“These results indicate that there could be unintended consequences of eating a gluten-free diet,” said study author Maria Argos of the University of Illinois at Chicago (UIC).
Gluten-free products often contain rice flour as a substitute for wheat, rye and barley. And rice is known to accumulate arsenic and mercury from fertilizers, soil and water, said Argos, an assistant professor of epidemiology in the School of Public Health.
For the study, the researchers analyzed U.S. National Health and Nutrition Examination Survey data from thousands of Americans, aged 6 to 80. The investigators identified 73 people who said they ate a gluten-free diet.
Compared to other survey participants, those who ate gluten-free diets had nearly twice the levels of arsenic in their urine, and 70 percent higher levels of mercury in their blood, according to the study.
However, “more research is needed before we can determine whether this diet poses a significant health risk,” Argos said in a university news release.
Gluten-free diets are recommended for people with celiac disease — an out-of-control immune response to gluten, a protein in wheat, rye and barley.
Just 1 percent of Americans have been diagnosed with the disorder, but nearly one-quarter of Americans reported eating a gluten-free diet in 2015, the researchers noted.
Many consumers believe gluten-free eating reduces harmful inflammation, but there is no scientific evidence supporting that, the study authors said.
While the study raises questions about going gluten-free, it doesn’t show a direct cause-and-effect relationship between that eating style and higher toxin levels.
Still, “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.”
The study results were published online recently in the journal Epidemiology