Crohn's disease and the gut microbiome

Bacteria, viruses and other microorganisms may not make you think of good health. But the trillions of microscopic organisms that live on and in your body play a vital role in keeping you well.

Research shows that individuals with inflammatory bowel disease (IBD), such as Crohn's disease (CD) and ulcerative colitis, have an altered gut microbiome compared with those who don't have IBD. The scientific world is continually expanding its knowledge about the microorganisms in the gut and discovering new insights that will hopefully lead to new approaches of treating Crohn's disease.

The microbiota is a collective term for the bacteria, fungi and viruses that live on and in the human body. A microbiome includes microbiota and their genes. The gastrointestinal (GI) tract, skin, mouth, lungs, urinary tract and other parts of the body have distinctly different microbiomes. Like a fingerprint, microbiomes are unique to each person. But unlike human tissues and cells, microbiota are dynamic — they change in response to external and internal factors.

The largest population of microorganisms lives in the gut and is called the gut microbiota. The microorganisms in your gut influence everything from digesting food to regulating the body's stress response. A healthy gut contains a rich diversity of microbes. When your gut microbiome is healthy, it helps keep your body functioning well by:

• Building and regulating the immune system.
• Protecting the GI tract from harmful bacteria and viruses.
• Digesting food and extracting nutrients.
• Producing vitamins the body can't make alone.
• Communicating with your brain and regulating the stress response.
• Producing health-promoting short-chain fatty acids.

A gut microbiome is considered not healthy when it lacks diversity in microbiota and is out of balance. Research shows an association between certain chronic health conditions — such as IBD and rheumatoid arthritis — and a gut microbiome that is out of balance. It's not clear, however, if an altered gut microbiome is the cause or an effect of the health condition.

While researchers continue to explore the connections between Crohn's disease and the microbes in the GI tract, there are lifestyle habits and choices you can make that promote a healthy gut microbiome.

• Enjoy a diverse diet. Eating a wide variety of foods is associated with a healthy gut microbiome.
• Eat plenty of fruits, vegetables, whole grains and beans. These foods contain fiber, which serve as food for the bacteria living in the GI tract.
• Eat fermented foods. Foods such as yogurt, sauerkraut and kimchi contain beneficial bacteria that can support gut microbiota.
• Keep added sugars to a minimum. Diets high in sugar are associated with a gut microbiome that's not healthy.
• Maintain a healthy weight. Being obese may reduce the bacteria that provide nutrients and protect the gut from pathogens.
• Stay active. Exercise increases the beneficial bacteria and overall variety of microbes in the GI tract.

Factors that lead to a gut microbiome that is not healthy and out of balance include:

• Antibiotics. Overuse of antibiotics reduces the diversity and quality of gut microbes, potentially causing GI issues.
• Poor diet. A diet that's low in fiber or high in animal protein and fat is associated with a decreased variety of bacteria in the gut and a reduction in beneficial bacteria.
• Aging. Although gut microbiota are relatively stable throughout adulthood, aging is associated with a decline in the diversity of gut microorganisms.
• Medications and the environment. Some medications and exposure to toxins in the environment can negatively impact the gut microbiome.

Much research is underway examining the role that the gut microbiome plays in developing and treating Crohn's disease. Although many advances have been made, more research is necessary to understand the complex relationship between the microbiome and disease. Until then, practicing healthy lifestyle habits can help keep your gut microbiome healthy too.