Maisto et al. 2024 - Polyphenol formulations and heavy-metal bioaccessibility
Maisto and colleagues tested whether water-soluble maltodextrin formulations of quercetin, ellagic acid, curcumin, or a mixed formulation changed heavy-metal bioaccessibility during simulated gastrointestinal digestion. This is primary in vitro health/testing evidence, not food, ingredient, or product occurrence evidence. The source’s routeable concentration facts are the standardized metal-spiked water concentrations, AAS method limits, and measured duodenal bioaccessible fraction (DBF) versus non-bioaccessible fraction (NBF) shifts.
Key numbers
Standardized metal solution and method limits
The standardized heavy-metal water solution was prepared at Cr 50 ng/mL, Ni 50 ng/mL, Hg 100 ng/mL, Pb 100 ng/mL, Cd 10 ng/mL, As 100 ng/mL, Sr 100 ng/mL, Sb 100 ng/mL, Zn 10 ng/mL, Cu 10 ng/mL, and Fe 10 ng/mL. Because 1 ng/mL equals 1 ug/L, these are also the initial ug/L concentrations before digestion and fractionation. The reported DBF/NBF results focus on Hg, Cd, As, Cu, Pb, Sb, Zn, and Fe.
Table 1 reports AAS detection limits of 0.0001 mg/L for Hg, As, and Cu; 0.0003 mg/L for Cd; 0.001 mg/L for Pb, Zn, and Fe; and 0.002 mg/L for Sb. Linear calibration ranges were 0-20 ppb for Hg, As, Cu, Pb, Sb, Zn, and Fe, and 0-10 ppb for Cd.
Formulation properties
The maltodextrin formulations had high water solubility after encapsulation: MQE 91.32 +/- 1.23%, MEA 93.45 +/- 2.11%, and MCUR 89.32 +/- 1.98%, compared with the native extract solubilities QE 4.12 +/- 0.01%, EA 7.52 +/- 0.02%, and CUR 3.21 +/- 0.09%. Encapsulation efficiency was 89% for MQE, 91% for MEA, and 82% for MCUR. Moisture contents were 3.11 +/- 0.02%, 2.11 +/- 0.02%, and 3.56 +/- 0.02% for MQE, MEA, and MCUR, respectively.
MQE had the strongest antioxidant activity, with IC50 values of 24.14 ug/mL in the DPPH assay and 29.53 ug/mL in the ABTS assay. The authors use this antioxidant/chelation relationship to interpret the stronger non-selective metal precipitation observed for MQE.
Toxic metal bioaccessibility
Figure 4 reports DBF and NBF concentrations in ug/L for Hg, As, Cd, Pb, and Sb after simulated digestion. The paper’s exact text-reported NBF changes versus control are:
| Treatment | Toxic-metal NBF findings vs control |
|---|---|
| MCUR | Cd +25.2% (not significant), As +33.1%, Hg +11.9% (not significant), Pb +263.7%, Sb +109.1% |
| MQE | Cd +68.3%, As +51.9%, Hg +58.9%, Pb +271.4%, Sb +111.2% |
| MEA | Cd +23.9% (not significant), Hg +31.9%, Pb +58.4%, Sb +47.6%; no arsenic percentage is stated in the text |
| MIX | Pb +223.9%, Sb +74.8%, Hg +33.9%, As +22.5% (not significant); no cadmium percentage is stated in the text |
Graph-read approximate control concentrations in Figure 4 are about Hg DBF 47 ug/L and NBF 51 ug/L, As DBF 48 ug/L and NBF 52 ug/L, Cd DBF 4.8 ug/L and NBF 4.8 ug/L, Pb DBF 77 ug/L and NBF 22 ug/L, and Sb DBF 60 ug/L and NBF 38 ug/L. These approximations are recorded only to orient the figure scale; the paper’s exact routeable statements are the initial standardized concentrations and text-reported percentage changes.
