A study published November 18 in the Journal of the National Cancer Institute says that vitamin B12 is essential for maintaining healthy bodily function but higher than normal levels may indicate that a patient is at risk of developing certain cancers.
Previous studies had suggested an association between high Cbl levels and specific cancers.
To assess the association between high Cbl levels and risk of cancer of any type, Johan Arendt, BSc, of the Department of Clinical Epidemiology and the Department of Clinical Biochemistry of Aarhus University Hospital in Denmark, and colleagues used Danish Medical registries to review the records of 333,667 patients without cancer who had been referred for Cbl testing and to estimate the incidence of cancer in this population from 1998 to 2010.
The authors conclude that "...high plasma Cbl levels increased the risk of subsequently diagnosed cancer, mostly within the first year of follow-up." However, Arendt et al. note that high plasma Cbl levels are probably not related to normal Vitamin B12 intake because consumption of Cbl containing foods or supplements do not increase plasma Cbl levels substantially. Rather, high Cbl levels may result from some unknown malignant process.