Following a gluten-free diet may be the “it” thing to do these days, but unless you have celiac disease, you may needlessly be exposing yourself to toxic metals that can do serious damage.

Less than one percent of Americans have been diagnosed with celiac disease — an out-of-control immune response to gluten, a protein found in wheat, rye and barley. However, one-quarter of Americans reported eating gluten-free in 2015.

Some say they prefer eating gluten-free because it reduces inflammation. However, their beliefs are based on a claim that has not been scientifically proven. And by doing so, University of Illinois at Chicago researchers say they are putting themselves at risk for increased exposure to arsenic and mercury — toxic metals that can lead to cardiovascular disease, cancer and neurological effects.

Gluten-free products often contain rice flour, which is known to bioaccumulate certain toxic metals, including arsenic and mercury from fertilizers, soil, or water. However, little is known about the health effects of diets high in rice content.

To learn more, the researchers looked at data from the National Health and Nutrition Examination Survey searching for a link between gluten-free diet and biomarkers of toxic metals in blood and urine. They pinpointed 73 participants ranging in age from 6 to 80 years old who reported eating a gluten-free diet among the 7,471 who completed the survey.

All had higher concentrations of arsenic in their urine, and mercury in their blood, than those who did not, according to Maria Argos, assistant professor of epidemiology in the UIC School of Public Health, and her colleagues. What’s more arsenic levels were almost twice as high for people eating a gluten-free diet, and mercury levels were 70 percent higher.

“These results indicate that there could be unintended consequences of eating a gluten-free diet,” Argos said. “But 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.”

“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.”

Results are published in the journal Epidemiology.

Catherine Bulka of UIC; Matthew Davis of the University of Michigan; Margaret Karagas of Dartmouth University; and Habibul Ahsan of the University of Chicago are co-authors on the paper.
This research was supported by National Institutes of Health grants R01 ES024423, R21 ES024834, R01 CA107431, P42 ES010349 and T32 HL125294.