Researchers have found that individuals who adhere to a gluten-free diet had 70% higher levels of mercury in their blood and nearly double the arsenic levels in urine than those who were not on the diet. These findings were reached using the National Health and Nutrition Examination Survey. The authors hypothesize that the higher levels could be due to gluten-free products using rice flour as a substitute for wheat. With an estimated 25% of Americans consuming gluten-free food in 2015 – despite only 1% of the population having a diagnosis of celiac disease – the authors of the study suggest that further research is needed to determine whether the gluten-free diet poses a health risk.