Gluten-free diets linked to heavy-metal bioaccumulation

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Takeaway

  • People following a gluten-free diet (GFD) bioaccumulate significantly higher levels of lead, arsenic, mercury, and cadmium than people not on a GFD.
  • Editorial applauds the study, advises against routine heavy-metal testing, and suggests those who do not require a GFD “carefully should weigh the negative consequences...against any perceived benefits.”

Why this matters

  • GFDs are growing in popularity even among people not diagnosed with a gluten-related disease.
  • Such diets can lack fiber and micronutrients and contain excess salt, sugar, and fat.
  • Rice and fish, often consumed in larger amounts in GFDs, are contaminated with heavy metals.

Key results

  • 115 participants followed GFD (11 with celiac disease [CD]).
  • Univariate analysis (GFD vs not):
    • Mercury: 1.37 vs 0.93 mcg/L (P=.008);
    • Lead: 1.42 vs 1.13 mcg/L (P=.007); 
    • Cadmium: 0.42 vs 0.34 mcg/L (P=.03); and
    • Arsenic: 15.15 vs 8.38 mcg/L (P=.002).
  • Multivariate analyses remained significant.

Study design

  • Population-based, cross-sectional study, National Health and Nutrition Examination Survey (NHANES) data, 2009-2012 (n=11,354 adults).
  • Blood samples tested for serologic CD; participants asked about CD, GFD.
  • Researchers adjusted for confounders, including fish consumption (for mercury).
  • Endpoints: lead, mercury, cadmium levels in blood (n=11,354); urinary arsenic (subset, n=3933).
  • Funding: CDC.

Limitations

  • Few people were following GFD.
  • Long-term clinical significance unknown.