People who eat a gluten-free diet could be at increased risk of exposure to mercury and arsenic. That's the basis of a new report titled "The Unintended Consequences of a Gluten-Free Diet," published Feb. 3 in the journal Epidemiology, the UIC News Center reports. Gluten-free products very often call on rice flour, as a substitute for wheat flour; however, rice is known to bioaccumulate - that is, become concentrated in the body of a living thing - toxic material like lead and mercury found in water, soil and fertilizers.
This could be worrisome for the increasing numbers of Americans - one-quarter of Americans in 2015, up 67 percent from just two years earlier - who call themselves gluten-free.
A report by Maria Argos, an associate professor of epidemiology at the University of Illinois at Chicago School of Public health, and her colleagues looked at data from the National Examination Survey investigating a possible link between a gluten-free diet and the buildup of these toxic chemicals in urine and blood.
Of nearly 7,500 participants who took the study from 2009-14, Argos found 73 who reported eating a gluten-free diet, ranging in age from 6 to 80 years.
Those who ate a gluten-free diet had higher concentrations of both mercury in their blood (70 percent higher than normal) and arsenic in their urine (twice as much) as those not abstaining from gluten.
As the report's discussion reads, "With the increasing popularity of gluten-free diets, these findings may have important health implications since the health effects of low-level arsenic and mercury exposure from food sources are uncertain but may increase the risk for cancer and other chronic diseases."
However, there's much more work to be done before any serious dietary decisions need to be made - and there's not yet a guarantee these increased toxins came from rice flour.
As Argos and her colleagues concluded, "While our study is cross-sectional and relies on self-reported data regarding gluten-free diets, it does suggest that future studies are needed to more fully examine exposure to toxic metals from consuming gluten-free foods."
One possible solution, mentioned by Argos, looks to Europe, where levels of arsenic in food are strongly regulated. In the U.S., water is currently regulated for arsenic content - perhaps it's time to look at food, too.