Glyphosate, a herbicide widely used to control weeds, has been banned in dozens of countries globally and by multiple Australian local governments because of its toxicity to humans. Glyphosate and its side effects have become a major concern due to widespread use and its concentration in edible products. [1]

It does, however, continue to be used, despite its toxicity. So, what is the scientific evidence of its effects? How do we identify symptoms of exposure and how do we avoid exposure altogether?

Read on to find out more about this widely used herbicide.

What is glyphosate?

Glyphosate is a herbicide that was first sold to farmers in 1974 by Monsanto, the company that was acquired by Bayer. Since the late 1970s the use of glyphosate-based herbicides (GBHs) has increased approximately 100 times, although some estimates say it is likely to have increased by 300 times.

In Australia, there are over 500 products containing glyphosate registered for use by the Australian Pesticides and Veterinary Medicines Authority (APVMA). [2]

Many Australian farmers use glyphosate, which is sold as Roundup, with paraquat, a more toxic herbicide, to kill weeds prior to sowing their crops.

Glyphosate is a broad-spectrum herbicide, which means that it cannot be used to kill specific weeds or plants. Instead, it kills most broadleaf plants in the area it is used. It is absorbed into plants primarily through its leaves, and only tiny amounts of it are absorbed into the roots. Consequently, glyphosate is actually only effective at killing growing weeds and grass. It cannot stop seeds from germinating in the first place.

Once it is absorbed into the plant structure, glyphosate spreads all around the plant—to its roots and leaves—and prevents it from making proteins that are necessary for its growth. This is what ends up killing the plants. [3]

How does it work?

Glyphosate is a phosphonic acid derived from a reaction between the methyl group of methylphosphonic acid with the amino group of glycine. It works by inhibiting the action of a metabolic pathway called the shikimate pathway. This pathway plays a role in the synthesis of three amino acids named phenylalanine, tyrosine, and tryptophan. It is crucial for plants and some microorganisms but does not exist in humans.

It is argued that as this pathway is not present in people and animals, it is not harmful to us. However, our digestive system does contain microorganisms that make use of this pathway. It also influences other pathways which are based on humans and animals. The shikimate pathway is present in our gut bacteria and many other microbes that make up the 39 trillion microbial cells that make up the entire human microbiome, which play vital roles in our development, immune system, and overall health.

How are we exposed to glyphosate?

Glyphosate is widely used and so it can be found in our soil, waterways, food made with treated crops, and meat and dairy from livestock that were fed those crops such as fresh fruits, cereals, vegetables, and many other food products.

In terms of physically being in contact with the chemical, you can be exposed to glyphosate if you get it on your skin, in your eyes or breathe it in when you are using it. You might swallow some glyphosate if you eat or smoke after applying it without washing your hands first. You may also be exposed if you touch plants that are still wet with spray.

How can glyphosate affect the body?

Concerns about the safety of glyphosate have been broadly discussed and publicised in recent times. The carcinogenic potential of glyphosate-based herbicides has been extensively debated issue within many international agencies with contrasting opinions.

However, glyphosate has been reported to increase the risk of cancer, endocrine-disruption, celiac disease, autism, effect on erythrocytes and leaky-gut syndrome.

Glyphosate and cancer

The report of World Health Organization (WHO) in 2015 reclassified glyphosate as probably carcinogenic.

Several cancers including liver, kidney, pancreas, and breast cancers have been associated with glyphosate exposure. Research shows glyphosate can cause DNA damage and the types of mutations associated with these cancers.

In 2019, researchers at University of Washington concluded that using glyphosate increases the risk of non-Hodgkin lymphoma by 41 percent. In the study, published in Mutation Research, researchers wrote that an analysis of human epidemiological studies “suggests a compelling link between exposures to [glyphosate-based herbicides] and increased risk” for non-Hodgkin lymphoma. [4]

Glyphosate and gut bacteria

Although the direct toxicity of glyphosate has been considered when setting acceptable daily intake levels, its subtle effects on the gut microbiome have not, which means glyphosate’s influence on health may have been underestimated. [5]

Glyphosate performs as an inhibitor of 5-enolpyruvylshikimate-3-phospate synthase (EPSP synthase), not only in plants, but also in bacteria.

