It’s Good to be Dirty – Why You Should Like Bacteria

Today my friend shared an article on Facebook called, “Say Hello to the 100 Trillion Bacteria That Make Up Your Microbiome” or “Some of my Best Friends are Germs.”  It’s a rather lengthy, but very entertaining article, written by Michael Pollan.

As I mentioned in another post, we are not really who we think we are.  Our bodies are only 10% us, the other 90% are them – the bacteria that coat our skin, and live inside our bodies, particularly our intestines.  Whether we like to think about it or not, bacteria are a part of us and have a huge impact on our lives.

Our bodies are homes to 3 types of bacteria: those that hang around because it is a cool (but warm in temperature!) and safe place to be; those that provide a service to us, often in exchange for something we provide them; and a small contingency that are troublemakers, pathogens that can make us sick.  The good bacteria make vitamins and essential nutrients important for our nutrition.  Bacteria also play an important role in training our immune system, making sure our bodies can recognize and fight against bad bacteria and other pathogens such as viruses.

We are beginning to understand that gut bacteria may play other important roles.  Bacteria need food to flourish, therefore they regulate our appetite and digestion.  Japanese people have a common gut bacteria that helps digest seaweed.  In addition to aiding in digestion, bacteria most likely contribute to body size – if gut bacteria are taken from lean mice and given to obese mice, the overweight mice begin to lose weight and vice versa.  But this is just the beginning of the research.

Through projects such as the American Gut Project, scientists are trying to understand how and when we acquire our little friends, what a “normal” population of bacteria might look like and what the consequences are of changing this population.  The research is being galvanized by interesting researchers like Dr. Robert Knight, the head of a lab at the University of Colorado at Boulder that takes thousands of skin, oral and fecal samples from donors and determines the bacterial composition, or microbiome, of the sample.

Although we do not yet know what a “normal” microbiome should look like, scientists are comparing the gut bacteria from diverse populations around the world.  Several facts have already become clear.  Western living (think Europe and North America, not saloons and ten gallon hats) leads to a decrease in the different types of bacteria found in the gut.  This is generally believed to be bad.  Western guts also contain different kinds of bacteria than people in other populations.

This difference in gut bacteria is believed to be due to our “sterile” lifestyle – frequent use of antibiotics changes the type of bacteria in our systems; processing of food destroys food-borne bacteria and our heightened cleanliness makes it less likely that we will come in contact with different types of bacteria.  Some scientists believe that the increases in autoimmune diseases, allergies and asthma seen in Western society are because our bodies are no longer exposed to a variety of bacteria required to train our immune systems.

Dr. Knight and his wife, Amanda Birmingham, are eager participants and zealous believers in their research.  Dr. Knight “samples himself every day” while his wife is “down to once a week” contributions.  Their toddler has also contributed the majority of her diapers to the effort.

Studies of their own microbiomes have led to papers demonstrating that environment plays a big role in determining the types of bacteria found in our guts.  People living together in the same household tend to have similar microbiomes.

Samples from their daughter and other children are helping us learn how we set up a relationship with the bacteria. Beginning shortly after birth up until about 3 years of life, our bodies become colonized with bacteria.  Bacteria that we are exposed to in our environment and that we take in with food take up residence in our bodies.  In fact the first inoculation comes from our mothers – vaginal births lead to babies being exposed to vaginal and intestinal bacteria.  Babies born through cesarean section (C-section) have a different microbiome that more resembles the skin of their parents.  Some people speculate that this difference in gut bacteria is one of the reasons that babies delivered by C-section have higher rates of allergies, asthma and autoimmune diseases.

In fact,  Dr. Knight and his wife worried about this so much, that when their daughter had to be delivered by emergency C-section, they took it upon themselves to collect and smear some vaginal secretions on the baby (sorry folks – I couldn’t leave this tidbit out!).

What do scientists hope this research will lead to?  I think everyone in America has seen Jamie Lee Curtis extolling the virtues of eating Activia, a yogurt with active cultures that help regulate bowel movements.  Our future might actually involve taking care of the bacterial side of ourselves – making sure we support the right gut bacteria to keep our human bodies happy and healthy.

Crude (but effective) bacterial treatments have already begun in patients suffering from Clostridium difficil (C. dif) infections.  C. dif is a bacteria that can take over the normal gut bacteria and cause terrible diarrhea.  It is very difficult to treat a C. dif infection.  Recently, several patients have been cured by fecal transplants.  That’s right – feces from donors with normal gut bacteria are transferred into the gut of patients with C. dif, resulting in a cure.

Hopefully projects like the American Gut Project will lead to a better understanding of our microbiomes and more sophisticated treatments of disease.

If you would like to get involved and maybe find out what your microbiome looks like, you can join in the American Gut Project at this website.

Happy microbe hunting!