Is Gut Health Worth The Hype? Everything You Need To Know About The Bacteria In Your Belly ( & More)

I am thrilled to introduce Brittany Allison as my newest student guest blogger.

Brittany Allison is a 4th-year Nutrition student, currently working on her second degree at Ryerson University. She’s a fitness instructor, a cooking enthusiast, and an aspiring Dietitian. She loves to use her knowledge of food, nutrition, and exercise to teach others how to make positive lifestyle changes and help them learn something new about health. Brittany firmly believes that the more you know, the better equipped you are to create healthy habits. With an abundance of misinformation in the media and on the Internet, her goal is to deliver easy-to-understand information to make health accessible.

She is here today to share a very well written and comprehensive piece on the gut health and the gut microbiome that I’m sure you guys will find both informative and intriguing.

Is Gut Health Worth The Hype?

By Brittany Allison 

Health media has been filled with talk of “gut health,” two simple words that have a massive influence on our overall health and wellness. Gut-related buzzwords, such as ‘probiotic,’ ‘fermented,’ and ‘kombucha,’ have become household lingo for many and messages about gut health as it relates to long-term health and weight loss have become popular in both mainstream news and research. Gut health’s rise to fame has brought with it an influx of new supplements, health foods, and products that all claim to fix issues we didn’t know we had. With over 20 million Canadians living with some form of digestive disorder, and $18 billion in healthcare spending dedicated to addressing these issues, it has never been more important to appreciate the role that the bacteria living in our gut can have in dictating our health (1).

Research has found that the health of the bacteria in our gut could play a key role in obesity, diabetes, heart disease, and inflammatory disease. Today’s article breaks down the basics of the gut microbiome, how it can help improve your health and body composition, and explains how your everyday lifestyle and food choices impact your gut.

So what are the Gut and the Microbiome?

Our bodies are made of 40-50 trillion bacteria. A large proportion these bacteria are located in the gut and are referred to as the gut microbiome (2). For a quick biology lesson, the gut is part of our digestive system, which includes our stomach, small intestine, and large intestine. The gut is considered to be part of the “external environment,” which is in contrast to our “internal environment” that makes up the rest of the inside of our bodies (3).

The gut is considered the external environment because it is how external outputs (such as food and water) travel through our body. The bacteria that live in our guts help digest the foods we eat, assist with absorbing nutrients, and determine what nutrients or toxins can pass into our internal environments (4). The microbiome is involved in activities not only regulating the gut, but also regulating our metabolism, body weight, immune function, brain function, and mood (5).

The bacteria in our guts start to multiply before we’re even born and are shaped by many things throughout our lives, including genetics, illness, and modifiable factors, such as stress and diet (5). Because of this, every individual’s microbiome is different.

Diet Diversity, Good Bacteria & Bad Bacteria

Within our guts, there are both helpful and less helpful types of bacteria and the ratio of these “good” and “bad” bacteria can determine different aspects of our health and physique (6). Importantly, the greater diversity of good bacteria we have in our gut, the healthier and more able to fight off pathogens our body will ultimately be (6,7).

The best way to maintain diversity in your gut bacteria is to enjoy a healthy, balanced and varied diet.  Unfortunately, many Canadian’s struggle with overconsumption of processed foods that lack nutrient density, which can negatively impact the variety in our gut bacteria because they do not support their growth as well as whole, nutrient dense foods do (8,9).

The effect that other ingredients, such as artificial sweeteners, have on our gut microbiome is an area that continues to be studied. Although more research is needed, connections between artificial sweeteners consumption and the alteration of the gut microbiome have been made (10).

Improving Gut Health with Prebiotics & Probiotics

Prebiotics and probiotics are food components that foster healthy gut bacteria. You can get plenty of both by consuming a balanced, varied diet.

Probiotics, most importantly Bifidobacteria and Lactobacilli, are live bacteria in certain foods ( such as yogurt, kimchi, kefir, sauerkraut, kombucha and tempeh) that have a role in regulating‘bad bacteria,’ in your gut and can contribute to an improvement to both your digestive and overall health (11,12,13).

