Elevated Vitamin B12, Risk of Cancer, and Mortality: A Systematic Review

Abstract

Vitamin B12 (B12) is a molecule involved in several biological. Abnormally high levels are frequently found, but their causes can be multiple, and consequences have not been clearly elucidated. The objective of this review was to summarize the current evidence on the associations of elevated B12 and the development of cancer, and all-cause mortality in adults. Six references looking at mortality and seven looking at cancer risk were included. The evidence suggests an association between elevated B12 with a higher risk of cancer, with risk ratios ranging 1,88 to 5,9. There was less consistent evidence linking vitamin B12 and mortality.

HIGHLIGHTS

• Elevated B12 levels exceeding 1000 pg/L, if sustained and unexplainable, warrant a comprehensive individual assessment of each patient. This evaluation should encompass various potential factors contributing to the elevation, aiming to effectively guide the diagnostic process of neoplastic diseases.

• Clinical longitudinal observational studies have suggested a potential link between heightened B12 levels and the risks of cancer and mortality. Nonetheless, these studies have been retrospective cohort studies, and lack a defined threshold point of B12 levels.

• Studies have documented a positive correlation between elevated levels of B12 and the incidence of lung, pancreatic, and liver cancers, as well as certain hematological neoplasms, particularly those related to the myeloid lineage. Conversely, a consistent negative association has been observed in the context of breast cancer. Findings concerning neoplasms of the lower gastrointestinal tract and prostate display contradictory outcomes.

• The diagnostic significance of elevated B12 levels among patients already diagnosed with cancer remains uncertain and could potentially be linked to reverse causality.

Keywords:

• Neoplasms
• cancer risk
• vitamin B 12
• mortality
• systematic review

Acknowledgments

None.

Source of support

None declared by the authors.

Author contributions

Study conception: SBA-G and LM-P.

Conceptualization, methodology and validation: SBA-G, AB-L, LM-P, and JM-C

Data extraction, curation and analysis: SBA-G, LM-P, AB-L, AV-P, MV-B, and JM-C

Writing–Original Draft Preparation: SBA-G, LM-P, AV-P, MV-B, and JM-C

Initial revision of the manuscript: SBA-G, LM-P, AV-P, and MV-B

Critical revision of the manuscript before publication: SBA-G, LM-P, AB-L, and JM-C

All authors have read and approved the submitted manuscript.

Declaration of interest

The authors declare no conflicts of interest. The authors alone are responsible for the content and writing of the article.

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.