are full by our hormones, we just keep eating. A higher production of them has been shown to correlate with lower obesity (4).
fat deposits and cholesterol metabolism are controlled by insulin and the liver, but SFCAs are intimately connected with this process.
they create antioxidants which mop up free radicals that cause inflammation
they promote the development of a robust immune system. SCFAs have been confirmed to contribute to the maintenance of the immune balance of the kidneys, the lungs, the central nervous system and the eyes (5)
One of these SFCAs is called butyrate. As far as I am concerned this is the King of the SFCAs. It plays a key part in the creation and health of the epithelial cells (the cells of the gut lining) themselves and is also the main energy source for the cells that line the colon (colonocytes). Absent butyrate, the gut lining will start to degenerate, which damages its ability to digest and absorb nutrients. A plentiful supply plays a very meaningful role in preventing colon cancer. Butyrate has also been shown to slow the progression of Parkinson’s and Huntington’s diseases in animal models (6) (7).
Most of us are aware that fibre is good for us. Fresh fruit and vegetables, whole grains, nuts and seeds, beans and pulses are all good sources of fibre, and there is a long list of benefits from regular consumption. Dietary fibre can’t be digested by the human gut without the help of beneficial bacteria. But when these good bacteria are damaged and can’t “work” the fibre, the fibre itself can become dangerous for the digestive system, providing a great habitat for the bad bacteria, causing bloating and aggravating the inflammation in the gut wall. This is when your practitioner should recommend a low-fibre diet.
Brain health
Did you know you had a brain in your gut? New scientific developments are showing us just how critical the gut microbiome is for brain health (8). Your gut bugs communicate directly with your brain in two main ways: via chemicals and via nerves.
The hormone-like chemicals (neurotransmitters) get to the brain via the blood stream. These affect brain function such as reward, stress response and thinking. Let’s take seratonin as an example, one you have all probably heard of. You need serotonin to feel good. It moderates your appetite, your sleep, your mood, your sexual desire and your memory. 70-80% of serotonin is made in your gut, and the gut microbes are intimately connected to its production. Happy gut, happy you.
The nerve connection between the gut and the brain is via the vagus nerve – the longest nerve in your body, meandering as it does through the entire abdomen, reaching all parts of the gut before it connects up to the brain. Messages constantly travel along this nerve in both directions. This communication system is called the gut-brain axis, and the messages that are sent back and forth are controlled by the gut microbes. Yes, your brain is, to a large extent, controlled by your gut (9).
What causes gut dysbiosis?
Poor food choices
Gluten is probably the biggest culprit. Modern wheat has a powerful inflammatory protein called gliadin that can damage the gut lining and cause Leaky Gut (see Part II). Two-thirds of UK wheat and barley today is sprayed with weed killer glyphosate (the active ingredient in the controversial herbicide Roundup) at harvest to stop it drying out. Aside from being a known carcinogen, glyphosate has been found to harm your microbiome. (10)
Refined carbohydrates: sugar and starch. The bad guys love it just like you do, and it causes the overgrowth of toxic bacteria and yeast – which is why you feel bloated after a meal. (11)
Refined, highly processed oils - sunflower oil and vegetable/seed oils generally. These are inflammatory. (Omega 3 fats do the opposite – fat is NOT the enemy!)
Processed foods, containing additives and preservatives. Some of the worst are the thickeners and emulsifiers in most processed food, including carrageenan and gums.
Artificial (synthetic) sweeteners. Despite being “generally recognised as safe” by regulatory agencies, there is clear evidence that these disrupt the balance and diversity of your microbiome. (12)
Alcohol. I am afraid alcohol wreaks havoc through your body in multiple ways, but in the context of this article, it does direct damage to the gut lining causing nutritional deficiencies through malabsorption.
Antibiotic overuse is a pervasive problem that is rapidly changing the human gut microbiome. Just a single course of antibiotics causes rapid and long-lasting changes (13). Antibiotics annihilate beneficial gut microbes, while creating space for opportunistic pathogens to gain a hold. Overuse has also contributed to the meteoric rise in antibiotic-resistant bacteria, which are responsible for serious infections such as MRSA (14).
Common non-antibiotic pharmaceutical drugs. Heartburn medications (proton-pump inhibitors, or PPIs) have a significant adverse effect on the gut microbiome, decreasing diversity and increasing opportunistic and pathogenic bacteria (15) (16). Antifungal drugs will skew the composition too, leading to colonisation by drug-resistant fungi (17). And lastly antipsychotic drugs deplete beneficial bacteria, particularly the important, anti-inflammatory bacterium Akkermansia. (18)
Chronic stress doesn’t just detract from your quality of life; it also harms your gut microbiome. Stress affects the microbiome by altering the oxygenation of the gut, which changes which microbes can survive there. Secondly it causes the release of catecholamines (adrenaline, noradrenaline and dopamine) which encourage the growth of gram-negative bacteria (19). These bacteria cause the more serious infections, that are in turn difficult to treat because they are resistance a) to certain antibiotics and b) to being ingested by white blood cells of our immune system. They also give off endotoxins which increases the severity of symptoms.
Lack of sleep – sleep deprivation and circadian rhythm disruption are often overlooked but crucial factors that influence the gut microbiome. In animal studies, circadian disruption caused by a reversed light/dark cycle has been found to alter the gut microbiome significantly. In humans the equivalent is shift work and may explain why so many shift workers have metabolic dysfunction (20).
Hidden existing chronic infections – long term infections can go undiscovered for years, having no noticeable symptoms, doing serious harm to gut health. Stool testing can uncover any existing infections (21).
What are the symptoms of ‘gut dysbiosis’?
Because the functions of a healthy gut microbiome are so diverse, any number of symptoms can appear due to dysbiosis. But sometimes there are none.
Here are several of the most common:
Bloating, gas, abdominal pain, diarrhoea, constipation.
Brain fog, anxiety, depression
Skin problems – eczema, psoriasis, acne, rashes, hives
Heartburn/acid reflux
Feeling of fullness with food just sitting in stomach
Joint pain
Fatigue
Pause for breath. Part II will cover:
What does ‘gut dysbiosis’ cause in the short term?
What foods can exacerbate this situation?
How does gut dysbiosis impact our health in the long term?
How do we heal our gut and keep our microbes happy?