Prebiotics, on the other hand, are food components that are not broken down or absorbed during digestion, are fermented by your  gut bacteria, and fuel their growth (11). Certain fiber-containing foods such as fruits, vegetables, legumes, and beans provide prebiotic fibre and can encourage your gut to grow healthy bacteria.

Although both prebiotic and probiotic supplements exist, they are not superior ( and certainly not more nutritious) than acquiring these components from whole foods.

How Does Gut Health Affect Body Weight?

Have you ever known someone that gained and lost weight rather easily and quickly? Or someone that can eat whatever they want without gaining weight? Their gut health may have a role to play.

Both human and animal studies have shown that the types and variety of gut bacteria vary between lean and obese individuals (14,15).

Other studies have shown that those with a healthy gut microbiome did not gain as much body fat, had better levels of glucose and insulin from a high fat and carbohydrate diet, and have lower incidences of type 1 and 2 diabetes (15,16,17). Furthermore, prebiotics have demonstrated the ability to reduce insulin, triglycerides, and cholesterol in obese individuals, which can ultimately improve body composition (16).

There have also been multiple innovative studies conducted in mice that involved taking gut bacteria from obese mice and transferring it into lean mice. The study found that the lean mice gained fat rapidly with no changes to calorie intake or exercise. The obese mice lost fat and quickly became lean. The microbes from the obese mice were increasing energy extraction from the food consumed, which suggests that not only does human gut microbiome respond to body fat level, it may have a role in altering it.

Does Diet & Exercise Affect Gut Bacteria?

Yes. Gut bacteria are highly sensitive to changes in body weight and body fat levels (18,19,20). Over- and under-feeding have both been found to modify the variety and type of bacteria in the microbiome, which can impact the amount of energy that is extracted from food (19,20). When losing weight, the gut bacteria become more efficient at obtaining energy from food, which may partially explain why our metabolisms slow down during periods of dieting.

Antibiotics and gut health

With modern medicine has come the prescription and use of antibiotics. While these medications may be helpful in treating a variety of health conditions, overuse thereof can upset the delicate balance of the gut microbiome1. When this occurs, Candida Albicans, a naturally occurring fungus that usually doesn’t cause any issues, may multiply rapidly, causing overgrowth and infection (candidiasis). This may affect various parts of the body and is the reason for the development of oral and genital thrush. In cases where infections are widespread, once treated, candida die off occurs bringing with it a host of symptoms that make the sufferer feel as though the infection is worsening. These will resolve in time, but still, this is something most would rather avoid.

Antibiotics treat bacterial and not viral infections, so it is important to take them only as prescribed and not overuse them. If you do have to take them, protect your gut health by supplementing with a probiotic1, 2

Here are the references which can be re-numbered IF you use them otherwise should be taken out.



So What are the Take Home Points?

1. The growth of healthy bacteria in your gut may be limited by a diet that is low in a variety of nutrient dense foods.

2. A reduction in gut health is one of the reasons why a poor diet increases your risk for chronic disease.

3. Consume a variety of foods across all food groups to ensure you get ample pre & probiotics in your diet.

Although more research is needed to truly understand the connection between gut health and general health, there is a lot that we do know about this increasingly important topic. Although highly specific recommendations can’t be made just yet, incorporating some of the tips from today’s article will go a long way to improving your gut and overall health for years to come.










