Jonathan Ross by Jonathan Ross

It’s funny how often we hear the expression "go with your gut" when trying to make a big decision. Our "gut instinct" is our intuition—a vibe or feeling we get that comes from many sources, including the sum of our experiences and wisdom. But our real gut is even more powerful—in fact, it is connected to overall health, disease and even mood, and it is, in turn, affected by just about everything we do.

The Gut Microbiome: The Big Boss

Your gut microbiome consists of trillions of bacteria, fungi and viruses, the majority of which are ideally healthy and beneficial. The collection of microbes that live in and on the human body is known as the microbiota, while the microbiome refers to the complete set of genes within these microbes. Microbial genes significantly influence how the body operates. Each of us has a unique microbiota and a unique microbiome, which is determined by your genes, geography, health status, stress, diet, age, gender and everything you touch. And, because those factors vary widely, the make-up of the microbiome is constantly changing.

Although bacteria account for most of the mass of the microbiota, viruses are actually the most abundant inhabitants. We tend to think of viruses as harmful, but that's not always the case. The viruses found in the gut typically infect gut bacteria cells, but they don't necessarily harm them. Rather, they have a symbiotic relationship. Viruses can quickly transfer genes—beneficial genes. So, if new bacteria are introduced to your gut, either through diet or probiotics, the viral cells can help the bacteria thrive by transferring the genetic code (Neu and Rushing, 2011).

The role of the microbiome is so central to the body's operations that it essentially acts as an organ, impacting aging, digestion, the immune system, mood and cognitive function.

Research has also revealed the important role the microbiome has on mental health. There is a complex relationship between the gut and brain, called the gut-brain axis (GBA), and there may be a connection between poor gut health and depression. The microbiota interacts with the central nervous system to regulate brain chemistry and mediate stress response, anxiety, and memory (Carabotti et al., 2015).

The Gut–Disease Connection

A healthy, balanced gut microbiota promotes a strong immune system and lower levels of chronic inflammation. Conversely, an unhealthy microbiota has been linked to obesity, asthma, allergies and autoimmune disorders, such as celiac disease, type 1 diabetes, inflammatory bowel disease and rheumatoid arthritis. Increasingly, chronic inflammation is also thought to be a root cause of cardiovascular disease, type 2 diabetes and some forms of cancer.

Fecal Transplant Cures Clostridium Difficile Enteritis Infections

People with the hospital-acquired infection Clostridium difficile enteritis (C. diff.) have begun to receive transplants of feces from healthy individuals to regenerate their intestinal microbiomes. This shocking yet highly successful procedure has been shown to be more than 90% effective in curing patients of C. diff., which has become highly antibiotic resistant. Fecal transplants work so powerfully because they reintroduce healthy bacteria immediately into the colon. The effect is like taking the world’s most powerful probiotic.

Athlete Gut Check

Irish researchers recently examined the effect of the microbiome in elite sports professionals. The research, which included 40 Irish rugby players from the national squad, found that being physically active may encourage beneficial strains to thrive in the gut. The study shed fresh light on how physical fitness boosts gut bacteria by demonstrating that the microbiome of an athlete is primed for tissue repair and aids in the high rate of cell-turnover evident in elite sports (Barton et al., 2017).

Healthy Gut, Happy Everything

Many of these findings about the gut microbiome are shocking and unexpected, but this next part is not. How do you promote and maintain a healthy gut? How do you create and nurture a stable and diverse community of intestinal microbes? It's simple: Eat healthy and exercise. Consume an array of fiber from a diet rich in vegetables, fruits, whole grains and pulses (beans and lentils), which are rich in "prebiotic" fiber. This is a type of dietary fiber that escapes digestion in the small intestine but is fermented by the types of bacteria you want to have hanging around in your colon. You can also take a supplemental probiotic and consume fermented dairy products such as yogurt and kefir (unsweetened of course).

The gut seems to be a determining factor in nearly every component of a healthy or unhealthy life. As a result, as health and fitness professionals, it is more important than ever that we do all we can to ensure everyone we lead toward health is combining sensible eating patterns with regular physical activity rather than choosing one or the other. Further, it is essential to keeping coaching clients to make better health choices regarding sleep, stress, and any other related aspects of healthy living.



Barton, W., et al. (2017). The microbiome of professional athletes differs from that of more sedentary subjects in composition and particularly at the functional metabolic level. Gut, doi: 10.1136/gutjnl-2016-313627

Carabotti, M. et al. (2015). The gut-brain axis: Interactions between enteric microbiota, central and enteric nervous systems. Central and Enteric Nervous Systems,  28, 2, 203-209.

Neu, J. and Rushing, J. (2011). Cesarean versus vaginal delivery: Long-term infant outcomes and the hygiene hypothesis. Clinics in Perinatology, 38, 2, 321-331.


Looking to expand your nutrition knowledge and learn how to translate that information into actionable lifestyle changes for clients and patients? Learn more with ACE’s Fitness Nutrition Specialist program.

Get more and save more
with CEC Power Pass

CEC Power Pass gives you unlimited access to the
knowledge you need to be your best.

See How