Glyphosate and Gut Health: Is Oatmeal Dangerous?


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There is nothing quite like waking up in the morning to a tasty bowl of oats. A swirl of maple syrup, a spoonful of brown sugar, or a dash of cinnamon creates a concoction that feels like eating a warm cookie for breakfast. This not-so-guilty pleasure can be a healthy, satisfying meal. Oats are some of the healthiest grains in existence, providing antioxidants and fiber, not to mention vitamins and minerals. So why are concerns buzzing around the question: are oats bad for you?

Oats have come under controversy in recent years due to a pesticide, the weed killer known as Round Up, which according to research conducted by the Environmental Working Group (EWG) can be found in high levels in many popular oat-based food products. While oats are a primary crop that glyphosate is used on as a pre-harvesting drying agent, the pesticide is found in more than just oatmeal. According to EWG, glyphosate has also been found in additional products containing a variety of crops such as wheat, soybeans, corn, and chickpeas.

While conflicting assessments surround its safety for humans and animals, a major ingredient in the weed killer, glyphosate, is a substance classified by the World Health Organization’s International Agency for Research on Cancer in March 2015 as “probably carcinogenic to humans.” The state of California also added glyphosate to the right-to-know law, Prop 65’s, list of chemicals known to cause cancer, effective July 2017. As the companies and organizations behind Round Up have vehemently argued its safety for humans, lawsuit settlements and independent research have raised further concerns.

As much of the controversy surrounding glyphosate in food has focused on its probable carcinogenic properties, research is beginning to consider its potential negative effect on the gut microbiome as well. Based on laboratory tests in the pre gut microbiome era, supporters of the weed killer have asserted its safety because the product attacks an enzyme that is not found in humans or animals. Glyphosate is a small molecule that acts as an herbicide primarily by inhibiting the enzyme EPSPS (5-enolpyruvylshikimate-3-phosphate synthase), a key component of the shikimate pathway, a metabolic pathway found only in plants and microorganisms. Its inhibition blocks biosynthesis of aromatic amino acid in plants, resulting in their death.

The numerous assurances by Monsanto, the company that came up with the compound, and by other glyphosate proponents, are based on laboratory and test tube evaluations that do not take the gut microbiome into consideration. However, more recent research suggests that the pesticide can harm bees due to the reduction of beneficial gut bacteria that can leave them vulnerable to infection by pathogens. One study explains that most of the gut bacteria of bees contain the enzyme targeted by glyphosate.

Research from Finland in 2020 began to assess whether this finding about bees is relevant to humans. According to the study’s results, an estimated “54% of species in the core of the human gut microbiome contain the EPSPS enzyme and are therefore sensitive to glyphosate, which represents approximately a 20% of the total number of bacterial species in the gut.” While the study’s authors make clear that further research is needed to better understand the extent of these risks, their findings suggest that the use of glyphosate for agriculture could potentially pose a threat to the best health of the human gut microbiome.

As research on the effects of pesticides continues, countries around the world have moved towards banning glyphosate, including Luxembourg, Sri Lanka, Vietnam, and Thailand. Many additional countries such as Austria, Belgium, Netherlands, and France have moved towards full or partial restrictions as well. Germany is in the process of phasing out glyphosate from 2024 on. For oat lovers in countries such as the United States which are not currently approaching a federal ban of glyphosate, this research and the decisions of countries throughout the world, can serve as a warning about the likely dangers of this pesticide for human and animal health.

As the safety of important food sources is becoming increasingly under debate due to potentially risky agricultural practices, an American study from 2020 sheds light on a key way to limit exposure. This study examined changes in levels of glyphosate and its main metabolite, amino-methyl phosphonic acid (AMPA), in urine with an organic diet intervention. According to the results, “An organic diet was associated with significantly reduced urinary levels of glyphosate and AMPA,” returning to baseline in a matter of three days.

As the body of literature supporting the health benefits of eating organic is growing, it is up to consumers to decide for themselves what goes into their bodies and the bodies of their children. To understand what might be lurking in food products, EWG has made research publicly accessible by listing results of their tests of glyphosate in food and providing a food scores database for consumers to assess their products. It is up to each person to make thoughtful and informed decisions to protect their health to the best of their ability. As consumers exercise their purchasing power, one day maybe that delightful bowl of oatmeal might not be so controversial anymore.

Jamisen Cook is a writer with a specific interest in health. She holds a degree in Communications and a minor in English from the University of California Los Angeles and is in the process of completing her master’s of Science Writing at Johns Hopkins University.