Submitted to: Biological Trace Element Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/24/2003
Publication Date: 5/1/2004
Citation: Finley, J.W., Grusak, M.A., Keck, A., Gregoire, B.R. 2004. Bioavailability of selenium from meat and broccoli as determined by retention and distribution of se75. Biological Trace Element Research. 99:191-209.
Interpretive Summary: Supplemental selenium, an essential nutrient, may reduce the risk of cancer. Selenium-enriched foods may be an ideal means of supplementing selenium intakes. Broccoli and beef were produced in a manner that resulted in high concentrations of selenium in the edible portions. These foods were incorporated into rat diets and rats were also fed a meal of meat or broccoli that was labeled with radioactive selenium. After 10 days, the rats were killed and radioactive selenium was measured in individual tissues and organs. In rats that were fed a normal amount of selenium, radioactive selenium from meat was retained much better than radioactive selenium from broccoli. Also, radioactive selenium from meat was used to make selenium proteins, whereas radioactive selenium from broccoli was not. When rats were fed high amounts of selenium, most of the differences betwween selenium from broccoli and meat disappeared. These results demonstrate that high-selenium beef may be an excellent source of supplemental selenium for people seeking to improve their selenium intake. They also demonstrate that selenium from broccoli is utilized in a different manner and more work is needed to characterize the advantages and disadvantages of this source of selenium.
Technical Abstract: Because of its putative anti-cancer properties, many people are seeking to consume supplemental selenium (Se). Foods contain variable amounts of Se depending on where they are produced and meat and broccoli are two foods that may accumulate substantial amounts of Se when produced in high-Se areas. Selenium from broccoli is not as well retained or incorporated into selenoproteins as other forms of Se, but it is very effective for reducing the risk of colon cancer. Selenium from meat has been demonstrated to be well retained but its cancer protective benefits are not known. In a further attempt to characterize the bioavailability and utilization of Se from meat and broccoli, we have fed rats diets adequate or high in Se and then given them a test meal of broccoli or meat intrinsically labeled with Se75. When dietary Se was adequate (0.1 ug/g diet), more Se75 from meat was retained than Se75 from broccoli. However, there were fewer differences in retention when dietary Se was high (1.5 ug/g diet). A significantly greater percentage of Se75 from broccoli was excreted in the urine than from meat. There did not appear to be homeostatic control over the amount of Se from broccoli excreted in urine, but the amount excreted from meat varied depending on dietary Se intake. Se75 derived from meat effectively labeled selenoproteins in all tissues examined, but Se75 from broccoli was undetectable in selenoproteins. These data demonstrate basic differences in the metabolism of Se from meat and broccoli. Such differences must be taken into account when a food is recommended as a source of supplemental Se.