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A new look at the purported health benefits of commercial and natural clays

Incledion, Alexander, Boseley, Megan, Moses, Rachael L., Moseley, Ryan ORCID:, Hill, Katja E. ORCID:, Thomas, David W., Adams, Rachel A. ORCID:, Jones, Tim P. ORCID: and Berube, Kelly A ORCID: 2021. A new look at the purported health benefits of commercial and natural clays. Biomolecules 11 (1) , 58. 10.3390/biom11010058

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Clays attributed to have medicinal properties have been used since prehistoric times and are still used today as complementary medicines, which has given rise to unregulated “bioceutical” clays to treat skin conditions. Recently, clays with antibacterial characteristics have been proposed as alternatives to antibiotics, potentially overcoming modern day antibiotic resistance. Clays with suggested antibacterial properties were examined to establish their effects on common wound-infecting bacteria. Geochemical, microscopical, and toxicological characterization of clay particulates, their suspensions and filtered leachates was performed on THP-1 and HaCaT cell lines. Cytoskeletal toxicity, cell proliferation/viability (MTT assays), and migration (scratch wounds) were further evaluated. Clays were assayed for antibacterial efficacy using minimum inhibitory concentration assays. All clays possessed a mineral content with antibacterial potential; however, clay leachates contained insufficient ions to have any antibacterial effects. All clay leachates displayed toxicity towards THP-1 monocytes, while clay suspensions showed less toxicity, suggesting immunogenicity. Reduced clay cytotoxicity on HaCaTs was shown, as many leachates stimulated wound-healing responses. The “Green” clay exhibited antibacterial effects and only in suspension, which was lost upon neutralization. pH and its interaction with clay particle surface charge is more significant than previously understood to emphasize dangers of unregulated marketing and unsubstantiated bioceutical claims.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Dentistry
Earth and Environmental Sciences
Cardiff Institute Tissue Engineering Repair (CITER)
Additional Information: This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (
Publisher: MDPI
ISSN: 2218-273X
Date of First Compliant Deposit: 5 January 2021
Date of Acceptance: 31 December 2020
Last Modified: 11 Oct 2023 18:51

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