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Research: LANDSTROM and colleagues,
Listed in Issue 40
Abstract
LANDSTROM and colleagues, Department of Pathology, University of Umea, Sweden researched, in rats, the effect of diet treatments with soy flour and rye bran upon prostate tumour development .
Background
Methodology
125 rats with transplanted R3327 PAP prostate tumours were divided into five groups. Tumour development was studied for 24 weeks during treatment with diets containing: 1) 33% soy flour (SD); 2) rye bran (RB); 3) heat-treated rye bran (HRB); 4) rye endosperm (RE); 5) control, fibre-free dietary (FF).
Results
Compared with the control (FF), there were significantly fewer palpable tumours and lower tumour volume detected 14 and 16 weeks following transplantation in the SD (soy), RB (rye bran) and HRB (heat-treated rye bran) groups . Compared with the control, body weight was lower 16 weeks after transplantation in the RB and HRB groups. There was a significantly lower energy intake in the RB and HRB groups, compared with the controls during the 3-6 weeks following tumour transplantation, whereas energy intake was the same in all groups 13-16 weeks following transplantation. Even following adjustment of tumour volume for body weight, there were still significantly lower tumour volumes in the SD, RB and HRB groups compared with the FF controls. There was a significant increase in daily urinary excretion of the isoflavonoids daidzein, O-desmethylangolensin, equol and Genistein in the SD group, and of the ligands enterolactone and enterodiol in the RB and HRB groups. There were no differences in testosterone levels between the groups.
Conclusion
These data show that SD inhibits implanted prostate cancer growth . RB and HRB had a protective effect; however further studies are required to exclude the possibility that a low energy intake may have played a role in this regard. These results suggest that the phytoestrogens isoflavonoids and ligands may be responsible for the delayed prostate tumour growth .
References
Landstrom M et al. Inhibitory effects of soy and rye diets on the development of Dunning R3327 prostate adenocarcinoma in rats. Prostate 36(3): 151-61 1 Aug 1998.