Positive Health Online

Abstract

HARRISON and colleagues, Beatson Institute for Cancer Research, CRC Beatson Laboratories, Glasgow, Scotland UK review (100 references) the very convincing evidence that a high dietary level of selenium significantly reduced the incidence of a wide variety of cancers in animals.

Background

Methodology

Results

The authors state that the human epidemiological evidence is less clear cut, but that overall it suggests that selenium may be protective, particularly in men in relation to gastro-intestinal cancers . There is evidence that dietary selenium reduces formation of DNA adducts by carcinogens, inhibit growth in vitro and induce apoptosis . There is good correlation between the effectiveness of selenium compounds in chemoprevention and growth inhibition, suggesting that the mechanisms of growth inhibition and chemoprevention may be similar and a key factor in the chemopreventive effects of selenium compounds in vivo may be their ability to retard outgrowth of pre-malignant cells . A number of hypotheses have been suggested regarding the mechanism by which selenium compounds may prevent tumour cell growth, including that they cause apoptosis by inducing oxidative stress. The authors have shown that selenodiglutathione (SDG) the most potent selenium compound and a metabolite of selenite, does not induce oxidative stress, at least not in the same manner as oxidants including H2O2 and diamide. A partially selenium-resistant variant cell line does not demonstrate increased resistance to H2O2 and SDG does not induce widespread tyrosine phosphorylation, including MAP and SAP kinases, like other oxidants such as H2O2 and diamide, and its effects are not reversed by pretreatment with herbimycin, the tyrosine kinase inhibitor.

Conclusion

: The authors experiments with the selenium-resistant variant suggest that a novel selenium-binding protein may be involved in growth inhibition by selenium.

References

Harrison PR et al. Chemopreventive and growth inhibitory effects of selenium. Biomed Environ Sci 10 (2-3): 235-45. Sep 1997 .