Submitted to: Molecular Mechanisms of Metal Toxicity Conference
Publication Type: Abstract Only
Publication Acceptance Date: January 20, 2006
Publication Date: September 25, 2006
Citation: Anderson, R.A. 2006. Safety of trivalent chromium complexes used in nutrient supplements. Molecular Mechanisms of Metal Toxicity Conference, Morgantown, WVA. 4:1:2006. Technical Abstract: Toxicity studies regarding trivalent chromium have often been completed under conditions that are not designed to reflect conditions that would be encountered under normal physiological conditions. We have shown that the incorporation of chromium into tissues of rats from chromium chloride and chromium picolinate is linear in the range of intake from 5 to 100 micrograms (ug) per gram of diet. On a per kg body weight basis, this would be roughly a daily intake of 5000 ug/kg compared with less than 15 ug/kg for a person consuming 1000 ug per day of supplemental chromium. Recent studies in mice suggest that at diets of close to 5000 ug of Cr as chromium picolinate per kilogram body weight given to pregnant mice could lead to signs of toxicity in the offspring. These values are clearly not within a realistic range of what could be expected for people taking 1000 'g of supplemental chromium. Studies involving unprotected DNA show that chromium binds to the DNA and leads to DNA damage. However, there are protective mechanisms that usually do not allow high concentrations of chromium to come in contact with DNA under normal conditions. There are also reports that chromium in the form of chromium picolinate can lead to free radical DNA damage in the presence of oxidants such as hydrogen peroxide. We subjected human cultured HaCaT keratinocytes to cytotoxic levels of chromium chloride and chromium histidinate (the highest soluble levels of chromium picolinate did not cause cell toxicity) for 24 hours and then submitted cells to hydrogen peroxide-induced oxidative stress and did not observe DNA damage. In contrast, we observed significant protective effects on DNA monitored by a decrease in % tail moment in the Comet assay.