Why is it that non-celiac people on a gluten-free diet claim they can eat wheat products if they are organically grown? Maybe it’s not what’s in the wheat, but what’s on it.
Organic crops are those grown with approved natural pest controls and non-chemical fertilizers. Fields must have foregone non-organic treatments for a minimum of 3 years to allow residual farming chemicals to dissipate. Moreover, no genetically modified plants nor hormones are used. It is a costly process.
Non-organic foods are made from crops grown with cheaper synthetic fertilizers and pesticides. Some pesticides kill bugs (insecticides), some combat fungal infections (fungicides), and others are herbicides which kill weeds.
Pesticides that are approved are initially considered safe, but over time, unintended human consequences may be recognized. Environmental repercussions are often overlooked or dismissed early on, taking longer to be recognized. Human impacts include general toxicity, carcinogenesis, gastrointestinal problems, and neurologic, immunologic, metabolic, endocrine, and developmental disruptions. Two herbicides (glyphosate and 2,4-D) and one insecticide (chlorpyrifos) have been linked to negative effects on the gastrointestinal (GI) microbiome. Of these, glyphosate has been most studied.
Glyphosate (gly-FOS-ate) is an indiscriminate herbicide, killing both broadleaf and grass-like plants within 3 weeks of leaf contact. Initially approved to kill weeds in 1974, glyphosate uses have expanded, sales have grown exponentially, and it is now the best-selling herbicide worldwide. Glyphosate-based weedkillers often contain other (supposedly safe) ingredients to improve solubility, sticking, and absorption. These products are found under many brand names, the most famous being RoundUp®.
Glyphosate manufacturers originally claimed that it was safe for humans since it kills weeds by targeting an enzyme in the shikimate metabolic pathway found in plants, but not animals. However, this enzyme pathway is present in many bacteria, including those residing in the guts of humans as well as pets, livestock, and bees. While it would take a very large dose of glyphosate to kill a human, it is unknown what amount is toxic to our beneficial gut bacteria.
Glyphosate was also investigated for links with non-Hodgkin lymphoma, and with concerns about its carcinogenic and gut microbiome effects, several European countries have increased regulations on its usage or banned it outright. The EPA seemingly does not share those concerns and higher residual levels are tolerated in the US compared to those in the EU.
Originally, farmers used glyphosate to kill weeds prior to planting. Then, genetic modifications of corn, soy, rapeseed (canola), and sugar beets (GMOs) were created to render immunity to this herbicide. When glyphosate is sprayed on these GMO crops, only the surrounding weeds wither and die so, it can be used as needed during the growing season.
Then, in the 1990s, glyphosate was applied as a desiccant and sprayed on mature crops (e.g., wheat, oats, barley, rye, buckwheat, millet, beans, lentils, sugar cane, flax, sunflowers, and other oilseeds). This causes weed death and hastens the crop plant demise, often for a predictable harvest time. Residual glyphosate might be present at the time of harvest although some is removed with the outer husks in the case of grains. Some farmers spray glyphosate between rows of fruit trees and vines to reduce weeds in orchards and vineyards, some of which may be absorbed through the roots into the plant and its fruit.
Besides crops, pesticide residues also accumulate in livestock and fish that have consumed tainted crops and water adulterated by agricultural run-off. While measurements of residues in foods might be deemed within a safe range, these levels are not shared with the public who are likely consuming produce or animal products with exposures from multiple sources. Glyphosate residue measurements have important implications as exposed crops are used in baked goods, cereals, snacks, cooking oils, vegetarian protein sources, beer, and wine.
Depending on the total residues consumed, an individual could develop dysbiosis (a predominance of unhealthy gut bacteria) if populations of healthy bacteria are harmed by the glyphosate. The resulting bacterial imbalance allows “undesirable” bacteria to gain the upper hand, leading to negative effects including GI symptoms (e.g., abdominal discomfort, bloating, cramping, and diarrhea), decreased synthesis of short chain fatty acids (a desirable product), inflammation, immune dysfunction, and perhaps, behavioral effects.
Given our current knowledge, we need further evaluation of glyphosate safety (and its adjuvant ingredients) and a revisitation of acceptable residue levels on foods for humans, pets, and livestock by the EPA.
Glyphosate continues to be the most popular herbicide worldwide by farmers, but restrictions imposed by some European countries have limited farm applications and banned homeowner use. For instance, Italy banned pre-harvest use of glyphosate as a desiccant since 2016, although it still allows its use for weed killing prior to planting.
You can reduce your own exposure to pesticide residues by purchasing organic foods, grains, and produce. Organic food is usually expensive, so focus first on those products you’ve noticed bother your gut like bread, pasta, or oats. Some companies like Bob’s Red Mill have responded to customer demands and buy from growers that don’t use glyphosate as a desiccant for some of its grains, like oats. Regarding fruits and vegetables, eat fewer of the “dirty dozen” and more of the “clean fifteen” as referenced by the Environmental Working Group. Local produce grown with integrated pest management techniques may be safer, but you might ask about glyphosate use in the fields.
To reduce exposures at home, avoid using herbicides containing glyphosate. Don’t let your pet roll around in areas where it may have been used like roadsides (dead and dying plants are a clue); licking off glyphosate residues might result in gastrointestinal issues. To learn more about food and pesticides, check out these sites for the Environmental Working Group, the Center for Science in the Public Interest, and the Center for Food Safety.
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