Above: Image © istockphoto.com/PrettyVectors
My friend is sick. “It’s probably some stomach bug,” she explains. “Reminds me of how much I hate those stupid microbes.” Not long ago, I would have said the same thing. But did you know that your body is home to trillions of microbes? And these bugs aren’t just sickness-causing invaders or casual guests. They actually help shape who you are.
Did you know? Your gut bacteria have about 100 times more genes than the rest of you body. In terms of genetic information, you are more bacteria than human.Thanks to technologies such as DNA sequencing and bioinformatics, researchers have discovered that the human body is more than just a habitat for microbes. You and your microbiome—all the microbes that live in your body—form a complex and interconnected ecosystem!
Most of these bugs live in your gut and belong to four main groups of bacteria. However, the exact composition of your microbiome fluctuates and is unique to you. It is shaped by your genes and your environment, including your diet.
For example, you share the food you eat with your gut bacteria. But until recently, medical researchers thought that bacteria merely lived in your intestines and used the substances you ingest in ways that didn’t really affect you very much.
In reality, your gut bacteria are anything but passive! If they weren’t around, food could only be broken down by your own digestive enzymes, which do little more than chop up food into small bits. But gut bacteria subject food to various forms of fermentation, which creates chemical products that have far-reaching consequences for your health.
Did you know? Crowd-funded projects like American Gut collect microbiome samples from people for DNA sequencing. The long-term goal is to prevent and cure disease by tweaking the microbiome. For instance, some of your resident microbes produce vitamins—organic compounds that your body can’t make itself but that are essential for it to function properly. And when you eat fruits, vegetables, and grains—foods rich in fiber that your own enzymes can’t digest—your gut bacteria pitch in with their own enzymes. Other products of fermentation, including small fatty acids, cross the intestinal wall and enter the bloodstream. As a result, these bacterial by-products have surprising effects on many parts of the body.
Mind-altering microbes: How the microbiome affects brain and behavior
Elaine Hsiao, TEDx Talks
One example is formic acid, which affects the amount of salt returned to your blood from your kidneys and which influences blood pressure. Other compounds, such as butyric acid, act on the immune system and reduce inflammation. From this perspective, researchers have begun to look at whether people with dysfunctional microbiomes—and those who don’t eat much fiber or have little fermentation in their guts—are at greater risk for inflammatory and autoimmune disorders, including Crohn’s disease, irritable bowel syndrome, type1 diabetes, asthma, and multiple sclerosis.
Some intestinal bacteria produce substances that interfere with how body cells respond to insulin, thus preventing the uptake of sugar. The levels of these bacteria are actually higher in people with obesity and type 2 diabetes (both of which are related to insulin insensitivity), suggesting they may be triggers for these conditions.
Even mood and behavior may be shaped by the microbiome! Indeed, gut bacteria make neuro-active chemicals and hormones, which can influence appetite, emotions, memory, and even interpersonal skills.
Did you know? Most of the microbes living in your gut fall into four main groups (phyla) of bacteria: Firmicutes, Bacteroidetes, Actinobacteria, and Proteobacteria.Does this all sound a little far-fetched? Don’t forget that you and your microbiome are partners. Everything you do matters to your resident bugs, including your diet and social habits (which help them spread). So it should be no surprise they evolved mechanisms to control you.
The fact that your body works like an ecosystem has significant implications. Clearly, your well-being hinges on the health of your microbiome, which is why you must ensure that your resident bacterial communities are well balanced, and that your needs and theirs are well aligned. In the future, microbiome evaluations could be as routine as blood tests are today. And maybe one day many medical conditions, from diabetes and heart disease to depression and even autism, could be managed using probiotic yogurts and fecal transplants.
As for my sick friend, she’s not so hostile and dismissive to microbes anymore. She has decided to support her microbiome because she understands its importance. Do you?
How microbes keep us healthy (2015)
Inforgraphic illustrating the different roles played by some of the microbes that make up the human microbiome.