10 Creepy Crawlers That Govern Our Bodies

Many of the findings involving the benefits of gut bugs are brand-spanking new, so scientists are still working out how to ethically conduct human trials. It'd be hard to convince an ethical review board, for example, that it's okay to place microbes we associate with depression into the guts of healthy individuals - especially when we're not certain about all the explosive side effects.

What we do know from studying mice is that certain microbes can make their host more adventurous or more anxious depending on the kind of microbe they are.

In a 2011 study, the McMaster group transplanted the gut microbes of easy going, adventurous mice into the stomachs of anxious, timid mice and vise versa. They found the shy mice began to exhibit more "exploratory behavior" after the transplant, while the adventurous mice exhibited "reduced exploratory behavior." 

What does this mean? Well, our little microbes eat what we give them, and depending on the sort of microbe they are, they emit certain chemicals back into our bodies.

Our gut bacteria affect the manufacturing of neurotransmitters (including serotonin) according to Michael Pollan of the New York Times. And in the last few years, scientists have discovered a relationship between a particular strain of bacteria, Oscillibacter, and its link to depression in humans. 

Although this 2014 study suggests correlation and not causation, it is worth noting that our microbes talk to our bodies. 

So, if you're tempted to run for the hills and stock up on all the newly banned antibacterial soaps, think again. These little guys do a lot more than we give them credit for - in fact, they're probably the reason you're alive right now.

The vagina is home to many different kinds of healthy microbes which, when ingested, can help take the place of less-than-ideal microbes and fight off allergies, weight-gain, and depression. "Many people supplement their diets with probiotics," says Lucy Tiven, "but you can also find this type of 'good bacteria' in the human body — specifically in a woman's vagina."

In fact, "most vaginal communities in healthy women are dominated by the lactobacillus species" reports Robinson, Bohannan, and Young in their 2010 study. "Bacteria play important roles...in the production of vitamins and essential amino acids in humans."

When your body comes in contact with these good guys, do the happy dance! They help boost your immune system and fight off the not-so-good bacteria. And without these good guys, you are prone to a host of problems - like asthma, allergies, and other immune system-related diseases.

For example, babies who are born via c-section miss out on the great microbes found in the birth canal. The microbes that colonize c-section children are a mixture of nasty bacteria typically found on the skin and in hospitals, a 2010 study shows, while babies born vaginally reap the benefits of lactobacillus, which aids in milk digestion.

Rob Knight and his wife even inoculated their baby, who was delivered by c-section, by rubbing his wife's vaginal secretions over his child's skin. Formal trials of this practice are currently underway.

"You might only share 10 percent similarity with the person sitting next to you in terms of your gut microbes," explained Rob Knight, professor of pediatrics and computer engineering at the University of California, San Diego. "Although there's just three pounds of those microbes in our gut, they really outnumber us."

So, our essence is essentially non-human?  

Yep, despite the fact that we are 99% identical to the average Joe in terms of human DNA, we are all highly unique based on the vast differences in our microbes. "There are an estimated 3.3 million genes in the total bacteria DNA," reports Science Daily, "which is 160 times the number of human genes."

Could our personalities, quirks, or habits be linked to these little guys? 

Perhaps; and scientists around the world are working to find out more. One way to determine who else is calling your body home is by analyzing what comes out your back end - through your poop. Thanks to cheaper DNA sequencing, curious individuals can donate $99 to the American Gut Project and find out exactly what sorts of microbes are roaming around their GI tracts.

Sound like a weird way to spend a hundred bucks? Maybe, but you'll find out more about why you feel the way you do, which to some, is well worth the dough.

Veterinarians have been studying the connections between microbes and the guts of their patients for years. And luckily the regulations on animals allow vets to try some seemingly off-the-wall tactics to help restore inflamed colons in animals like cows, for example.

Poo tea is one of those tactics, and for some cows, it has helped them restore their gut equilibrium. By taking excrement from healthy cows, vets can concoct a nice heady brew full of microbes to help boost the immune systems of sick cows. After a few rounds of antibiotics to wipe the slate clean, this mixture is administered with the hope that the new, happy microbes will help alleviate digestive symptoms.

In fact, this practice originally started in 4th century China, but they had a better name for it then - yellow soup.

Ingesting poo tea has its drawbacks, though, beyond the obvious gross factor. When the healthy microbes enter the stomach through ingestion, some of the natural acids needed to breakdown nutrients also end up killing the microbes. So, in 2013, the FDA approved more successful treatments involving the brown boom-boom to help treat humans suffering from the no-joking-matter infection, C-diff, which plagues nearly half a million Americans each year.

Fecal transplants allow doctors to take digestive juices from healthy individuals and place them into people suffering from antibiotic-resistant intestinal pathogens.

Think of it this way: when you were born, whether naturally or by c-section, your little body became the hottest real estate on the market, and the microbes that colonized you first have had a lasting impact on your health.

Microbes are like good ground cover, explains Jonathan Eisen in his Ted Talk, and "ground cover around your house can prevent weeds from taking over.” By taking up the best locations (greatest access to food, for example), these microbes not only help your body distinguish between friend and foe, but also help hold down the fort by preventing nasties from moving in.

You want diversity - diversity in your gut microbiota gives your body the best chance to fight off those intruders because "bad bacteria is unavoidable...having good bacteria in our bodies helps stop the bad bacteria from growing and causing disease," says Dr. David Samadi in his article "1 Percent Human, 99 Percent Bacteria." "Our bodies are the homeland, and the good bacteria are the soldiers fighting to protect it."

Without this balance, inflammation can occur; and if you'd like to discover the root of all evil, look no further: inflammation is the body's way of telling you something is wrong. And if this state is constant, it can lead to advanced auto-immune diseases and even cancer.

Your epithelium, which is the uber important lining of your intestines, plays a critical role in protecting your body from infection and inflammation. And guess who keeps your epithelium in tip-top shape? You guessed it - your microbes.

The surface area of your epithelium "is large enough to cover a tennis court," explains Michael Pollan. It "mediates our relationship to the world outside our bodies." And if this tennis court is damaged or undernourished, your protective barrier can't do its job. If this happens, the bacteria and endotoxins (toxic byproducts of certain bacteria) seep into your blood stream and trigger an immune response by causing inflammation. 

This is not good since chronic low-grade inflammation may overtime lead to metabolic syndrome and predispose you to very serious diseases like cardiovascular disease, obesity, Type 2 diabetes, and cancer, a 2007 study finds.  

How do microbes keep your oh-so-important barrier healthy, you ask? Well, epithelial cells like to eat short-chain fatty acids that good gut bacteria produce when they eat their favorite food - plant fiber.