The microbiome: Our body's own planetary system


What if someone told you your body was a mini-planet with many life forms living within it?

It may be hard to envision but, in fact, our body is a microcosm of the very planet we live on.

Picture your body as a miniature Earth. Within it there are trillions of microorganisms representing different species, much like our world. These organisms include bacteria, fungi, parasites and viruses, all coexisting harmoniously – assuming the body is healthy.

This is what the microbiome looks like inside of our bodies.

The term microbiome derives from the words “micro,” meaning small, and “bios,” meaning life. The word “biome” also refers to the environment of an ecosystem. The microbiome hosts anywhere from 10 trillion to 100 trillion symbiotic microbial cells, with the bulk of the bacteria existing in the “ecosystem” of our small and large intestines.

All is good until something goes wrong with the host planet.

Dr. Vijaya Surampudi, an endocrinologist and an assistant professor of medicine in the division of human nutrition at UCLA Health, discussed what happens when those harmonious relationships in the microbiome begin to break down.

“There are studies being done that show how an imbalance of good bacteria and bad bacteria affect how our bodies function,” Dr. Surampudi said.

“When there’s an imbalance in the gut microbial community, there will be experiences of bloating and indigestion. They call this ‘dysbiosis.’ This is when there is a reduction in microbial diversity and less of the beneficial bacteria is observed.”

The imbalance in these cells can be triggered by a bad diet, infectious disease, overuse of medications or other drugs, and a variety of other sources.

Any of these disturbances make the body more susceptible to disease.

Keeping the microbiome healthy

Recent studies have researchers pondering whether the microbiome has “microbial fingerprints” that can identify if a person is susceptible to disease, obesity, symptomatic disorders and other genetic pathologies.

One study Dr. Surampudi identified showed how the microbial make-up in mice was impacted by Fecal Microbial Transplants (FMT) from humans into mice. A fecal transplant is a process by which stool is transferred from a healthy donor into the gastrointestinal (GI) tract of another subject. Fecal transplants are sometimes used to treat Clostridioides difficile, or C. diff, a bacteria that causes severe diarrhea or inflammation of the colon.

Gut microbes are vital for helping us digest nutrients and break down complex molecules in foods like meats and vegetables

Researchers treated the mice with antibiotics and did fecal transplants from human subjects who were obese, average weight and lean. A fecal transplant from an obese person made one mouse obese. The average size person’s fecal matter was inserted into another mouse and the mouse remained average size. A fecal transplant of the lean person was transferred into a third mouse and the mouse became lean.

“It was something about the microbial pattern that affected each mouse’s physical expression,” Dr. Surampudi explained.

Similarly, Dr. Surampudi said, our microbial patterns are affected positively or negatively by our nutrition.

“The thing about the microbiome is we want to keep it as healthy as possible,” she said. “Nutrition is one of the major ways to optimize the microbiome because anything we put in our GI tract will affect the ‘fingerprint.’”

Why our gut matters

A healthy gut means a healthy immune system. When the gut is working at its best, it contains healthy bacteria and immune cells that fight off infectious diseases. A healthy gut can also raise good cholesterol, known as high-density lipoprotein (HDL) and lower bad cholesterol, known as low-density lipoprotein (LDL).

You may have heard the terms prebiotics and probiotics. Both are essential for the overall health of the microbiome and for the gut.

Prebiotics are essentially plant fibers that nurture the growth of healthy bacteria in your gut. They play a huge role in helping the digestive system function optimally. Examples of good prebiotic foods include:

  • Apples
  • Asparagus
  • Bananas
  • Barley
  • Chicory root
  • Cocoa
  • Dandelion greens
  • Garlic

Probiotics are active, or live, bacteria/microorganisms. When consumed, they provide many health benefits to the body such as preventing and treating diarrhea, improving symptoms of irritable bowel syndrome (IBS), reducing allergies and boosting the immune system. However, many probiotic bacteria die on the way through the digestive tract.

Eating probiotic foods can help you ensure you are getting a high enough source of probiotics. Probiotics can be taken in the form of a supplement or can be found in foods such as:

  • Yogurt
  • Kefir
  • Sauerkraut
  • Tempeh
  • Kimchi
  • Miso
  • Kombucha
  • Pickles

Dr. Surampudi said eating a variety of fruits and vegetables can change the “fingerprints” and patterns of the microbiome.

“Eating fermented foods can be really helpful because they have probiotics,” she said. “Fruits and vegetables also have soluble and insoluble fibers.”

The fibers are necessary and can only be fermented by enzymes that exist in the colon. This, in turn, creates short chain fatty acids (SCFA) that are released and lower the pH of the colon. The pH refers to the balance of acidity and alkalinity in the body. Lower pH in the colon hinders the growth of harmful bacteria such as C. diff.

Key to our mood and emotional health

According to Dr. Surampudi, the gut cells are the highest producer of serotonin.

Serotonin is a monoamine neurotransmitter – a chemical molecule used by the nervous system to transmit messages to the muscles – whose roles include influencing mood, emotion, cognition, learning, memory and even physiological events such as vomiting.

“Many researchers are still learning about the brain-gut connection. This raises the question: ‘Do the foods we eat ultimately affect how we feel? So can we then alter our food patterns and feel better?’” Dr. Surampudi said.

To learn more about the microbiome and other nutritional matters, visit the UCLA Center for Human Nutrition.