Does B12 affect cancer?

Many people wonder if B12 has any effect on cancer.  It seems obvious, since B12 is needed for the proper switching on and off of genes in the DNA and cancer is almost certainly caused when the genes don't switch off when they should.  But we hadn't found any direct evidence of this.

Well here it is.

The first paper we were alerted to (by Jeffrey Spector) describes the effect clearly.  Nishizawa et al tested two hypotheses: that B12 had an effect on a cell culture (ie in a test tube), and that it had the same effect in the mouse.

Firstly, in the test tube, they showed that (to quote from the Abstract) "Methylcobalamin inhibited the proliferation of androgen-sensitive SC-3 cells (a cloned cell line from Shionogi mouse mammary tumor, SC115) in culture at the concentration of 100-300 micrograms/ml" (for an average human, that would be 100million ng/L).

Then, in mice on B12 deficient diets, which develop cancer in any of the sex-hormone sensitive cells (ie typically the reproductive organs but also organs of secondary sexual characteristics - in humans this would be the deepening of the voice etc in males but I don't know what it would be in mice :) ), they showed that not only did it inhibit tumour growth (ie cure the cancer) but that it was also completely safe at these very high levels.

Nishizawa, Y., T. Yamamoto, et al. (1997). "Effects of methylcobalamin on the proliferation of androgen-sensitive or estrogen-sensitive malignant cells in culture and in vivo." Int J Vit Nutr Res 67(3): 164-170.

The second study is from the same author (Y Nishizawa) although by this time she or he is the professor and G H Goto is the first-named author.

This one attempts to discover the exact way that methylcobalamin works.  Basically they seem to be saying that the cells know that they aren't 'proper' body cells, so when the B12 comes along, they commit suicide even though they have plenty of the FGF-8 to stimulate them to grow uncontrollably.

Apart from showing how B12 works, it also illustrates just how amazing the body and living things are, and there's still this very difficult question "how does the cell know that it isn't a 'proper' body cell?

Goto, G. H., H. Katayama, et al. (2008). "Methylcobalamin inhibits fibroblast growth factor-8 stimulated proliferation and induces apoptosis in Shionogi carcinoma cells." Int J Vit Nutr Res 78(1): 21-26.