EPSP synthase inhibits intestinal microbiota, affecting mainly our beneficial bacteria while harmful bacteria, such as Clostridium spp. and Salmonella strains, are shown to be resistant to glyphosate.

Consequently, research suggests that glyphosate can cause dysbiosis, which is characterised by an imbalance between beneficial and pathogenic microorganisms. The overgrowth of bacteria such as clostridia generates high levels of noxious metabolites in the brain, which can contribute to the development of brain-related changes, [6] Dysfunction of the gut microbiome is associated with a host of diseases, including cardiovascular disease, some cancers, multiple sclerosis, diabetes, asthma, Crohn’s disease, Parkinson’s disease, and inflammatory bowel disease, as well as allergies, autism, depression, obesity, and other disorders or syndromes.

Glyphosate as an endocrine disruptor

Endocrine disruptors are chemical compounds that interfere with the normal functioning of the endocrine system and the reproductive and other biological processes regulated by it. They can cause developmental malformations, interference with reproduction, increased cancer risk and disturbances in the immune and nervous system function.

A study concluded that glyphosate satisfies at least eight key characteristics of an endocrine disruptor but stated that prospective cohort studies are still needed to elucidate the real effects in the human endocrine system. [7]

Glyphosate as an enzyme disruptor

Glyphosate inhibits key enzymes, including the cytochrome p450 enzyme.

These enzymes influence many cellular processes, including:

Detoxification of foreign substances
Cholesterol and vitamin D3 synthesis and degradation
Conversion of testosterone into estrogen [8]

Glyphosate and celiac disease

Researchers have suggested that glyphosate is partially responsible for the growing numbers of people with celiac disease and gluten intolerance worldwide. Celiac disease is associated with imbalances in gut bacteria that can be explained by the known effects of glyphosate on gut bacteria. Deficiencies in tryptophan, tyrosine, methionine and selenomethionine associated with celiac disease match glyphosate’s known depletion of these amino acids. [9]

Prevents absorption of minerals

Glyphosate prevents the absorption and utilization of minerals like copper, magnesium, cobalt, iron, zinc, calcium and magnesium.

Causes oxidative stress

Glyphosate depletes glutathione, our master antioxidant and a cornerstone of our biology, and it dramatically impacts our sulphur, methylation, and detoxification pathways that have many essential roles for our health. [10]

Studies have shown that glyphosate can induce oxidative stress as the body is unable to neutralise free radicals. Enough oxidative stress can damage cells, proteins, and DNA, contributing to the development of cardiovascular disease, autoimmune disease, and other chronic diseases. [11]

How can you avoid consuming food contaminated with glyphosate?

Eat organic

Buy organic produce wherever possible. Organic crops are not allowed to be treated with glyphosate.

A major study measured glyphosate and its main breakdown product, aminomethyl phosphonic acid (AMPA) in the urine of 16 people (seven adults and nine children) from four demographically and geographically diverse families. Researchers tested participants’ urine for glyphosate and AMPA over six days on a conventional diet, followed by six days on an all-organic diet, and found average reductions of more than 70 percent in both the adults and children.

These reductions were achieved after just three days on the organic diet, which is in line with animal studies showing most glyphosate leaves the body after five to seven days, though a smaller amount remains in and is eliminated more slowly from bone and bone marrow. [12]

There are some other steps you can take towards avoiding exposure to glyphosate. These include:

Take probiotics – glyphosate kills bacteria living in our gut so to protect against this damage and to help with glyphosate toxicity is to increase your consumption of dietary probiotics. Eat fermented foods such as sauerkraut, kimchi, kombucha, apple cider vinegar and yoghurts and take prescribed supplements in the correct dosage.

Eat more sulphur-rich foods – Glyphosate depletes sulphur in the body so try to eat more sulphur-rich foods such as eggs, organic cheese, onions and garlic. Inadequate sulphur can reduce your body’s ability to detoxify.

Take a manganese supplement – as glyphosate affects the body’s ability to absorb and utilise certain minerals, manganese can be found to be depleted. Manganese deficiency is linked to a wide range of health effects including mitochondrial function, gut health and cognitive decline. [13]

Future studies on the relationships between chronic glyphosate exposure and human health are needed but avoiding environmental toxins is a great step towards decreasing your risk of developing health issues from exposure.

Glyphosate and how it impacts our health