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Chromium (III) - not only therapeutic?


Chromium is often cited as one element, showing extremely different biological effects depending on its valency state. While the Cr(III) species are considered essential for playing an important role in fat and glucose metabolism, Cr(VI) species have been identified as being toxic, causing cancer and DNA damage.

Cr(III) compounds are reported to have insulin-enhancing properties attributed to specific interactions with cellular insulin receptors. Unfortunately, the enhancing species containing chromium (Chromodulin) could not yet been isolated and identified. Anyhow, because of the reported beneficial effects, Cr(III) componds are often added to food supplements and total parenteral nutrition as a dietary supplement mostly in the form of its picolinate or nicotinate.

The Australian researchers focused their work on a well-characterized trinuclear oxo–carboxylato complex, [Cr(III)3O(CO2ET)6(OH2)3]+, named here as 'Complex A', which has been proposed as a structural and functional mimetic of chromodulin and a safer potential therapeutic agent than picolinate or nicotinate. The oxidation of this compound using H2O2 and ClO- under conditions similar to those found in the body was followed by using EPR spectra analysis which clearly indicated the formation of Cr(VI) compounds.

Tests on rats using Complex A, compared against tests using an alternative treatment with [Cr(III)(pic)3] ('Complex B'), showed that only Complex A worked as an efficient insulin activator. Since Complex A is also more easily oxidised than Complex B, this indicates that Cr(VI) production is involved in such activation.

The researchers conclude, that the ease of oxidation of Complex A to carcinogenic Cr(VI) under biologically relevant conditions warrants further research into the safety of using any Cr(III) compound as a nutritional supplement or therapeutic agent.

Michael Sperling

Original article:

 Irma Mulyani, Aviva Levina, A. Lay, Biomimetic Oxidation of Chromium(iii): Does the Antidiabetic Activity of Chromium(iii) Involve Carcinogenic Chromium(vi)?, Angew. Chem., 43/34 (2004) 4504-4507. DOI: 10.1002/anie.200460113

Related studies (newest first):

Aviva Levina, Peter A. Lay, Chemical Properties and Toxicity of Chromium(III) Nutritional Supplements, Chem. Res. Toxicol. 2008, 21, 563–571. doi: 10.1021/tx700385t

Maria A. Andersson, Kierstin V. Petersson Grawe, Oskar M. Karlsson, Lilianne A.G. Abramsson-Zetterberg, Björn E. Hellman, Evaluation of the potential genotoxicity of chromium picolinate in mammalian cells in vivo and in vitro, Food Chem. Toxicol., 45 (2007) 1097–1106. doi:10.1016/j.fct.2006.11.008


 Related EVISA resources:

Link database: Chromium as an essential nutrient
Link database: ATSDR: Toxicological Profile for Chromium
Link database: More about Cr(III)/Cr(VI)

 Related EVISA News

January 8, 2016: New study reports evidence for carcinogenic chromium(VI) compounds in chromium(III)-treated living cells
October 19, 2014: EFSA: No evidence for essentiality of chromium
August 18, 2014: New research indicates that chromium (III) is even more genotoxic than chromium (VI)
November 24, 2010: Deemed Essential to Health for Decades, Chromium Has No Nutritional Effect, UA Researchers Show 
May 23, 2007: Trivalent Chromium supplemention no help in controlling diabetes
April 24, 2007: Nutrigenomics: The role of chromium for fat metabolism revisited
September 15, 2005: FDA Approves Chromium Claim
March 20, 2005: United Kingdom's Food Standards Agency granted derogation to Chromium(III) compounds as a food supplement

last time modified: June 18, 2020


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