We’re only beginning to learn the importance of healthy gut bacteria to our overall health—and the relationship between healthy soil and the human microbiome.

We know that the human microbiome, often referred to as our “second brain,” plays a key role in our health, from helping us digest the food we eat, to boosting our brain function, and regulating our immune systems. 

Similar to animals, plants and soil, our bodies contain trillions of microbes—microscopic living organisms, such as bacteria, fungi and protozoa. The microbes in each person’s body are unique, but not random. They colonize in the body, beginning from birth, depending on the microbes passed on by the mother. Over our lifetimes, they evolve according to our unique exposure to the outside world in order to protect us from disease such as cancer, diabetes and even autism.

What happens when our microbial community is disturbed? New research suggests that exposure to environmental toxins, such as pesticides, may alter the human microbiome, leaving us more vulnerable to sickness and disease.

A second new study suggests that the most widely used herbicide on the planet—Monsanto’s Roundup® weedkiller—could be causing more damage to our gut microbiome and overall health than we thought. Not only does the weedkiller contain glyphosate, but in its complete formulation, it also contains toxic levels of heavy metals, including arsenic.

Glyphosate and its unintended effects

A new study shows that Monsanto’s Roundup® weedkiller, which we already know damages healthy soil microbial activity, also damages the gut microbiome of rats.

The study, published by Prof Gilles-Eric Séralini at the University of Caen, France, raises new alarms about glyphosate, the most widely used herbicide in the world despite mountains of research pointing to the weedkiller’s damaging impacts on human and environmental health.

Glyphosate, the key active ingredient in Roundup®, is destructive to the environment. A recent article by GM Watch details the editor of No-Till Farmer, a magazine that advocates for the use GM crops and glyphosate herbicides in no-till systems, is changing his thinking.

John Dobberstein, No-Till Farmer’s senior editor, recently wrote that “there may be trouble on the horizon for glyphosate,” citing research showing that glyphosate lingers in the soil—and in high amounts—long after it has been applied.

Citing other researches, including Robert Kremer, a retired research microbiologist with the USDA-Agricultural Research Service and adjunct professor at the University of Missouri, Dobberstein wrote that glyphosate quietly lingers in soil years after it’s been sprayed, damaging non-target crops and suppressing beneficial mycorrhizal fungi, which help plants obtain nutrients from the soil while offering protection against disease.

The herbicide also harms beneficial soil organisms such as small insects and earthworms, while leaving behind chemical residues that wind up in our waterways, Dobberstein wrote, as reported by GM Watch.

Microbes prove their value in humans

While some microbes cause disease, the majority of these cells assist us with everyday processes, such as digesting food and keeping harmful bacteria at bay.

According to an article published this month by Mercola.com, 70 to 80 percent of your immune function resides within your gastrointestinal tract, or “gut.” Poor gut health is associated with autism, behavioral disorders, diabetes, gene expression and obesity.

If, as this recent article in the Atlantic claims, “The microbial community in the ground is as important as the one in our guts,” then the new Séralini study doesn’t bode well for us humans—especially if we keep dousing the world’s soils with glyphosate, and consuming glyphosate-contaminated foods.

Arsenic and old Monsanto

As if there aren’t enough reasons to be worried about glyphosate, one more reason emerged last week when scientists reported that glyphosate-based herbicides, including Roundup®, contain toxic levels of heavy metals, including arsenic.

Glyphosate, the active ingredient in Roundup® has been the subject of intense scrutiny and controversy. Documents recently made public as a result of multiple lawsuits filed against Monsanto by people who blame exposure to Roundup® for their non-Hodgkin lymphoma suggest Monsanto has known for decades about the health risks related to glyphosate.

Some countries have banned its use.

But as the authors of this latest study point out, glyphosate is not the only ingredient in herbicides like Roundup®—it’s one of multiple ingredients. Those other ingredients make glyphosate-based herbicides even more dangerous than we thought—and should lead to a global ban on all glyphosate-based herbicides.

According to Prof. Gilles-Eric Séralini, one of the authors of the study:

These results show that the declarations of glyphosate as the active principle for toxicity are scientifically wrong, and that the toxicity assessment is also erroneous: glyphosate is tested alone for long-term health effects at regulatory level but the formulants – which are composed of toxic petroleum residues and arsenic – are not tested over the long term. We call for the immediate transparent and public release of the formulations and above all of any health tests conducted on them. The acceptable levels of glyphosate residues in food and drinks should be divided immediately by a factor of at least 1,000 because of these hidden poisons. Glyphosate-based herbicides should be banned.

Will the U.S. Environmental Protection Agency (EPA) agree? And follow the lead of countries like France and Germany that have proposed countrywide bans on glyphosate?

We can only hope.

Julie Wilson is communications associate for the Organic Consumers Association (OCA). To keep up with these and other issues, sign up for OCA’s newsletter.