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Switching from a diet of conventionally grown foods to an all-organic diet dramatically reduces the levels of glyphosate in your body in just six days, according to a new study from scientists with Friends of the Earth, an environmental advocacy group. The study was published in the journal Environmental Research. 

Glyphosate, the active ingredient in the herbicide Roundup, is the most widely used pesticide in the U.S., according to a 2016 study. It has a variety of uses, including killing weeds on fields before planting, and it’s often applied to crops, such as corn and soybeans, that are genetically modified to be resistant to it—the engineered plants survive, but glyphosate kills the weeds. It’s also used in consumer gardening products. 

In an earlier phase of the study, the researchers found that eating organic also reduced levels of a variety of other pesticides within a week. 

According to study author and Friends of the Earth senior scientist Kendra Klein, Ph.D., this research demonstrates “how rapidly we can get these pesticides out of our bodies.”

The Health Effects of Glyphosate

Glyphosate was first introduced in 1974, and as its use has grown, so has humans’ exposure to it. According to one 2017 study, glyphosate could be detected in more than 70 percent of people between 2014 and 2016. 

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As with many pesticides, the health effects of low-dose, chronic exposure to glyphosate through food aren’t fully understood. But existing research has found that glyphosate is linked with a risk of non-Hodgkin's lymphoma, liver and kidney problems, and disruptions in the body’s hormone systems. 

The amounts of glyphosate that are currently legally allowed on food aren't harmful, federal regulators with the Environmental Protection Agency say. “Last year, both EPA and Health Canada reaffirmed that glyphosate poses no risk to public health and is not likely to be carcinogenic," says Chris Novak, CEO of CropLife America, a pesticide-industry trade group. "EPA’s most recent assessment is fully consistent with the science-based conclusions reached by leading health regulators worldwide for more than four decades, that glyphosate-based herbicides can be used safely as labeled.”

Still, the World Health Organization's International Agency for Research on Cancer does classify glyphosate as a probable cancer-causing agent. And Bruce Lanphear, M.D., M.P.H., a public health physician and professor at Simon Fraser University in British Columbia, who wasn’t involved in the new study, suspects that it's possible that tolerance levels set by the EPA might be too high.

Other substances, such as lead, the insecticide DDT, the industrial chemicals known as PCBs, and more, were once assumed to be safe in small doses, he notes. “Years later we found out that, no, they were not safe,” Lanphear says—they actually had significant health impacts even at very low levels.

What the Study Found

For the study, researchers recruited a racially diverse group of four families: one each from Oakland, Minneapolis, Baltimore, and Atlanta, and each with two or three children between 3 and 18 years old. 

For the first five days of the study, the families followed their typical diets, which was made up of conventionally grown foods. 

In the second half of the study, which lasted six days, the researchers provided all organic food for the families to eat instead, replicating their food choices based on food diaries and grocery shopping lists the participants had provided. “Everything they would typically eat, they were just eating organic,” Klein says. That included their typical breakfasts, lunches, dinners, and snacks, and also beverages, such as organic beer and wine, and even organic sports drinks. Klein notes that they checked to make sure that beyond conventionally raised versus organic foods, the participants’ diets didn’t change—they weren’t eating more fresh produce or less meat, for example.

On each of the 11 days and the morning of day 12 the study participants provided urine samples to the researchers, who tested the samples for the presence of glyphosate and a variety of other pesticides. 

All the participants had markers for glyphosate in their systems at the start of the study, notes Klein, an important finding because little data exists on how widespread glyphosate exposure is. 

At the end of the study, glyphosate levels were about 70 percent lower on average. That's similar to findings from the earlier phase of the study, in which levels fell by about 60 to 95 percent for some of the other pesticides.

The study had some limitations. The number of participants was small—four families and a total of 16 people. With urine collected every day, however, researchers had 158 samples to evaluate. And this study is still the largest of its kind, notes Klein, in part due to the labor-intensive nature of providing an entire week’s worth of organic food to the participants. 

And diet isn't the only way we’re exposed to pesticides. This study couldn’t account for the pesticides people encountered in their environment, whether work, home, school, or out in public. 

Still, Lanphear says, the results of this study demonstrate that by switching to organic foods, “More likely than not you’re going to reduce your exposure to a variety of pesticides, including glyphosate.”

What the Study Findings Mean for You

According to Klein, while following an all-organic diet would reduce your pesticide intake the most, even replacing some conventionally produced foods with organic will have benefits. For example, in one study published last year in the journal Environment International, pregnant women who ate mostly, though not exclusively, organic produce for 6 months had lower levels of markers for pyrethroids, a common class of pesticides, in their urine compared with pregnant women who ate conventionally grown produce. 

That’s good news, since organic food can be more expensive, and in some places, harder to find than conventionally produced foods. (Learn more about how to save money when shopping for organic groceries.)

And although Consumer Reports’ food experts recommend consumers choose organic foods when they can, “we realize that organic isn't an option for everyone,” says Charlotte Vallaeys, CR’s senior policy analyst for food and nutrition.

But studies like this one from Friends of the Earth confirm how important it is for the federal government to increase support for organic farmers, “to make organic food the norm rather than a pricier alternative only available to those who can afford it.”