Essential metal bioaccessibility
For the control digestion, the authors report in vitro bioaccessibility of Zn 33.7%, Cu 42.1%, and Fe 53.3%. Figure 5 reports DBF/NBF concentrations for these elements and the text reports the following DBF changes versus control:
| Metal | Treatment findings |
|---|---|
| Zn | MEA increased DBF by 68.5%; MIX increased DBF by 62.1%; MCUR increased DBF by 55.8%; MQE did not increase Zn bioaccessibility |
| Cu | MEA increased DBF by 105.6%; MQE was -1.4% and not significant; MCUR increased DBF by 52.6%; MIX increased DBF by 42.9% |
| Fe | MCUR increased DBF by 29.2%; MEA increased DBF by 29.4%; MIX increased DBF by 21%; MQE did not significantly change Fe DBF or NBF |
Graph-read approximate control concentrations in Figure 5 are about Zn DBF 3.3 ug/L and NBF 6.5 ug/L, Cu DBF 4.2 ug/L and NBF 5.7 ug/L, and Fe DBF 5.3 ug/L and NBF 4.6 ug/L.
Methods (brief)
The authors prepared maltodextrin-encapsulated powders from quercetin-, ellagic-acid-, and curcumin-rich extracts by freeze-drying. A standardized multi-element water solution was treated with each formulation or the mixed formulation, then subjected to sequential oral, gastric, and intestinal digestion using an INFOGEST-style in vitro procedure. After intestinal incubation, samples were centrifuged and separated into supernatant (DBF) and pellet (NBF), freeze-dried, microwave digested with nitric acid and hydrogen peroxide, and analyzed by atomic absorption spectrophotometry. Results were reported as mean +/- standard deviation from three replicates, with one-way ANOVA and Tukey post hoc testing.
Implications
Certification: This source should not be pooled into food, ingredient, or product occurrence distributions. It uses artificial standardized water rather than market samples, and it manipulates bioaccessibility through added polyphenol formulations.
Courses: Useful for explaining why total concentration and bioaccessible concentration can diverge after digestion, and why chelating ingredients may shift toxic metals into a non-bioaccessible pellet while increasing bioaccessibility for some essential elements.
App: Keep as health/testing context for metal bioaccessibility and chelation. Do not route the standardized spike concentrations to drinking-water occurrence pages, and do not route the formulation results to turmeric, pomegranate, or dietary-supplement occurrence rows.
Wiki pages this source may touch
Verification notes
The PDF has author attribution and DOI 10.3390/antiox13050610; no DOI conflict was observed. The paper is internally inconsistent on formulation dose: Section 2.8 says 1 g of each maltodextrin-based formulation was added to the 12.5 mL standardized metal solution, while Section 3.3 says 1 mg was dissolved in 12.5 mL. This page preserves the contradiction and does not infer the intended unit. The source reports total As and total Hg, not inorganic arsenic or methylmercury. Figures 4 and 5 provide concentration bars with standard deviations; this page records graph-read approximations only where the numeric labels were not printed, and uses the text-reported percentage changes for exact claims.
Merge-enhance pass 2026-06-02: matrices field normalized from study-specific descriptors to neighbor-consistent vocabulary (standardized-water, in-vitro-digestion, polyphenol-formulation), aligning with related in-vitro bioaccessibility sources (liu2023-arsenic-seafood-digestion, de-paiva-2020-aluminium-infant-foods-bioaccessibility, nencioni2026-zeolite-cream-metal-adsorption). Empty products and ingredients arrays are correct: the source uses artificial standardized metal-spiked water, not a food, ingredient, or product sample, so routing-malformed advisory severity is the appropriate steady state for this page.
Audit subagent (2026-06-02) flagged the calibration-range sentence as ambiguous; verified against Table 1 — only Cd uses the 0-10 ppb linear range while Hg, As, Cu, Pb, Sb, Zn, and Fe all use 0-20 ppb. Sentence rewritten to state ranges precisely.
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.
| Commit | Date | Description |
|---|---|---|
| c1aef38 | 2026-06-02 | audit-queue: hamid2021-bacterial-plant-biostimulants-review → audited-promote |