Al-Dhabi 2013 - metals in commercial Spirulina supplements

Al-Dhabi measured nickel, zinc, mercury, platinum, magnesium, and manganese in 25 commercial Spirulina products sold for direct human consumption. The study sampled tablets and capsules from seven declared countries of origin, digested powdered product material, and quantified elements by ICP-MS. Values are reported on a dry-weight basis in mg/kg d.w.; mercury is reported only as Hg with no methylmercury speciation, so this page records it as total mercury (tHg).

Key numbers

Sample frame: 25 Spirulina supplement products, including 16 tablet products and 9 capsule products. The paper lists product codes, manufacturers, and countries of origin; the Key numbers below aggregate to the Spirulina supplement category and do not reproduce brand/manufacturer-linked values.

Table 2 and the abstract report the following concentration ranges in mg/kg d.w.:

The paper states that all mercury values were <0.03 mg/kg d.w.. It also reports that the most abundant measured metals in the Spirulina samples were zinc and nickel, while mercury and platinum were the least abundant measured analytes.

Table 3 reports two statistically significant positive correlations at the paper’s stated critical r = 0.725 threshold: Hg with Ni (r = 0.751) and Mg with Hg (r = 0.733), with P < 0.005.

The authors cite recommended daily-intake values in Table 4 (Ni 0.4, Zn 13, Hg 0.01, Pt 0.002, Mg 400, Mn 4 mg/daily) and conclude that the sampled products did not exceed those source-side intake comparators. Those source-side comparators are recorded here only as part of the paper’s interpretation, not as HMTc thresholds.

Methods (brief)

The study obtained 25 Spirulina products from specialist shops. Tablet samples were ground with a mortar and pestle; capsule shells were removed and the powders used directly. Triplicate 100 mg powder portions were digested in Teflon PFA vessels with 65% HNO3 using a CEM MDS-200 microwave system. Elemental determination used ICP-MS on a Perkin Elmer Elan-6000 with certified reference materials from Merck used to prepare standard solutions. The paper reports forward power 1400 W, nickel sample and skimmer cones of 1.0 mm and 0.75 mm, sample flow 1.0 ml/min, and survey scanning from 4-245 amu.

Implications

This source adds a small, original occurrence dataset for algae-based dietary supplements, specifically Spirulina tablets and capsules. It is most useful for the supplements-algae-seaweed-based and broad dietary-supplements product rows because it measures products marketed for direct human consumption rather than cultivation biomass or environmental algae. The study did not measure arsenic, cadmium, lead, chromium, or methylmercury; it should therefore not be used to fill those analyte distributions for Spirulina supplements.

Wiki pages this source may touch

• supplements-algae-seaweed-based
• dietary-supplements
• supplements-oral-solids-tablets
• supplements-oral-solids-capsules
• nickel
• zinc
• mercury-total
• platinum
• magnesium
• manganese

Verification notes

• Identity checks before writing found no existing source page for DOI 10.1016/j.sjbs.2013.04.006, raw handle MFK_al-dhabi2013, title text, or cite key al-dhabi2013-spirulina-products-metals.
• All Key numbers were rechecked against /tmp/hmi-seaweed-025.txt, extracted with pdftotext -layout. The concentration ranges match the abstract and Table 2, and the sample count/form split matches the Methods text.
• Units and basis are preserved as mg/kg d.w.; no dry-to-wet or dose conversion was performed. The paper’s Table 4 daily-intake comparators are quoted only as source-side interpretation.
• Speciation check: Hg is not speciated and is recorded as tHg. The paper does not report MeHg, inorganic mercury, arsenic, cadmium, lead, or chromium data.
• Brand firewall: Table 1 lists product codes, manufacturers, and countries of origin, but this page does not reproduce brand/manufacturer names or attach contamination values to product codes. Values are summarized at the Spirulina supplement category level.
• Missing-slug note: the taxonomy snapshot has no exact spirulina ingredient slug. Following the existing Spirulina/Chlorella source-page convention, ingredients: [] is left blank while products route to algae/seaweed supplements and dietary-supplement oral solid rows.

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.