Vitamin B₁₂ Supplementation and Vitamin B₁₂ Blood Serum Levels: Evaluation of Effect Modification by Gender and Smoking Status

Abstract

Research suggests that high intake of supplemental vitamin B₁₂ may be associated with increased risk of cancer, with some evidence that this association may vary by gender and smoking status. This investigation evaluates if similar patterns in association are observed for data for 11,757 adults from the National Health and Nutrition Examination Survey (1999-2006). Survey-weighted multivariable-adjusted linear regression was used to evaluate the association between regular B₁₂ supplement use and log-transformed serum B₁₂ levels. Persons taking vitamin B₁₂ through a multivitamin/multimineral (MVMM) had a median supplemental intake of 12 mcg/day (Q1: 6, Q3: 25), compared to 100 mcg/day (Q1: 22, Q3: 500) for persons reporting supplemental B₁₂ intake through a MVMM-exclusive source. MVMM users had a geometric mean serum B12 26% (95% CI: 23%-30%) higher than nonusers, whereas MVMM-exclusive users’ geometric mean was 61% (95% CI: 53%-70%) higher than nonusers (p-trend < 0.001). Although a positive trend (p-trend < 0.001) was observed for both men and women, the association was stronger among women (p-interaction < 0.001). No interaction was observed for smoking status (p-interaction = 0.45). B₁₂ supplementation is associated with higher levels of serum B₁₂, with significant interaction by gender but not smoking. Further work is needed to better understand the interplay of B₁₂ and gender.

Acknowledgments

We thank the Memorial Sloan Kettering Quantitative Science Undergraduate Research Experience, an NCI-funded training grant (R25 CA214255).

Declaration of Interest Statement

Authors have no conflict of interest to report.

Authors’ Contributions

HEF and EDK designed the study, with additional consultation from KO, MD, SLN, and TMB. HEF and KO conducted the statistical analyses. KO managed the database. HEF, EDK, KO, MD, SLN, and TMB aided in interpreting results. HEF and EDK drafted the manuscript in consultation, with edits provided by KO, MD, SLN, and TMB.

Additional information

Funding

This work was supported by the National Cancer Institute of the National Institutes of Health under Grant R25 CA214255 and P30 CA008748.