How The ‘Gut Microbiome’ Ultimately Governs Our Health

The concept of ‘hitting’ one’s macronutrients, or even merely calorie-counting, is as pervasive as ever in the fitness world; and, while I don’t deny the importance of tracking macros or calories for body composition purposes, I do believe the macro obsession obscures the bigger picture.

That bigger picture is our gut health, or ‘gut microbiome’.

Don’t worry if you are one of the majority whom has never heard the above notion before, as you should walk away from this post enlightened and equipped to improve your own gut health, and overall wellbeing.

A snapshot of the gut microbiome:

  • Microbiome: micro = small; biome = community of naturally-occurring organisms suited to their given environment
  • Human beings consist of ~70 trillion cells (using a 70kg, 170cm male as reference), with bacteria cells outnumbering human cells by roughly 30%
  • There is thought to be 1000+ different species of microbiota, encoding 10 million genes, in our gastrointestinal tract (GIT)
  • It heavily influences our metabolism, immune cell education, disease prevention, brain function & psychology… To name but a few of its roles. Basically, the gut microbiome impacts ALL parameters of our health, and research is continually mounting to corroborate this idea
  • It can be considered a ‘2nd brain’, perhaps more powerful than our 1st brain; and, collectively weighing 3-5 pounds (thus the same volume)
  • Scientists are still yet to fully comprehend this colony of flora and fauna that exists within humans, but they ARE certain of its significant influence on our health

 

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‘Leaky Gut’ Syndrome (LGS)

LGS is exactly as it sounds: hyper-permeability of the intestinal wall, consequently resulting in ‘leakage’ of undigested molecules, waste products, and toxins, into the bloodstream. Particles that escape the GIT may travel to other areas of the body, including the brain, and trigger global inflammatory effects… which may devolve into disease.

LGS may manifest itself as:

  • Gas & bloating after meals
  • Brain fog
  • Mood swings
  • Multiple food sensitivities
  • Chronic constipation or diarrhoea
  • Chronic fatigue and joint achiness

LGS is also a key culprit in vitamin & mineral deficiencies, as carrier proteins get damaged or filtered into the bloodstream; iron, vitamin B12, magnesium, calcium, folate, zinc and vitamin D are most at-risk.

Now, many of you are probably associating the above symptoms with irritable bowel syndrome (IBS), and you aren’t wrong… But they are not synonymous. IBS & LGS are closely linked, in that they may precipitate one another and often co-exist.

Essentially, IBS is stomach upset (i.e. cramping, diarrhoea, constipation) and LGS is when the gut lining becomes porous.

Our diet is one major contributor to both LGS & IBS, and the good news is that it also serves as the most easily modifiable factor in these conditions.

Scientific literature reports a range of incidence rates of IBS, given the various criteria sets used to diagnose IBS. And while many studies estimate Australia’s IBS incidence to be in the vicinity of ~20%, this is a gross underestimation as only 30% of those with symptoms report it.

More people than not are dismissing abnormal bowel movements, chronic lethargy & brain fog as normal. Perhaps it is fair to say that this dismissive culture has been bred by allopathic medicine (and the countless, dismissive doctors whom constitute it).

The scary thing is that mental illness & obesity have become so prevalent that they too may be termed ‘normal’, in today’s society. 20+% of 16-85 year-old Australians will experience mental illness at some point in any given year, and depression is the #1 cause of non-fatal disability. This is not a coincidence.

 

The Gut-Brain Axis

When I first read of the purported impact our gut microbiota could have on our brain function, I was somewhat sceptical. But after diving deeper into the research, the gut-brain link appears irrefutable.

There is now compelling evidence that gut microbiota can influence humans’ behaviour, with particular note to depressive-like symptoms. The reciprocal gut-brain relationship seemingly takes place at the central nervous system level, with the brain regulating things like gut motility and secretion; and the gut regulating mood.

The main mechanisms by which an altered microbiota state predisposes us to anxiety and depression are believed to relate to cytokine production; and reduced circulating serotonin & tryptophan.

When our intestinal permeability increases, pro-inflammatory messengers termed ‘cytokines’ are released by immune cells, and heavily implicated in psychological disorders, as well as an array of diseases. Depression is more-so a symptom of inflammation than a disease.

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Serotonin is a neurotransmitter (chemical messenger) widely known as the chief commander of mood & sense of well-being. What most people don’t realise is that 80-90% of our total serotonin resides in our GIT.

Gut bacteria (such as probiotics) both produce and respond to the same neurochemicals—such as GABA, serotonin, norepinephrine, dopamine, acetylcholine and melatonin—that the brain uses to regulate mood and cognition.

The translocation of our ‘good’ gut bacteria across the intestinal wall hampers the proportion of the aforementioned neurochemicals, and this has been consistently implicated in depression… As well as deleterious eating behaviours.

How do these microorganisms in our gut lining potentially trigger over-eating and/or voracious food cravings? Well, interestingly, they too crave particular substrates and so when the microbiota balance is thrown out of whack via LGS, this gets fed back to our brain. As an example, the common probiotic bifidobacteria thrives on dietary fibre.

