ABC News correspondent, Katie Moisse reported an interview, entitled "The Inns and Outs of Gut Bacteria," 2 May 2013. She interviewed Lita Proctor, director of the Human Microbiome Project, a National Institute of Health (NIH) initiative to characterize the bugs that colonize human beings. People think of these bugs and bacteria as germs and pathogens, but they are really part of our bodies. Healthy adults carry about 5 pounds of bacteria in their digestive tracts (about the weight of the human brain). We need them to live and prosper but when things go wrong they can be implicated in disease. Recent studies have shown that certain microbes spew out a chemical linked to heart disease after breaking down components of meat and eggs. We don't appreciate the full ramifications of these bacterial buddies in human health so here are five facts I found fascinating:

  

FACT 1: They Move In at Birth

 

Your first wave of gut bacteria comes from the wild ride through the birth canal, according to Proctor. "It's during the event of birth that the initial and important inoculums of microbes happen," she said, adding that babies born by cesarean section might get a different dose of bacteria. "Nature meant for us to be born vaginally, and babies that don't get that exposure might not start out with the bacteria they're supposed to have." Breast milk is another important source of gut bacteria, according to Proctor. And it also contains nutrients that feed the bugs, called prebiotics. "Some breast milk compounds are actually meant to be consumed by the bugs. We can't digest them," Proctor said, adding that breast milk also contains crucial antibodies. "There's a purpose for breast milk."

 

FACt 2: They Fight Off Disease

 

Gut bacteria are our first defense against "actual germs," according to Proctor. "They hold down the fort," she said, describing how gut bacteria "outcompete" invading bugs that cause disease. "They themselves produce antimicrobials that can kill invading pathogens." Studies in mice suggest gut bacteria play an important role in immunity, with mice engineered to be free of all microbes developing abnormal immune systems or none at all. "Microbes help teach our bodies self from non-self," Proctor said, describing how a confused immune system might lead to allergies and other diseases. "Diabetes, rheumatoid arthritis, certain cancers, gut disease, there's work emerging that suggests an imbalance of microbes. We're not quite sure if it's cause and effect, but we know there's some type of contribution."

 

FACT 3: They Outnumber Us

 

The microbes in our bodies outnumber our own cells 10 to one [600 trillion microbes versus 60 trillion cells], according to Proctor. "The reason it's not apparent when you look in the mirror is they're much smaller than your own cells and the vast majority of them are living in your gut," she said. They outnumber us in genes, too. The Human Microbiome Project has identified about 8 million microbial genes, compared with the roughly 20,000 genes uncovered by the Human Genome Project. "Less than 10 percent of the DNA in each of us is from homo sapiens," said Hazen. "The vast majority is actually bacterial."

 

FACT 4: They Take a Cut of Our Food

 

After gobbling down the indigestible nutrients in our mothers' breast milk, gut bacteria continue to take a cut of the fruits, vegetables and grains we eat every day. The microscopic meals, called prebiotics, fuel the bacteria, which in turn keep our bodies in balance. It's "a symbiotic relationship," according to Hazen, who studies how the byproducts of microbial metabolism can influence our risk of disease. "The only thing we know is that long-term dietary patterns can make an impact on the gut microbiome." According to Hazen's research, "a longstanding diet low in animal products" appears to influence the microbiome for the better. But he says more work is needed to tease out the true relationship between the bugs we house and the food we eat.

 

FACT 5: They're Changeable

 

Unlike the 200,000 genes we inherit from our parents, our gut bacteria are changeable. "That's the beauty of it. We can alter them with diet and scientifically-based probiotics," Proctor said, explaining how probiotic supplements and foods, like yogurt, can introduce new bacteria into our guts, potentially easing a range of symptoms. And let's not forget about the fecal transplant - a procedure that helps restore the crucial gut bacteria balance with bugs from a healthy donor's poop. It's gaining popularity among patients with certain gut disorders and infections, and Proctor said it could hold promise for other diseases, too.

 

Clearly there is much to learn about how bacteria works in our bodies. The intricacy and details of human biology all point to the amazing, purposeful, design of life.