Data collected from a survey found those following a gluten-free diet had urine arsenic levels almost twice as high as those following a conventional diet.
Mercury levels in the blood were found to be 70% higher in gluten-free individuals, according to the research team
The findings also speculate that rice may be the main contributing factor in the observations garnered from this study.
Commercial gluten-free products use rice flour as the primary substitute for wheat which, along with rye and barley, tend to aggravate an inflammatory gut reaction that characterises Coeliac disease.
“These results indicate there could be unintended consequences of eating a gluten-free diet,” said Dr Maria Argos, assistant professor of epidemiology at the University Of Illinois Chicago School of Public Health
“More research is needed before we can determine whether this diet poses a significant health risk.”
Further research needed
While the study is cross-sectional and relies on self-reported data, the results do suggest further studies are required to fully examine this toxic metal exposure as a result of following this diet.
Previous studies looking into low-level arsenic and mercury exposure from food sources have proved inconclusive but a link to neurological and other chronic conditions remain present.
In July 2014, UN food standards body the Codex Alimentarius Commission adopted new standards to protect consumer health worldwide.
This included setting out a maximum acceptable level of arsenic in rice of 0.2 milligrams per kilogram (mg/kg).
This was closely followed up in June 2015, where the European Commission proposed an arsenic level contained in non-parboiled milled rice (polished or white rice) to be no more than 0.2 mg/kg.
This proposal was made mandatory in all EU member states from the 1 January 2016 onwards.
Dr Argos and her colleagues looked at data from the National Health and Nutrition Examination Survey.
A total of 73 subjects were identified as consuming a gluten-free diet among the 7,471 individuals who completed the survey.
The questionnaires were distributed and completed between 2009 and 2014 and subjects ranged in age from 6 to 80 years old.
Along with arsenic and mercury, higher concentrations of dimethylarsonic acid and urinary cadmium were found among those on a gluten-free diet.
‘Health effects from exposure unknown’
“To our knowledge, this is the first analysis to suggest that Americans on gluten-free diets may be exposed to higher levels of arsenic and mercury,” the study said
“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.”
According to the Food and Agriculture Organisation (FAO), arsenic is naturally present at high levels in the groundwater and soil in some countries.
The food chain can become contaminated when the toxic elements enter the water and soil that are utilised by the crops.
Rice is particularly vulnerable as it can absorb more arsenic than other crops. Rice is also a staple food for millions of people significantly increasingly arsenic exposure in a population.
Source: Epidemiology
Published online ahead of print: DOI: 10.1097/EDE.0000000000000640
“The Unintended Consequences of a Gluten-Free Diet.”
Authors: Maria Argos et al