The purpose of this investigation was to determine how dietary levels of α-tocopherol, γ-tocopherol and iron influence oxidative stress and ras-p21 levels in the colon. Rats were fed diets deficient in tocopherols (-E) or supplemented with either 0.156 mmol of α-tocopherol (AE)/kg diet or 0.156 mmol of γ-tocopherol (GE)/kg of diet. Half the rats in each of these three groups received dietary iron at a level of 35 mg/kg diet and the other half at eight times this level (280 mg/kg diet). Rats fed the AE diets had higher levels of Vitamin E in feces, colonocytes, plasma and liver than did rats fed the GE diets. Dietary iron levels did not influence tocopherol levels in plasma, liver or feces. For colonocytes, high dietary iron decreased tocopherol levels. The ratio of γ-tocopherol (in the GE groups) to α-tocopherol (in the AE groups) was 0.13 for plasma, 0.11 for liver, 0.28 for colonocytes and 0.51 for feces. The plasma ratio is not, therefore, predictive of the ratio in colonocytes and feces. High levels of dietary iron increased levels of fecal lipid hydroperoxides. Moreover, rats fed the GE diets had lower levels of fecal lipid hydroperoxides than rats fed the AE diets. The levels of ras-p21 were significantly lower in rats fed the GE diets compared with rats fed the AE diets. The γ-tocopherol may, therefore, play a significant role in preventing colon cancer. High levels of dietary iron were found to promote oxidative stress in feces and colonocytes.
| Identifer | oai:union.ndltd.org:ETSU/oai:dc.etsu.edu:etsu-works-20225 |
| Date | 01 December 2002 |
| Creators | Stone, William L., Papas, Andreas M., LeClair, Irene O., Qui, Min, Ponder, Terry |
| Publisher | Digital Commons @ East Tennessee State University |
| Source Sets | East Tennessee State University |
| Detected Language | English |
| Type | text |
| Source | ETSU Faculty Works |
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