The intricate feedback-loop between our central nervous system (brain) and enteric nervous system (gut) is facilitated by the longest cranial nerve (CNX) in the body, the vagus nerve.

Major takeaway: a happy gut microbiome may indeed stave off anxiety & depressive symptoms, and indirectly reduce cravings.

 

Interesting Misc. Facts

  • Good gut bacteria have demonstrated the ability to convert white (stored) fat to brown (heat-producing) fat. This process increases our basal metabolic rate (BMR; how much energy we burn in a day). More can be read about this in my first article here.
  • Certain studies have reported 84% of IBS patients improving symptomatically after the removal of gluten from their diets. So, while non-coeliac gluten sensitivity (NCGS) is estimated to be ~20 in Australia (determined, again, from various criteria), it is apparent that gluten is pro-inflammatory in a lot of cases.

 

Actionable Steps To Bulletproof Your Gut Wall

  1. As straightforward as this will sound, monitor how you respond to the foods you eat, and eliminate anything that consistently elicits the earlier-mentioned symptoms. And, of course, try to eat simple whole foods 80+% of the time… Your gut will find it much easier to break it down, and greatly reduce your likelihood of LGS. When you get an upset stomach, your 2nd brain is alarming you for a reason – investigate it!
  2. If you are an ‘if it fits your macros (IIFYM)’ fan, feel free to continue with it, but it is risky business trying to fit as many ‘cheat’ meals into your diet as possible. Try to indulge less frequently, and be cognisant of micronutrient intake as well your macros.
  3. Both caffeine & alcohol are gut irritants – try not to binge on either of them too frequently.
  4. Avoid antibiotics (anti = no; biotic = life… death) at all costs. This medicine destroys BOTH bad AND good bacteria in our stomachs, and may permanently alter the gut’s microbiome. View the use of antibiotics as an absolute last resort.
  5. Fermented foods. My personal favourite, which I eat in abundance most days, is natto (fermented soybean, popularised in Japan). Other choices include sauerkraut, greek yoghurt (check the ingredients for cultures such as lactobacillus and bactobifideria) & kombucha.
  6. Sorry ketogenic advocates and paleo lovers, but preliminary data is suggestive of high-fat diets lending themselves to LGS. This is thought to be because fat is a more efficient vehicle for toxin transportation than carbohydrates. I say shoot for balanced macronutrients.

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Happy Summer 🙂

Best,

Jonny.

References:

Bai, Y.-M., Chiou, W.-F., Su, T.-P., Li, C.-T., & Chen, M.-H. (2014). Pro-inflammatory cytokine associated with somatic and pain symptoms in depression. Journal of affective disorders, 155, 28-34.

Balakireva, A. V., & Zamyatnin, A. A. (2016). Properties of Gluten Intolerance: Gluten Structure, Evolution, Pathogenicity and Detoxification Capabilities. Nutrients, 8(10), 644.

Dach, J. (2015). Gut-Brain: Major Depressive Disorder, Hypothalamic Dysfunction, and High Calcium Score Associated With Leaky Gut. Alternative therapies in health and medicine, 21, 10.

Dash, S., Clarke, G., Berk, M., & Jacka, F. N. (2015). The gut microbiome and diet in psychiatry: focus on depression. Current opinion in psychiatry, 28(1), 1-6.

David, L. A., Maurice, C. F., Carmody, R. N., Gootenberg, D. B., Button, J. E., Wolfe, B. E., . . . Fischbach, M. A. (2014). Diet rapidly and reproducibly alters the human gut microbiome. Nature, 505(7484), 559-563.

Elli, L., Tomba, C., Branchi, F., Roncoroni, L., Lombardo, V., Bardella, M. T., . . . Buscarini, E. (2016). Evidence for the Presence of Non-Celiac Gluten Sensitivity in Patients with Functional Gastrointestinal Symptoms: Results from a Multicenter Randomized Double-Blind Placebo-Controlled Gluten Challenge. Nutrients, 8(2), 84. doi: 10.3390/nu8020084

Halmos, E. P., & Gibson, P. R. (2015). Dietary management of IBD[mdash]insights and advice. Nat Rev Gastroenterol Hepatol, 12(3), 133-146. doi: 10.1038/nrgastro.2015.11

Ley, R. E. (2010). Obesity and the human microbiome. Current opinion in gastroenterology, 26(1), 5-11.

Li, X., & Atkinson, M. A. (2015). The role for gut permeability in the pathogenesis of type 1 diabetes–a solid or leaky concept? Pediatric diabetes, 16(7), 485-492.

Luna, R. A., & Foster, J. A. (2015). Gut brain axis: diet microbiota interactions and implications for modulation of anxiety and depression. Current opinion in biotechnology, 32, 35-41.

Tsai, F., & Coyle, W. J. (2009). The microbiome and obesity: is obesity linked to our gut flora? Current gastroenterology reports, 11(4), 307-313.

 

 

 

 

 

 

 

 

 

 

 

 

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