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Research connects chromium supplements with increased cancer risk

February 16, 2016

Researchers from The University of Sydney and UNSW have raised concerns over the long-term use of nutritional supplements containing chromium. The research team found that the supplement is partially converted into a carcinogenic (cancer causing) form when it enters human cells.

Chromium is a trace mineral found primarily in two forms: a range of chromium(III) forms sold as nutritional supplements and hexavalent chromium(VI), which is usually produced by an industrial process and is a known carcinogenic substance.

Controversy remains over whether the dietary form of chromium is essential, with an increasing body of evidence indicating it is not safe. Supplements containing chromium are consumed for the purported treatment of metabolic disorders, such as insulin resistance and type 2 diabetes, but chromium’s mechanism of action in the body is not well understood. These supplements are also commonly used for weight loss and body building.

In the study, the Australian researchers treated cells with chromium(III) before creating a map of every chemical element contained inside the cell. This was done by using an intense synchrotron X-Ray beam at the Advanced Photon Source (APS) in Chicago.  Experiments were also conducted at the former Australian National Beamline Facility at the Photon Factory in Japan which is operated by the Australian Synchrotron. This helped clarify the nature of the chromium(V) and chromium(VI) species formed in the cells, both of which can cause cancer.

Research lead Dr Lindsay Wu, from UNSW’s School of Medical Sciences, said the high energy synchrotron beam allowed the team to identify and classify chromium spots throughout the cell.

“The powerful X-Ray enabled us to determine whether the spots were chromium(III) or a combination of chromium(III), chromium(V) and chromium(VI).”

“The health hazards associated with exposure to chromium are dependent on its oxidation state – we were able to show oxidation of chromium inside the cell does occur, meaning it loses electrons and transforms into a carcinogenic forms, which no-one had been able to do in a biological sample before.”

Professor Peter Lay from the University of Sydney’s School of Chemistry said with the latency period for chromium(VI)-related cancers often greater than 20 years, the finding raises concerns over the possible cancer-causing qualities of chromium compounds and the risks of taking chromium nutritional supplements long term or in high doses.

“With questionable evidence over the effectiveness of chromium as a dietary supplement, these findings should make people think twice about taking supplements containing large doses of chromium.”

“However additional epidemiological research is needed to ascertain whether chromium supplements significantly alter cancer risk, since long-term laboratory experiments have not been conducted under the conditions of high oxidative stress (which promotes chromium(III) oxidation) associated with diabetes.”

The researchers said the findings are very unlikely to apply to trace amounts of chromium(III) found in food. The research has been published in the chemistry journal, Angewandte Chemie and has been supported by the Australian Research Council.

This news article was originally published on the Australian Synchrotron’s website. In 2015, the Australian Cancer Research Foundation awarded the Synchrotron AUD2m to expand its chrystallography (MX) beamline technology to speed up cancer drug discovery and development.

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