Cheyns et al. 2021 - arsenic species in algae and cyanobacteria supplements

Cheyns and colleagues measured total arsenic and selected arsenic species in 33 algae- or cyanobacteria-based food supplements purchased in Belgium. The source is directly relevant to algae/seaweed supplement occurrence because it reports sample-level total As, inorganic As, DMA, arsenobetaine, recommended dose, and exposure estimates. All sample results are reported on a whole-weight, product-as-sold basis.

Key numbers

The abstract reports total As (Astot) concentrations in the range 0.053-57 mg/kg, with the highest concentrations in supplements containing brown algae. Inorganic As (Asi) concentrations were reported in the range <0.02-4.7 mg kg−1. The paper states that a large fraction of arsenic in algae/cyanobacteria supplements was present as arsenosugars and that negligible amounts of arsenobetaine were detected.

Table 1 reports concentrations in µg g−1. All rows below preserve the source’s sample IDs and units; no brand names are reported in the source.

The source’s exposure calculation used package-recommended daily dose and a 70 kg adult body weight. It reports daily supplement-derived Asi intake in the range 0.00004-0.02 µg kgbw−1 d−1, potentially toxic As fraction (Astot-AB) intake in the range 0.00012-0.20 µg kgbw−1 d−1, and DMA intake in the range 0.00008-0.011 µg kgbw−1 d−1.

Selected source risk-screen outputs, reported here as source context rather than HMTc thresholds:

• The highest calculated Asi exposure, including background exposure, was 2.6% of the source’s acute MRL screen.
• The highest calculated DMA exposure, including background dietary exposure, was 0.1% of the chronic MRL screen.
• For Asi, the source concluded no concern for the general population across all collected supplements, while 8 of 33 supplements were classified as of concern for the source’s sensitive-population screen.
• For the Astot-AB potentially toxic fraction, the abstract states 26 out of 33 supplements showed no concern and 7 had potential health risk. The body text states 24 out of 33 (= 79%) showed no concern and 7 had potential health risk; the percentage and complement align with 26/33, so the inconsistency is preserved rather than resolved here.

Methods (brief)

Thirty-three algae/cyanobacteria food supplements were purchased from local and online stores in Belgium during 2013-2016 and analyzed within six months after purchase. For each supplement, at least 10 tablets, capsules, or soft gels were homogenized; liquid supplements were homogenized by shaking, and dry formulations were ground before extraction or mineralisation. Soft-gel and capsule casings were separated from contents because of heterogeneity problems; for worst-case exposure calculations, the authors initially assumed casing concentrations equaled content concentrations.

Total As was determined by ICP-MS after acid digestion in PTFE vessels in a microwave oven. Arsenic species were extracted with 0.10 M HNO3 and 3% hydrogen peroxide, following a procedure similar to EN 16802:2016; this oxidizes As(III) to As(V), so Asi is measured as total inorganic arsenic without distinguishing oxidation state. Speciation was performed by HPLC-ICP-MS. The LOQ for Asi and DMA on the anion-exchange method was 0.020 mg kg−1, and the LOQ for AB on the cation-exchange method was 0.092 mg kg−1. CRMs included NMIJ 7405a hijiki seaweed, NMIJ 7532 brown rice flour, BCR 627 tuna fish, BCR 729 sea lettuce, and IRMM 804 rice flour.

Implications

This source provides a primary, sample-level occurrence dataset for algae and cyanobacteria supplements on an as-sold basis. It is especially important because it separates total arsenic from inorganic arsenic and DMA, and because the brown-algae/kelp subset shows higher total arsenic while individual samples vary substantially in inorganic arsenic. The page should not be used to infer brands or product rankings; the source anonymizes samples as FS1-FS33 and reports ingredient/species categories rather than brand-linked contaminant values.

Wiki pages this source may touch

• supplements-algae-seaweed-based
• dietary-supplements
• seaweed
• herbal-botanicals
• arsenic-total
• arsenic-inorganic

Verification notes

• Identity checks before writing found no existing source page for DOI 10.1080/19440049.2021.1877834, raw handle MFK_cheyns2021, title text, or cite key cheyns2021-algae-cyanobacteria-supplements-arsenic.
• All sample-level concentration values in the Key numbers table were rechecked against /tmp/hmi-seaweed-032.txt, extracted with pdftotext -layout. The rows are copied from Table 1 in source order; na and < censoring markers are preserved.
• Units are preserved as the source reports them: Table 1 concentrations are µg g−1, abstract and text ranges use mg/kg or mg kg−1, and exposure values use µg kgbw−1 d−1. No unit conversion was performed.
• Speciation check: Astot is recorded as total arsenic; Asi is the source’s measured inorganic arsenic fraction after extraction/oxidation; DMA and AB are not collapsed into total or inorganic arsenic. The Astot-AB metric is the source’s potentially toxic fraction, not a measured inorganic-arsenic value.
• Brand firewall: the page retains only anonymized source sample IDs (FS1-FS33) and species/formulation categories; no brand names or retailer names are attached to values.
• Missing-slug note: the taxonomy snapshot has no exact ingredient slugs for Chlorella, Spirulina, cyanobacteria, Ascophyllum, Fucus, Macrocystis, or Lithothamnium. Frontmatter uses broad existing seaweed, herbal-botanicals, supplements-algae-seaweed-based, and dietary-supplements slugs; exact organism names remain in source text.

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.