Comments? -------- There appears to be a link between megadoses of vitamin B12 and certain cancers. One study showed that excess vitamin B12 intake was associated with a three-fold increase in risk of developing prostate cancer. http://psa-rising.com/eatingwell/vb12_folate04.html Folate and B12 were expected to be protective against prostate cancer, because folate, vitamin B12 and homocysteine are essential for methyl group metabolism and thus also for DNA methylation. Abnormal methylation, primarily hypermethylation of certain genes including tumor suppressors, has been implicated in prostate cancer development. But in fact, increasing plasma levels of folate and vitamin B12 were statistically significantly associated with increased prostate cancer risk, with an odds ratio of 1.60 for folate and 2.63 for vitamin B12 for highest vs. lowest quartile. Increasing plasma homocysteine levels were associated with a reduced risk of borderline significance. After adjustment for body mass index and smoking, a statistically significant increased risk remained only for vitamin B12. The researchers say: "Our results suggest that factors contributing to folate status are not protective against prostate cancer. On the contrary, vitamin B12, associated with an up to 3-fold increase in risk, and possibly also folate, may even stimulate prostate cancer development. These findings are novel and should be explored further in future studies."