A study by Awad and Fink suggests that beta sitosterol can improve some of the symptoms of prostatic hyperplasia. However this does not lead to prostate cancer and the amount they found to be significant was 60 mg of beta sitosterol. The study suggested that sterols may offer protection from cancer but further research is needed. This study was published in 2000. However a study published in 2001 by Normén AL, Brants HA, Voorrips LE, Andersson HA, van den Brandt PA, Goldbohm RA entitled "Plant sterol intakes and colorectal cancer risk in the Netherlands Cohort Study on Diet and Cancer" found that "A high dietary intake of plant sterols was not associated with a lower risk of colon and rectal cancers in the Netherlands Cohort Study on Diet and Cancer." This covered a sample size of 120,852 people over a little more than 6 years, and 620 colon and 344 rectal cancer cases were detected. Another study, by Jourdain C, Tenca G, Deguercy A, Troplin P, Poelman D, found that while beta sitosterol may have a small effect specifically on the growth of prostate cancer cells, polyphenols from cocoa have a greater effect. In other words, chocolate is better, as is often the case.

To be honest my interest in this only goes so far. I'm a software developer with pretty good research skills and a high boredom threshold rather than a biochemist. My main points are that Imunozen is a very expensive way to get hold of things like sterols that occur naturally in food, and a lot more research is needed to find a causal link between taking them and the effects claimed. Personally I'd go by the findings of the study by Jourdain et al and spend the money on a selection of goodies from Hotel Chocolat or Thorntons instead.