Positive Health Online

Abstract

FINLEY and DAVIS, United States Department of Agriculture, Agricultural Research Service, Grand Forks Human Nutrition Research Center, ND 58202, USA, jfinley@gfhnrc.ars.usda.gov, investigated the ability of foods high in selenium (Se) to reduce the incidence of chemically induced colon cancer in a rat model.

Background

Methodology

Foods examined were high-Se broccoli (produced in a greenhouse by addition of selenate to the media surrounding the plant roots) and a processed high-Se wheat product (made by milling high-Se wheat purchased from a seleniferous area). The rats were fed diets containing different amounts of Se from these foods or from selenium salts (selenite and selenate ). Early in the study, the rats were injected with a chemical carcinogen. After 11 weeks on the diets, colons were examined for preneoplastic lesions (aberrant crypts foci, ACF).

Results

ACF were significantly reduced in rats fed supra-nutritional amounts of Se from broccoli, despite the finding that Se from broccoli was poorly bioavailable. Supra-nutritional amounts of Se from high-Se processed wheat also significantly reduced aberrant crypts (AC), although pure selenomethionine (the predominant chemical form of Se in wheat) did not significantly reduce AC.

Conclusion

The findings emphasize the need to study Se in food forms and not extrapolate from previous cancer inhibition studies using pure chemical forms. They also demonstrate that foods high in Se bioavailability are not necessarily the most efficacious for cancer incidence reduction.

References

Finley JW, Davis CD. Selenium (Se) from high-selenium broccoli is utilized differently than selenite, selenate and selenomethionine, but is more effective in inhibiting colon carcinogenesis. BioFactors 14 (1-4): 191-6. 2001.