Once upon a time, the gastrointestinal tract (or gut) was thought to just be a channel for food to enter and exit the body. My, how things have changed! In recent years, there have been increasing studies into the correlation between gut health and a person's overall physical and mental health.

The health of the gut microbiome has been linked to several diseases, ranging from obesity and cardiovascular disease to depression and anxiety. So, what exactly is gut health and what on earth is the gut microbiome? Before we get to the good stuff, let’s break down what it all means…

• Gut microbiome: An ecosystem of trillions of microorganisms (mainly bacteria) that live in the intestinal tract. These bacteria and the body’s immune cells are in constant communication, particularly when an immune response is required – 70% of the immune cells are located in the gut and the bacteria in the gut help these immune cells identify bad bacteria.
• Microbiome: The combined genetic material of the microbiota.
• Microbiota: Different types of microorganisms living in a specific environment - where the microbiome refers to microorganisms and their genes, microbiota refers to just the microbes themselves. This includes bacteria, fungi, viruses, etc. Bonus fact: Together they weigh around 2kg, which is more than the weight of the brain. Most of these are found in the gut, but some are found in the skin and genitals.
• Microbial diversity: Different species of microorganisms within a certain habitat (the human body). High microbial diversity is linked to good gut health however if someone has low diversity, it’s considered microbial imbalance (a.k.a. bad gut health).

Having good gut health is linked to improved immunity, bone health, energy levels, and mental state alongside a reduced risk of some cancers, lower inflammation in the body, weight management and more.

On the other end of the spectrum, poor gut health is linked to obesity, insulin resistance, leptin resistance (the satiety hormone), high cholesterol, increased inflammation, mental conditions such as depression and anxiety, and now for the big one(s) – diseases such as IBS, Crohn’s disease, colon cancer, metabolic syndrome, type I and type II diabetes, cardiovascular disease allergy, obesity, asthma, eczema and autism.

Okay, now that we’ve been through the what, let’s get to the how (to improve your gut health).

1) Boost your prebiotics

Probiotics are live microorganisms that aim to maintain or improve good bacteria in the body. Prebiotics are types of plant fibre and encourage the growth of probiotics in the gut, a.k.a. food for probiotics. Prebiotics are found in fibrous foods like fruits, vegetables, nuts, seeds, legumes and grains.

One way to improve your gut health is to pack more fibre into your diet. Consider a weekly fruit and vegetable box delivery service – you’ll have access to a range of fresh, seasonal produce and can avoid the supermarket queues. You can also look at incorporating extra fruit and veg into your existing diet, like grating veggies into your pasta sauce or adding a fruit smoothie to your day.

2) Manage stress

Ok, this one’s easier said than done, but chronic stress can wreak havoc on the gut! When our fight or flight system kicks in, digestive function takes a backseat. When we’re stressed, gut motility (movement of food through the body) and digestive enzyme secretion decreases, and constipation or diarrhoea can occur.

Stress is a natural part of life, so it’s not so much about eliminating it but finding ways to manage it. Try using guided meditation apps like Insight Timer or Calm, find coping mechanisms that work for you such as drawing or cooking, go for a walk outside, give your pet a cuddle – whatever floats your boat.

3) Reduce alcohol and sugar intake

The key with this one is to reduce, not eliminate (because where’s the fun in that?). It’s easy to fall into the habit of a glass of wine or two after dinner, alongside some chocolate and lollies – hey, it’s been a rough day ok!

Alcohol can cause inflammation and depletes immune cells. Sugar can feed bad bacteria – with their powers combined, they definitely do a number on your gut. Try incorporating booze-free nights each week (hello mocktails) or filling your glass halfway instead of to the top. When it comes to the sweet stuff, it’s no secret that refined sugar can negatively impact our health if consumed in excess. Satisfy your sweet tooth with fresh/dried fruit or some organic dark chocolate.

4) Avoid artificial sweeteners

Artificial sweeteners are some of the most common additives used in food production. You’ll find them in chewing gum, ‘sugar-free’ energy and soft drinks, protein powders and diet foods. Look out for numbers E951 (aspartame) and E955 (sucralose). There is now increasing evidence that indicates the harmful effects that artificial sweeteners have on the body, the gut in particular.

