Prevention of spontaneous prostate-related cancer in Lobund-Wistar rats by a soy protein isolate – isoflavone diet

Author: Pollard M, Wolter W
Publication: Prostate 2000 Oct 1;45(2):101-5

Epidemiological studies have demonstrated that Japanese and Chinese men, who consume a lot of soy, have less risk to develop prostate cancer than men form Europe or USA, who consume very little soy. This observation might be explained by the action of the soy isoflavones.

Test were conducted on special breed of rats: the Lobund-Wistar rats. These rats produce higher levels of the hormone testosterone, which is known to promote the development of cancers. About 30% of the Lobund-Wistar rats will develop spontaneously metastasizing adenocarcinomas in the prostate, which will develop in a prostate tumor.

About 200 Lobund-Wistar rats were divided in two groups, and were fed during 2-24 months on 2 different diets:

– Group 1: received natural diet containing soy meal
– Group 2: received same diet but soy protein was replaced with casein (milk protein)

After 24 months, 3% rats of group 1 and 30% rats of group 2 developed prostate cancers. These results suggest that soy meal contained a factor, probably isoflavones which have an agonist effect.