The Human Gut Does More Thinking Than The Brain

Microbes have become the new frontier of diagnostic research

They live in us and on us. The human metagenome, the DNA sequencing hitherto unexplored bacterial colonies, is being mapped much like the New World of 500 years ago. The National Institute of Health committed $140,000,000 to the Human Microbiome Project in 2007 to examine the trillions of creepy crawlers insinuating themselves in our lovely bodies. Not wanting to be left behind, the European Commission established in 2008 the C22-million ($29,000,000) Metagenomics of the Human Intestinal Tract project (MetaHIT), which focuses on gut bacteria. Results from these major global projects already show us how microbes influence disease expression and offer new ways of diagnosing and treating a wide range of maladies.

Human Just Bacteria

Within the body of a healthy adult, microbial cells outnumber human cells 10 to 1. “When I get up from my chair, 10 times more bacterial cells get up than human ones,” Dr. Bruce Birren , one of the US microbiome researchers, told media. Other experts such as author and physician Michael Loes, MD, say that the human gut with its trillions of bacterial cells does more thinking for us than our brain. The microbes in the body get energy from food, absorb vitamins and produce antioxidants, anti-inflammatory and detoxifying metabolic enzymes and novel compounds. Most of our immune system resides in the gut where bacteria are active. But scientists are discovering more variations in the metagenome looking at bacteria than genes alone and larger differences offer a new way of analyzing disease population variants with states of salubrity. We are learning how bacterial populations turn on and off disease processes.

Microbial Profiling

The metagenome has more variation than the genome. “There’s a 0.1% difference in our genomes but there may be a 50% difference in our metagenome,” Dusko Ehrlich, project coordinator for MetaHIT, told the media. “If the variability is higher, you’re more likely to find a relevant signal.”

Take inflammatory bowel disease or IBD, which includes two different pathologies, ulcerative colitis (UC) and Crohn’s disease (CD). The MetaHIT project compared patients in remission with a similar number of healthy individuals generally from the same family (30 for each disease). First results indicate that some bacterial species differ in the two groups. If fully confirmed, this may well lead to a breakthrough in understanding of this disease.

Obesity is associated with a number of co-morbidities such as diabetes, hypertension and cardiovascular diseases. They compared 60 individuals with 60 lean individuals. Once again the first bio-informatics analyses point to the differences in bacterial species between obese and lean individuals that could lead to a breakthrough in what to do about the cause of so much morbidity and mortality.

Systems biologist Jen Nielsen, Chalmers University of Technology in Gothernburg, Sweden, says the gut’s microbial genes may be a better predictor of type 2 diabetes than established risk factors such as waist-hip ratio or body mass index.

“These are early days but I think there is great potential in what we see now,” says Dr. Ehrlich. Although we have known about some popularized broad strains of bacteria found in the human gut and elsewhere in the body, most microbes populating human bodies have not been identified. Metagenomics is the new advance in DNA sequencing technology that allows overview examination of microbial colonies even when the organisms cannot be cultivated, using genetic materials taken from the natural environment.

Human Protectors

One pioneering area of study for these microbial communities is how they protect their human hosts, says Gregor Reid of the Lawson Health Research Institute, London, Ontario. Bacterial organisms are found in foods such as kimchi and tofu as well as yogurt and in dietary supplements. It is thought they help to remove lead, cadmium, arsenic, chromium and mercury. The team found that up to 60% of heavy metals human beings eat do not reach the bloodstream because they are broken down and captured by bacteria that transport them out in the feces. Study coauthor Jeremy Burton says that lactobacillus species found in the mouth and gut bind and remove heavy metals. “If the metal is trapped in or on a bacterial cell, it can pass harmlessly from the body via feces,” he told the media.

Lactobacillus and other strains of bacterial organisms detoxify the body from heavy metals and carbon molecules (bisphenol A) that impact neurobiological health.