All Disease Begins in The Gut.” – Hippocrates

Research increasingly supports the idea that your gut bacteria are tied to your probability of intestinal disorders and other conditions, like diabetes, obesity, depression, and colon cancer. In this issue of the Altasciences blog, we offer an oversight of the research into how they are linked.

Bacteria in the Body

We have bacteria living throughout our bodies. There are more than 100 trillion bacteria in the human intestinal tract;  300 to 500 different species containing nearly two million genes, and these may have the biggest impact on overall well-being.

The bacteria, or microbes, provide essential nutrients, metabolize dietary fiber into short chain fatty acids, and ensure proper development of the immune system, all critical functions for human health. They line the whole digestive system, mostly living in the intestines and colon, and help digest the food we eat. Along with other tiny organisms like fungi and viruses, they are referred to as the microbiota, or the microbiome.

Each person’s bacterial environment is unique. The mix of bacteria in your body is different from that of anyone else’s. The unique mix is determined partly by your mother’s microbiota — the environment that you’re exposed to at birth — and partly by your own diet and lifestyle.

How Gut Bacteria Affect Disease

The function of the microbiome affects many aspects of your health, from metabolism to mood, to the immune system. It’s thought some kinds of bacteria may protect against illness, while others may increase the risk. People with certain diseases may have an imbalance in the microbial mix, or they may lack a variety of bacteria compared to healthy people.  Some diseases are influenced less by imbalances in gut microbes, and more by how the microbiome digests the food we eat.

The diseases below have been strongly linked to gut bacteria:

Obesity, type 2 diabetes, and cardiovascular disease: 

The microbiota determines things like the level of nutrients you absorb and the number of calories you get. A higher level of gut bacteria can turn fiber into fatty acids, causing fat deposits in your liver, which can lead to something called “metabolic syndrome” - a condition that often leads to type 2 diabetes, heart disease, and obesity.

Inflammatory bowel diseases, including Crohn’s disease and ulcerative colitis: 

People who suffer from these illnesses may have lower levels of certain anti-inflammatory gut bacteria. The exact details are unclear, but it’s thought that some bacteria may activate the immune responses, which attack your intestines and create an environment where these diseases can develop.


It’s thought that the microbiome and metabolic function have an impact on the inflammatory responses that cause rheumatoid arthritis.

Colon cancer: 

Studies show that people with colon cancer have higher levels of disease-causing bacteria in their microbiome than healthy people. There is also evidence that the metabolic by-products of a high-protein diet, digested in the microbiome, contribute to the development of cancerous growth in the colon.

Anxiety, depression, and autism: 

The gut is full of nerve endings that send messages to the brain, via the “gut-brain axis.” Studies have suggested a link between imbalance in the microbiome and disorders of the central nervous system, like anxiety, depression, and autism spectrum disorder.

Medical science hasn’t fully established what a ‘healthy’ colonic microbiota looks like. However, recent studies have identified that the microbial species that live in the mucus layer of the colon, where the bacterial population is most dense, are involved in inflammatory responses.

So how can you positively influence the health of your microbiota, and protect yourself from disease? Follow our blog, as next month we discuss steps you can take to help ensure a healthy gut microbiome.