Research conducted at Montana State University shows that microbes in the human gut play an important role in protecting against arsenic toxicity, a problem that affects an estimated 200 million people who are exposed to arsenic through contaminated drinking water.

For the past five years, MSU doctoral candidate Michael Coryell has worked with his adviser, Seth Walk, and committee member, Timothy McDermott, to research how the human gut microbiome affects arsenic after it has been ingested. Now, Coryell is the lead author of a paper published Dec. 21 in the journal Nature Communications that details his findings of how the gut microbiome is essential for full protection against acute arsenic toxicity.

With arsenic topping the federal Agency for Toxic Substances and Disease Registry's list of the most toxic chemicals for the past 20 years, the research is particularly important because even chronic low levels can lead to cancer or cardiovascular disease later in life.

Coryell, a doctoral candidate in microbiology and immunology and fellow in the Molecular Biosciences Program in MSU's College of Agriculture and the College of Letters and Science. This work will contribute to the development of probiotic and microbiome-focused therapies that can mitigate the risk for arsenic toxicity.

Past studies have shown that microbes in the environment can biochemically transform naturally occurring arsenic in soil or rocks either into less toxic or more toxic forms a topic McDermott researches in MSU's Department of Land Resources and Environmental Sciences in the College of Agriculture.

What researchers don't know as much about is what microbes in the human gut do with arsenic before it is absorbed into the body. There are many factors that influence disease a person's environment, diet, genetics but we can only evaluate some of those things in human studies by observing different genotypes of people who have different diets or drink water from different sources.

Those results suggest that the microbiome of some people may be more protective than others and may answer the question of why some people who drink from a shared water source tainted with arsenic develop disease later in life while others don't.