Jairoun et al. 2020 — Heavy metals in UAE dietary supplements

Summary

This is a large primary occurrence-and-exposure survey of toxic metals in dietary supplements, a product category the HMTc program covers. The authors measured cadmium, lead, and arsenic by ICP-MS in 277 supplement products sampled from the United Arab Emirates market and combined each product’s metal concentration with its labelled daily dose to estimate daily metal intake against acceptable-daily-intake (ADI) reference values. The headline finding is reassuring on average but informative on structure: mean daily intakes were well below ADI for all three metals (Cd 0.73 of 6 µg, Pb 0.85 of 20 µg, As 0.67 of 10 µg), yet 3 of 277 products (1.1%) individually exceeded an ADI (two for cadmium, one for lead). The contamination-determinant structure is the paper’s distinctive contribution: cadmium and arsenic intake rose significantly with herbal/probiotic/enzyme/fatty-acid formulations and with powder/liquid and soft-gel dosage forms, while lead was significantly higher in India-manufactured products. The authors conclude that formulation category, dosage form, and country of origin are strong determinants of supplement metal contamination.

Key numbers

Values are estimated daily metal intake (µg/day) = product concentration (µg/g) × labelled daily dose, by ICP-MS. ADI as cited by the authors (American Herbal Products Association guidance). Arsenic is total As (no speciation).

• Overall 3 of 277 products (1.1%, 95% CI −0.14 to 2.3) exceeded an ADI for Cd, Pb, and/or As.
• Cadmium intake rose significantly (p < 0.001) with herbs+probiotics+enzymes+fatty-acid formulations (β = 0.876) and herbs+vitamins+minerals+fatty-acids+enzymes (β = 0.725); and with powder/liquid and soft-gel forms (p = 0.030).
• Lead intake was significantly higher in India-made products (multivariate β = 1.599, p < 0.001) and lower in capsule form (β = −0.75, p = 0.002).
• Arsenic intake rose with powder/liquid form (β = 1.65, p < 0.001), soft-gel form (β = 0.52, p = 0.003), and herbal/probiotic/enzyme/fatty-acid blends (β = 0.53, p = 0.005).
• LOQ 50 µg/g (Pb, As), 10 µg/g (Cd); validated spike recovery 80–120%, RSD < 20%.

Methods (brief)

ICP-MS (Agilent 7700X) with He collision/reaction cell after CEM MARS-5 microwave acid digestion (HNO₃ + H₂O₂ + HCl). Random-selection sampling of 277 orally-taken supplements across UAE outlets. Per-product concentration converted to daily intake via labelled adult dose; means/medians compared to ADI; univariate and multivariate linear regression for contamination determinants (formulation category, dosage form, country of origin). QC: reagent blanks, matrix spikes every 15 samples, calibration verification every 10–15 samples.

Implications

• Primary, large-n (277) occurrence/exposure dataset for Dietary Supplements and Ingredient class — botanicals/herbs/traditional formulas, anchoring Cd/Pb/As daily-intake distributions and the formulation/dosage-form/origin determinants.
• Identifies formulation (herbal/probiotic/enzyme/fatty-acid blends), dosage form (powder/liquid and soft-gel), and country of origin (India for Pb) as covariates significantly associated with metal intake from supplements in this sample.
• Contributes Cadmium, Lead, and Arsenic occurrence in supplements with a quantified low-exceedance rate (1.1%).

Wiki pages this source may touch

• Dietary Supplements and Ingredient class — botanicals/herbs/traditional formulas — Cd/Pb/As daily-intake distribution and contamination determinants.
• Cadmium — herbal/probiotic formulation and soft-gel/powder association.
• Lead — India-origin association.
• Arsenic — powder/liquid and soft-gel association.

Verification notes

• Values from Table 2 (overall daily intake) and Tables 3–6 (determinant regressions). Table 2’s header label “µg/g” conflicts with the body text and ADI comparison, which are in µg/day intake; the abstract and Results consistently state µg/day, so daily intake (µg/day) is recorded here and the “µg/g” header is treated as a typographical error.
• Reported metric is daily intake (concentration × labelled dose), not raw µg/g concentration, so this is occurrence expressed through an exposure lens; underlying per-product µg/g concentrations are not separately tabulated.
• No brand-by-brand data: results are aggregated by formulation category, dosage form, and country of origin; the Part 12 firewall is satisfied at the source.
• Speciation: total As by ICP-MS; no inorganic-As fraction reported.
• Matrices vocabulary: dietary-supplement is in the common-matrices list in docs/gpt-collaboration/system-prompt.md; herbal-supplement and vitamin-mineral-supplement are added as broader-than-product matrix descriptors that follow the same naming convention but are not yet in the common-matrices list. Surfacing for next matrices-vocabulary refresh.
• Audit subagent (2026-06-09) ran the five-check audit against the PDF; verdict REVISE; applied corrections: (a) Check 1 — moved the p<0.001 parenthetical off the herbs+probiotics clause and onto the powder/liquid clause in the As multivariate (Table 6 powder/liquid is p<0.001, soft-gel is p=0.003, herbs+probiotics is p=0.005); (b) Check 2 — added matrices-vocabulary flag above; (c) Check 5 — softened “directly actionable pattern for category screening” (Summary) and “concrete screening levers for any future certification” (Implications) toward literature-fidelity framing per Part 2 wiki/HMTc firewall.

Page history

The five most recent substantive edits to this page. The full version history lives in git; when DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.