Pesticides may increase the need for selenium

The use of glyphosate-based herbicides to control weeds may increase the need for selenium, according to a new population study published in Ecotoxicology and Environmental Safety. Choosing organic produce may therefore be worthwhile if you want to avoid pesticide residues in food. It is also important to ensure adequate selenium intake.

In 2017, the International Agency for Research on Cancer (IARC) classified glyphosate as a “possible carcinogen” (Barnor et al., 2023). More recent population studies have also linked glyphosate exposure to a range of health risks, including insulin resistance, metabolic syndrome, obesity, cognitive decline, disrupted iron metabolism, and increased risk of premature death.
These health risks are partly due to glyphosate’s ability to integrate into proteins, taking the place of the amino acid glycine. Glyphosate can therefore disrupt glycine’s functions, including the formation of chromodulin, which affects insulin activity and the regulation of stable blood sugar levels.
Glyphosate may also interfere with the body’s transport and utilization of minerals - including selenium, iron, and manganese – leading to local imbalances.
In the new population study, researchers examined the relationship between glyphosate exposure, selenium intake, blood selenium levels, and risk of premature death. They emphasize that selenium is crucial for a number of antioxidants that protect cells against damage caused by free radicals and oxidative stress. In addition, selenium is a component of approximately 25–30 different selenoproteins and enzymes, which together support cellular energy metabolism, overall metabolism, immune function, circulation, cancer prevention, fertility, and other vital processes.
The researchers analyzed data from the large U.S. NHANES population study, which tracks participants’ diet, lifestyle, and health over time. The new study included 6,410 children and adults. Urinary glyphosate levels were measured in all participants. Dietary selenium intake was assessed via questionnaires, and full blood analyses were performed to measure blood selenium content. Confounding factors such as age, sex, ethnicity, smoking, alcohol consumption, and chronic diseases like diabetes were accounted for. Data on participant mortality were obtained from follow-up studies.
The study revealed that higher urinary glyphosate levels were significantly associated with increased mortality from cardiovascular disease and other illnesses. A negative correlation between urinary glyphosate and selenium levels was also observed. The researchers suggest that high dietary glyphosate exposure may lead to reduced selenium status, which can have serious health consequences. This indicates that glyphosate may increase the need for selenium. EFSA (the European Food Safety Authority) has set a safe upper daily limit for selenium at 300 micrograms.

How can glyphosate disrupt selenium utilization?

In the introduction to the study, the authors describe several ways glyphosate may interfere with selenium uptake and utilization:

• Glyphosate may disrupt plants’ uptake of selenium, resulting in lower selenium content.
• Glyphosate may interfere with enzyme activity in certain selenium-dependent lactic acid bacteria in the gut microbiota.
• Glyphosate may impair the body’s own use of selenium, including the formation of selenium-containing antioxidants (GPXs, glutathione peroxidases), which protect cells and tissues
• Glyphosate may cause selenium deficiency in the blood, which is associated with increased risk of cardiovascular disease, cancer, and other illnesses.

Glyphosate can enter cells and take the place of glycine. This reduces glycine availability, which is also important for the formation of selenium-containing GPX antioxidants. A deficiency of GPXs makes cells more vulnerable to oxidative stress - a state in which harmful free radicals exceed protective antioxidants. Oxidative stress also increases the risk of free radicals attacking essential LDL cholesterol, causing it to oxidize, become dysfunctional, and be consumed by white blood cells, which then deposit as foam cells in vessel walls. Free radicals thus contribute to atherosclerosis, regardless of whether cholesterol is high or low, with the final stages involving a calcium lattice around the foam cells in vessel walls.
Selenium-containing antioxidants (GPXs) also protect cell membranes, DNA, proteins, and other cellular components from damage caused by free radicals. When GPXs are deficient and oxidative stress is present, cells are more vulnerable, increasing the risk of cancer and many other diseases. It is therefore concerning that glyphosate can disrupt selenium uptake and utilization.

• Selenium is found in fish, organ meats, meat, eggs, and Brazil nuts.
• Selenium content in grains and other crops depends on soil composition.
• Most Americans consume more selenium through diet than Europeans, as U.S. soils are naturally richer in selenium.
• Selenium deficiency is common in Europe, where soils are selenium-poor.
• Use of glyphosate-based herbicides may increase the need for selenium.

References:

Pei-Lun Chu et al. Urinary glyphosate, selenlim status, and their impact on mortality: Evidence from NHANES 2013-2018. Ecotoxicology and Environmental Safety 2025

Osaka University. Selenoproteins: The fountain of youth? ScienceDaily. 2025