Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. 
Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. What was studied?
The focus keyphrase “heavy metal bioaccumulation in gluten-free diet” is central to this study, which investigates whether individuals adhering to a gluten-free diet (GFD) in the United States exhibit higher levels of heavy metal bioaccumulation compared to those consuming a regular diet. The research specifically examines the concentrations of four toxic heavy metals, arsenic, mercury, lead, and cadmium, using data from the National Health and Nutrition Examination Survey (NHANES) collected between 2009 and 2012. The study is grounded in concerns that gluten-free diets often rely heavily on foods such as rice and seafood, which are recognized sources of these metals. By analyzing blood and urine samples, the researchers assessed whether following a GFD, regardless of a diagnosis of celiac disease, is associated with increased bioaccumulation of these metals. The study’s findings directly inform heavy metal certification programs by quantifying the risk posed by popular gluten-free staples.
Who was studied?
Participants were drawn from the US NHANES cohort, a nationally representative sample of the non-institutionalized civilian population. The study included 11,354 adults aged 18 years or older, with detailed dietary and health data available. Of these, 115 individuals reported following a GFD, while 11,239 did not. The subset for urinary arsenic analyses included 3,933 adults, with 32 participants on a GFD. Both celiac and non-celiac individuals were included, but most participants on a GFD (90.2%) did not have a celiac disease diagnosis. Demographic variables such as age, gender, race, and smoking status were adjusted for in the analyses. This broad, population-based approach allows findings to be generalized to the wider US adult population, making them highly relevant for regulatory and certification purposes.
Most important findings
| Critical Points | Details |
|---|---|
| Elevated Metal Levels in GFD | Individuals on a GFD had significantly higher blood mercury (1.37 mcg/L vs 0.93 mcg/L; P=.008), lead (1.42 mcg/L vs 1.13 mcg/L; P=.007), and cadmium (0.42 mcg/L vs 0.34 mcg/L; P=.03). Urinary arsenic was also higher (15.15 mcg/L vs 8.38 mcg/L; P=.002). |
| Non-Celiac GFD Adherents | People without celiac disease but on a GFD showed increased blood mercury (1.40 mcg/L vs 0.93 mcg/L; P=.02), lead (1.44 mcg/L vs 1.13 mcg/L; P=.01), and arsenic (14.69 mcg/L vs 8.32 mcg/L; P=.01) compared to non-GFD, non-celiac peers. Cadmium was higher, but the difference was not statistically significant (P=.06). |
| Seafood and Rice Consumption | Increased mercury was partially explained by higher reported fish and shellfish consumption among GFD followers; however, even after controlling for this, mercury levels remained higher. Elevated urinary arsenic likely reflects rice consumption, a gluten-free staple known for arsenic content. |
| Levels Below Toxic Thresholds | Most observed heavy metal concentrations in GFD adherents were below established toxicity thresholds, except for arsenic, where a higher proportion of GFD followers exceeded the OSHA threshold for inorganic arsenic exposure (3.8% vs 1.4%), though not statistically significant. |
| Demographic Factors | Differences in heavy metal levels persisted after adjusting for age, sex, race, and smoking. Notably, women on a GFD had significantly higher blood lead than women not on a GFD. Nonsmokers and ex-smokers on a GFD had higher blood cadmium than their non-GFD counterparts. |
Key implications
The elevated levels of heavy metals among people following a gluten-free diet, even when below most toxicity thresholds, underscore the necessity for rigorous heavy metal testing and certification of gluten-free foods, especially rice-based and seafood-containing products. Regulatory programs should target monitoring and mitigation to protect at-risk consumers.
Citation
Raehsler SL, Choung RS, Marietta EV, Murray JA. Accumulation of Heavy Metals in People on a Gluten-Free Diet. Clinical Gastroenterology and Hepatology. Accepted January 30, 2017. doi:10.1016/j.cgh.2017.01.034
Heavy metals are high-density elements that accumulate in the body and environment, disrupting biological processes. Lead, cadmium, arsenic, mercury, nickel, tin, aluminum, and chromium are of greatest concern due to persistence, bioaccumulation, and health risks, making them central to the HMTC program’s safety standards.
Arsenic is a naturally occurring metalloid that ranks first on the ATSDR toxic substances list. Inorganic arsenic contaminates water, rice and consumer products, and exposure is linked to cardiovascular disease, cognitive deficits, low birth weight and cancer. HMTC’s stringent certification applies ALARA principles to protect vulnerable populations.
Mercury (Hg) is a neurotoxic heavy metal found in various consumer products and environmental sources, making it a major public health concern. Its regulation is critical to protect vulnerable populations from long-term health effects, such as neurological impairment and cardiovascular disease. The HMTC program ensures that products meet the highest standards for mercury safety.
Lead is a neurotoxic heavy metal with no safe exposure level. It contaminates food, consumer goods and drinking water, causing cognitive deficits, birth defects and cardiovascular disease. HMTC’s rigorous lead testing applies ALARA principles to protect infants and consumers and to prepare brands for tightening regulations.
Cadmium is a persistent heavy metal that accumulates in kidneys and bones. Dietary sources include cereals, cocoa, shellfish and vegetables, while smokers and industrial workers receive higher exposures. Studies link cadmium to kidney dysfunction, bone fractures and cancer.
