The combined indicator of vitamin B12 status calculated using 3-parameters (3cB12) is negatively associated with mortality among US adults: NHANES 1999 to 2004.

The association between vitamin B12 status and the risk of mortality is controversial. The combined indicator calculated using 3 traditional parameters (3cB12) can be used to indicate vitamin B12 status. We hypothesize that vitamin B12 deficiency indicated by 3cB12 may be related to high mortality risks. To evaluate the association between 3cB12 and all-cause, cardiovascular disease (CVD) and cancer-related mortality, we used Cox proportional hazard models, cumulative Kaplan-Meier curves, and smooth curve fitting to assess data from NHANES 1999 to 2004. A total of 12,103 adults (20 years and older) were included in the analyses and 3595 participants were determined as deceased. The median follow-up duration was 202 months. In the fully adjusted model, all three mortality rates decreased along with the increase in 3cB12 scores, with hazard ratio (HR) [95% confidence interval (CI)]: 0.81 (0.75, 0.87) for all-cause mortality, HR (95% CI): 0.83 (0.72, 0.95) for CVD mortality, and HR (95% CI): 0.79 (0.66, 0.96) for cancer-related mortality. When 3cB12 was divided into two groups, individuals in the lower 3cB12 group (3cB12 < -0.5) showed increased risks of all-cause mortality [HR (95% CI): 1.73 (1.48, 2.02)] and CVD mortality [HR (95% CI): 1.84 (1.31, 2.59)], as compared to the higher 3cB12 group (3cB12 ≥ -0.5). The smooth fitting curves represented a negative linear relationship between 3cB12 and all three types of mortality (P for nonlinearity >.05). In conclusion, the extrapolation of 3cB12 from conventional metrics affords a novel perspective for evaluating B12 nutritional status and mortality risk.