Findings and scope
The study gave 21 Australian adults either a complex calcium supplement (calcium citrate, phosphate and amino acid chelate; 920 mg calcium per day), a chewable calcium carbonate supplement (1,000 mg calcium per day) or no supplement for 6 months. It traced the supplement lead in blood by its isotopic signature (PDF p.1 to p.2). The carbonate product contained 700 µg/kg lead and the complex product 293 µg/kg, giving 3.2 and 2.8 µg lead per day at full compliance (Table 1, PDF p.2). Blood lead concentrations changed little in any group, and the group-by-treatment interaction for blood lead was not significant (p = 0.402, PDF p.3). Blood lead isotope ratios in the calcium carbonate group shifted toward the supplement’s ratio, with a significant difference from controls for 208Pb/206Pb (p = 0.008). The authors estimate the maximum contribution of the carbonate supplement to blood lead at less than 0.5% (PDF p.4). The complex product produced no detectable isotopic change.
Key numbers
Supplement lead as printed (Table 1, PDF p.2). The measurement basis is not stated.
| Product | Lead (µg/kg) | Daily lead intake (µg/day) | 206Pb/204Pb |
|---|---|---|---|
| Complex (citrate, phosphate, amino acid chelate) | 293 | 2.8 | 20.14 |
| Calcium carbonate, chewable | 700 | 3.2 | 19.70 |
Individual blood lead before treatment ranged from 1.2 to 5.8 µg/dL in subjects without anomalies; three subjects with outside lead exposures (paint renovation, firearms) ranged up to 7.8 µg/dL (Table 2, PDF p.3). These blood values are held as context only.
Methods and Evidence Fitness
Supplements were spiked with a 202Pb tracer, dissolved in ultra-pure nitric acid, and lead was separated by chelex and anion exchange before analysis by thermal ionisation mass spectrometry, giving lead concentration by isotope dilution (PDF p.2). Supplement procedural blanks were 300 to 900 pg and were judged negligible. Blood was processed in clean rooms by the same method. Isotope ratios were normalised to NIST SRM 981. The paper reports no reference material for lead concentration in a calcium matrix.
Evidence Fitness is Modeled or limited evidence for the supplement concentrations. The analytical method is strong, but there is one batch of each of two products and no stated basis. The blood measurements are context for exposure and uptake, not product occurrence. Assignment to groups was not fully random, because two subjects chose the control group.
Assessment limits
In Table 1 the isotope ratio, lead concentration and daily intake values sit under the calcium phosphate and calcium amino acid columns rather than under the complex and calcium carbonate headings. Attribution here follows the Figure 2 caption and the Discussion, which give a ratio of 19.7 for the calcium carbonate supplement and 20.14 for the complex supplement (PDF p.4). Tablet mass is not printed, so the daily intakes cannot be checked against the concentrations. The Methods describe the complex product as taken “3 times daily, with meals and at bedtime” (PDF p.2), while the Discussion says 4 times daily including at bedtime (PDF p.5). Compliance ranged from 0 to 100% per month (Table 2). Changes during treatment are printed as two-value spans whose order is not explained. Figures 2 and 3 show group means over time as charts only; these were not captured.
Provenance notes
The PDF (6 pages) was delivered in batch 05 of order HMI-GAP-INGEST-1 on 22 October 2026. The SHA-256 matches the batch manifest. The PDF does not print a DOI; it prints the citation Environ Health Perspect 109:283-288 (2001), which corresponds to manifest DOI 10.1289/ehp.01109283. The printed title matches the manifest title.
Related evidence
- Ingredient class — vitamin/mineral (single, multi-mineral, multi-vitamin/mineral)
- Lead in Calcium Supplements
- Lead
Update history
22 October 2026: Ingested from the batch-05 PDF. 4 supplement records and 51 blood-lead context records were added to the evidence register.
Update history
No substantive edit history is available in this build. The full commit record is available in git.