Submitted to: Meeting Abstract
Publication Type: Abstract only
Publication Acceptance Date: 7/15/2005
Publication Date: 8/17/2005
Citation: Finley, J.W. 2005. Glucosinolates and selenium in the fight against cancer [abstract]. Presented at FAV 2005, Quebec City, Quebec, Canada, Aug 17 - 20, 2005. Interpretive Summary:
Technical Abstract: Broccoli (Brassica oleracea) is a rich source of phytochemicals that may reduce the risk of cancer. Among the most important compounds are glucosinolates, phytochemicals that may be converted by enzymatic action to isothiocyanates. Sulforaphane (Sf), the isothiocyanate derivative of glucoraphanin, is found in high concentrations in many varieties of broccoli and has biochemical activity that is associated with cancer chemoprotection. Additionally, broccoli can accumulate selenium (Se), and human intervention studies have reported that Se supplementation reduces the overall incidence of cancer, and specifically the incidence of prostate cancer in men. Studies have been conducted to determine whether Se enhancement of broccoli results in a plant food with superior chemoprotective properties. Broccoli with > 800 µg Se/g, as compared to broccoli with < 1 µg Se/g, inhibited early events in colon carcinogenesis in rats. However, increasing the Se content of broccoli also decreased the Sf content by more than 80%, and inhibited production of many phenolic acids. When fed to rats, broccoli induced the activity of the selenoprotein thioredoxin reductase beyond the maximum activity induced by Se alone, and the amount of induction depended on the ratio of Se:SF. Oxidative stress, as measured by the COMET assay, was decreased by Se and SF from broccoli, but protection was the greatest in rats fed broccoli with the highest concentrations of Se. These results emphasize that the potential benefits to health of broccoli are a result of complex interactions between multiple bioactive chemicals. Attempts to maximize one component of broccoli may affect accumulation of another, and consumption of high amounts of multiple bioactive compounds in broccoli may result in unexpected metabolic interactions within the body.