Gluten-Free Dieters May Have Unsafe Levels of Arsenic, Mercury


More Americans than ever are striking gluten from their diets, but those who choose to go gluten-free may have a heightened risk of consuming toxic metals.

A new study appearing in the journal Epidemiology found that individuals who adhered to a gluten-free diet had twice the amount of arsenic in their urine compared to people on a regular gluten diet. The study also found that gluten abstainers had 70 percent more mercury in their blood than non-dieters.

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The study results might spell trouble for the roughly 25 percent of Americans who have reportedly dodged gluten when making food consumption choices.

“These results indicate that there could be unintended consequences of eating a gluten-free diet,” said study author Maria Argos, Assistant Professor of Epidemiology at the University of Illinois at Chicago.

About 1 percent of the U.S. population has Celiac disease, an autoimmune disorder that’s tied to serious health problems when a person with the disease ingests gluten. A common protein, gluten is found naturally in grains like wheat, rye and barley, according to the Celiac Disease Foundation.

Related: New Study Busts the Myth That Healthy Foods Cost More

But many more Americans than just those with Celiac disease have embarked on a gluten-free diet, note the study authors. Many believe that cutting gluten from their diet can reduce inflammation throughout the body, although such ties have not been fully validated among the medical community.

High Metal Levels Found in Rice

Because gluten-free dieters must avoid wheat-derived products like bread and other grains, they often turn to rice flour as a substitute. The researchers believe a rice-heavy diet can lead to unsafe levels of arsenic and mercury because rice can “bioaccumulate” toxic metals from soil, water, fertilizers and other sources.

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To gain their findings, the research team from the University of Illinois at Chicago scoured data from the National Health and Nutrition Examination Survey. Of 7,471 study participants, the researchers identified 73 individuals who reported a gluten-free diet between 2009 and 2014.

The researchers found high levels of arsenic and mercury among the entire gluten-free subset. When consumed in unsafe levels, arsenic and mercury can lead to cardiac problems, cancer and cognitive impairments, among other health challenges.

Both arsenic and mercury can be found in unsafe levels in seafood, and public health groups urge individuals, especially pregnant women and others at risk, to limit their consumption of heavy-metal fish.

Related: New Guidelines Make It Easier for Pregnant Women to Eat Fish

While the new study throws caution on gluten-free diets that unintentionally increase levels of unsafe metals, the researchers believe further studies may be necessary to assess the dangers posed.

“Until we perform the studies to determine if there are corresponding health consequences that could be related to higher levels of exposure to arsenic and mercury by eating gluten-free, more research is needed before we can determine whether this diet poses a significant health risk,” said Argos.

Future studies can look across the Atlantic for guidance. “In Europe, there are regulations for food-based arsenic exposure, and perhaps that is something we here in the United States need to consider,” Argos said.

“We regulate levels of arsenic in water, but if rice flour consumption increases the risk for exposure to arsenic, it would make sense to regulate the metal in foods as well.”

Richard Scott

Richard Scott is a health care reporter focusing on health policy and public health. Richard keeps tabs on national health trends from his Philadelphia location and is an active member of the Association of Health Care Journalists.