Animal studies indicate that artificial sweetener consumption (particularly sucralose, aspartame, and saccharin) can negatively alter gut microbiota. Recently, a large study led by Brian Hoffman at the University of Wisconsin exhibited a link between artificial sweeteners and poor health outcomes. Artificial sweeteners seem to alter the gut microbiome in mice and humans and induce glucose intolerance (which results in higher than normal glucose levels). “In our studies, both sugar and artificial sweeteners seem to exhibit negative effects linked to obesity and diabetes”.

5) Consider if you actually need a probiotic supplement

Probiotics are:

• Found in some fermented foods
• Added to foods
• In supplements

Probiotics have many roles including synthesis of B vitamins and vitamin K, secretion of antimicrobial substances, modulation of the immune system, and prevention of pathogens invading the gastrointestinal tract. Typically, probiotics do not actually live in the gut; they pass through the gut and interact with immune cells and microbes in the gut along the way, conferring a benefit as they do. This is why probiotic supplements are only beneficial if taken consistently.

Probiotics are popular nutritional supplements and although they only make up 3.6% of all supplements sold in Australia, the rate of growth is 15%, much higher than the total supplement category at 8.4%. Globally, the probiotic supplement industry is worth $51 billion AUD. The evidence on the efficacy of probiotics is mixed, it seems that for the healthy person, there may be little benefit; however, for those with dysbiosis and a poor diet, there may be merit. There are many different strains of probiotics found in supplements. Commonly used strains are Lactobacillus acidophilus, Saccharomyces boulardii, Lactobacillus rhamnosus and Bifidobacterium bifidum. Each has a different function, so results are reliant on using the correct strain for the condition. Many people may be taking probiotics with no benefit.

References

Bressa, C., Bailén-Andrino, M., Pérez-Santiago, J., González-Soltero, R., Pérez, M., Montalvo-Lominchar, M. G., … Larrosa, M. (2017). Differences in gut microbiota profile between women with active lifestyle and sedentary women. PloS One, 12(2), e0171352. https://doi.org/10.1371/journal.pone.0171352

Carding, S., Verbeke, K., Vipond, D. T., Corfe, B. M., & Owen, L. J. (2015). Dysbiosis of the gut microbiota in disease. Microbial Ecology in Health and Disease, 26, 26191. https://doi.org/10.3402/mehd.v26.26191

Flint, H. J., Scott, K. P., Louis, P., & Duncan, S. H. (2012). The role of the gut microbiota in nutrition and health. Nature Reviews Gastroenterology & Hepatology, 9(10), 577–589.

Flint, Scott, Louis, & Duncan, 2012 - Graf et al., 2015 - Scott, Gratz, Sheridan, Flint, & Duncan, 2013 - Guarner, 2015 - Bressa et al., 2017.

Gibson, G. R., Probert, H. M., Loo, J. Van, Rastall, R. A., & Roberfroid, M. B. (2004). Dietary modulation of the human colonic microbiota: updating the concept of prebiotics. Nutrition Research Reviews, 17(02), 259. https://doi.org/10.1079/NRR200479

Healthdirect. (2018). High fibre foods and diet. Retrieved from https://www.healthdirect.gov.au/high-fibre-foods-and-diet

Hoffmann, B., Ronan, G., & Haspula, D. (2018). The Influence of Sugar and Artificial Sweeteners on Vascular Health during the Onset and Progression of Diabetes. The FASEB Journal, 32(6), 2979–2991. https://doi.org/10.1096/fj.201700993R

Nettleton, J. E., Reimer, R. A., & Shearer, J. (2016). Reshaping the gut microbiota: Impact of low calorie sweeteners and the link to insulin resistance? Physiology & Behavior, 164(Pt B), 488–493. https://doi.org/10.1016/j.physbeh.2016.04.029

Ottosson, Filip LU ; Brunkwall, Louise LU ; Ericson, Ulrika LU ; Nilsson, Peter M. LU ; Almgren, Peter LU ; Fernandez, Céline LU ; Melander, Olle LU and Orho-Melander, M. L., Ericson, U., Nilsson, P. M., Almgren, P., Fernandez, C., Melander, O., & Orho-Melander, M. (2018). Connection between BMI-Related Plasma Metabolite Profile and Gut Microbiota. Journal of Clinical Endocrinology and Metabolism; 103(4), Pp 1491-1501 (2018), 103(4), 1491–1501. Retrieved from https://lup.lub.lu.se/search/publication/2a36c1bf-9bb3-4633-b6e3-083ca1ce9d2c

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