Interesting article on how our mysterious, bacteria ridden gut may be affecting our health. Poorly edited by mon self for brevity's sake. I recommend reading the full article, if you dont have any parties to go to. A Study in Balance: How Microbiomes Are Changing the Shape of Environmental Health http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3237378/ 'New findings about the ways in which human microbiomes transform arsenic and mercury—two of our most prevalent and well-defined external human health hazards—suggest the role of commensal bacteria may equal or exceed that of genetic polymorphisms that regulate metal transformations within the body, says Ellen Silbergeld, a professor of environmental health sciences at the Johns Hopkins University Bloomberg School of Public Health. To a toxicologist, a contaminant is only “in the body” once it has crossed from the external environment into circulating blood, or a cell, or an organ. But new findings suggest biologically relevant transformations may take place prior to absorption, when contaminants interact with the microbiome in the mouth, intestines, or other tissues. Because of the metabolic processes mediated by microbiomes, a great deal of what toxicologists attribute to human metabolism—such as methylation of arsenic—may actually take place at least in part before contaminants cross into the internal environment of our bodies. Scientists agree that re-examining environ-mental exposures through the lens of the microbiome is likely to yield more insights into bacterial impacts. For instance, the ability of intestinal bacteria to demethylate methyl-mercury19 is important because the process could result in unexpected exposure to toxic inorganic mercury. “It is possible that [many people] may be internally exposed to inorganic mercury much more than we have ever calculated because of demethylation of the mercury we take in through fish consumption,” Silbergeld says. The human intestinal microbiome appears to fall into one of three distinct enterotypes, or bacterial profiles. Analysis of 39 intestinal microbiome metagenomes of adults from four European countries, the United States, and Japan indicates individuals have one of these three enterotypes, which are characterized by higher proportions of Bacteroides, Prevotella, or Ruminococcus species.11 The enterotypes cross international and continental borders, as well as race, ethnicity, sex, and age. It is too soon to know how the three enterotypes differ in their ability to process environmental agents. In adulthood the composition of microbiomes is influenced not only by host genetics but also by the environment, diet, and other factors.4,5,6,7 If the composition of a microbiome changes, the range of services it provides its human host also may shift. New evidence indicates our microbiomes are, in fact, “chemical factories” that produce a complex set of molecules, including druglike compounds and peptides that act as neurotransmitters. One family of microbes may biotransform contaminants into a new form, whereas another group may transform that new form back into its previous form or into something completely new with completely different biological activity.' So who knows what our microbiome is doing to us? Mine are making me incredibly dumb, whilst still being quite adorable and humble. In some ways they seem to own us, as this science dude points out- “We may exist at the pleasure of the microbes.”'