doctor with intestinal system picture
Understanding the Microbiome

Your Gut and Your Immune System

Your body is teeming with microbes, especially in what scientists call your gut. That’s your stomach and intestines. But these aren’t the bacteria that make you sick. The trillions of organisms work together in ways we are only now starting to understand.

You have 200 to 500 different bacteria at play in your gut, making up your unique microbiome. These microbes are part of your immune system, helping fight off sickness and disease. Some of the earliest research on gut bacteria involved intestinal conditions like Crohn’s Disease or Irritable Bowel Syndrome (IBS). In most people, the systems work smoothly to remove waste from the body. For people with problems like IBS, the microbiology of the intestines seems to be out of whack.

The University of Utah Genetic Science Learning Center explains how our microbiome comes to be.

“Before birth, we’re all more or less sterile—we have no microbes. Within a few years, we’re covered in thousands of different species of microbes, and they colonize every millimeter of the body that’s exposed to the outside world. By the time we enter kindergarten, we have vastly different populations living in the different habitats around our bodies. Even as adults and into old age, our microbiota continue to shift.”

Bacteria in your body are carefully balanced. When you take antibiotics to kill one kind of bacteria that is causing a sickness, the whole system can get out of whack. That’s why doctors and scientists are interested in learning all they can about gut microbes. If a strain of bacteria is introduced to target a disease, it doesn’t have the side effects of drugs.

New research from Harvard Medical School looked at individual microbes, not just the overall gut environment. They studied 53 different gut bacteria to see how they were involved in immunity. What they found was a highly complex system of interactions. “Some bacteria boosted the activity of certain cells, while others dampened the activity of the very same cells,” explains their news release. The combination of bacteria seems to work in harmony to create balance, including with genes having to do with inflammation.

Maintaining Gut Biome Health

Knowing about the world of microbes inside you, what can you do to keep things in balance?

Antibiotics are one of the key disruptors to your gut bacteria. A common side effect of taking one is diarrhea—a key sign that things are imbalanced in your intestines. Antibiotics are an important tool to fight disease, but you should talk to your doctor when she prescribes one. Is it necessary or something you can do without? Antibiotics attack only bacteria, so you should not take them for a virus like the flu.