  1. Canadian Digestive Health Foundation. (2018). Statistics. Retrieved from
  1. Turnbaugh, P. J., Ley, R. E., Hamady, M., Fraser-Liggett, C., Knight, R., & Gordon, J. I. (2007). The human microbiome project: Exploring the microbial part of ourselves in a changing world. Nature, 449(7164):804.
  1. Anatomy & Physiology. (2013). Digestive system: The alimentary canal and accessory digestive organs. Retrieved from
  1. Groschwitz K & Hogan SP. Intestinal barrier function: Molecular regulation and disease pathogenesis. J Allergy Clin Immunol, 124:3-20.
  1. Food and Mood Center. (2016). What is the gut microbiome? Retrieved from
  1. Claesson, M. J., Jeffery, I. B., Conde, S., Power, S. E., O’Connor, E. M., Cusack, S., … & Fitzgerald, G. F. (2012). Gut microbiota composition correlates with diet and health in the elderly. Nature, 488(7410): 178-184.
  1. Lozupone, C. A., Stombaugh, J. I., Gordon, J. I., Jansson, J. K., & Knight, R. (2012). Diversity, stability and resilience of the human gut microbiota. Nature, 489(7415): 220-230.
  1. Didier Garriguet. (2009). Diet quality in Canada. Retrived from
  1. David, L. A., Maurice, C. F., Carmody, R. N., Gootenberg, D. B., Button, J. E., Wolfe, B.E., … & Biddinger, S. B. (2014). Diet rapidly and reproducibly alters the human gut microbiome. Nature, 505(7484): 559-563.
  1. Suez, J., Korem, T., Zilberman-Schapira, G., Segal, E. & Elinav, E. (2015). Non-caloric artificial sweeteners and the microbiome: Findings and challenges. Gut Microbes, 6(2): 149-155.
  1. International Food Information Council Foundation. (2009). Functional foods fact sheet: probotics and prebiotics. Retrieved from
  1. Macfarlane, S., G.T. Macfarlane, and J.H. Cummings, Review article: prebiotics in the gastrointestinal tract. Aliment Pharmacol Ther, 24(5): 701-14.
  1. Ukhanova, M., Wang, X., Baer, D. J., Novotny, J. A., Fredborg, M., & Mai, V. (2014). Effects of almond and pistachio consumption on gut microbiota composition in a randomised cross-over human feeding study. British Journal of Nutrition, 111(12): 2146.
  1. Walters, W.A., Z. Xu, and R. Knight, Meta-analyses of human gut microbesassociated with obesity and IBD. FEBS Lett,, 588(22): 4223-33.
  2. Turnbaugh, P. J., Hamady, M., Yatsunenko, T., Cantarel, Brandi, L., Duncan, A., Ley. E., & Egholm, M. (2009). A core gut microbiome in obese and lean twins. Nature, 457(7228): 480-484.
  3. Ley, R. E., Turnbaugh, P. J., Klein, S., & Gordon, J. I. (2006). Microbial ecology:human gut microbes associated with obesity. Nature, 444(7122): 1022-1023.
  4. Burcelin, R., Serino, M., Chabo, C., Blasco-Baque, V., & Amar, J. (2011). Gutmicrobiota and diabetes: from pathogenesis to therapeutic perspective. Acta diabetologica, 48(4): 257-273.
  5. Faith, J.J., Guruge, J., Charnonneau, M., Subramanian, S., Seedorf, H., Goodman, A.,Clemente, J., Knight, R., Heath, A., Leibel, R., Michael, R. & Gordon, J. (2013). The long-term stability of the human gut microbiota. Science, 341(6141): 1237439.
  6. Jumpertz, R., Le, D., Turnbaugh, P., Trinidad, C., Bugardus, C., Gordon, J. & Krakoff (2011). Energy-balance studies reveal associations between gut microbes, caloric load, and nutrient absorption in humans. Am J Clin Nutr,94(1): p. 58-65
  7. Cotillard, A., Kennedy, S., Ling Chun, K., Pons, P., Nicholas, P., et al. (2013). Dietary intervention impact on gut microbial gene richness. Nature, 500(7464): p. 585-8
  8. Cerda, B., Perez, M., Perez-Santiago, J., Ternero-Aguilera, J., Gonzalez-Soltero, R. &Larrosa, M. (2016). Gut microbiota modification: Another piece in the puzzle of the benefits of physical exercise in health? Front Physiol, 7(51)
  9. Gravallese, E. M., & Kantrowitz, F. G. (1988). Arthritic manifestations of inflammatory bowel disease. American Journal of Gastroenterology, 83(7)
  10. Zhang, Y. J., Li, S., Gan, R. Y., Zhou, T., Xu, D. P., & Li, H. B. (2015). Impacts of gut bacteria on human health and diseases. International Journal of Molecular Sciences, 16(4): 7493-751
  11. Lam, V., Su, J., Koprowski, S., Hsu, A., Tweddell, J. S., Rafiee, P., … & Baker, J. E.(2012). Intestinal microbiota determine severity of myocardial infarction in rats. The FASEB Journal, 26(4): 1727-1735.