ABSTRACT

Background While studies have examined the associations between folate, vitamin B12, and cardiovascular mortality in high-risk populations, evidence regarding these associations in non-diabetic population remains limited. This study aimed to assess the associations of serum folate and vitamin B12 levels with cardiovascular mortality in a large, nationally representative cohort of US non-diabetic adults.

Methods and Results Data were extracted from the National Health and Nutrition Examination Survey (NHANES) cycles from 1999 to 2006 and 2011 to 2014. Multivariate logistic regression and restricted cubic spline (RCS) analyses were used to evaluate the associations between serum folate, vitamin B12 and cardiovascular mortality. A two-piecewise logistic regression model was employed to identify the inflection points of serum folate and vitamin B12 levels on cardiovascular mortality. Among 19,402 US adults, the mean age was 43.9 ± 18.6 years, 9,749 (50.2%) were male, and 8,438 (43.5%) were non-Hispanic White. With a median follow-up of 159 months (IQR: 82.0-193.0 months), 928 cardiovascular deaths were documented. After fully adjusting for potential confounders, a significant inverse association was observed between serum folate levels and cardiovascular mortality. The RCS analysis revealed non-linear associations between serum folate (P for nonlinearity = 0.02), vitamin B12 levels (P for nonlinearity = 0.04), and the risk of cardiovascular mortality. Specifically, serum folate levels below 19.50 ng/mL and serum vitamin B12 levels at or above 436.52 pg/mL were both linked to an increased risk of cardiovascular mortality. Stratified and sensitivity analyses confirmed the robustness of these associations.

Conclusions This study demonstrated that low serum folate levels and high vitamin B12 levels were associated with an increased risk of cardiovascular mortality in non-diabetic individuals. These findings provide evidence supporting the potential of serum folate and vitamin B12 levels as biomarkers for cardiovascular mortality risk estimation, pending further validation in other independent cohorts.

Competing Interest Statement

The authors have declared no competing interest.

Clinical Trial

This study is based on secondary data analysis using the publicly available National Health and Nutrition Examination Survey (NHANES) database. NHANES is not a clinical trial, and as such, it does not require registration in a clinical trial registry. Therefore, this study does not have a trial ID. The research is purely observational and focused on exploring associations within existing publicly available data.

Funding Statement

Supported by Key Specialty Construction Project of Shanghai Pudong New Area Health Commission (Grant No. PWZzk2022-03) and Top-level Clinical Discipline Project of Shanghai Pudong District (Grant No. PWYgf 2021-01). The funders had no role in the study design, data analysis, decision to publish, or preparation of the manuscript.

Author Declarations

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The National Health and Nutrition Examination Survey (NHANES) has been approved by the National Center for Health Statistics Ethics Review Board, and all participants provided informed written consent at enrollment.

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes

Data Availability

The datasets used during the current study are available from the corresponding author on reasonable request.

Nonstandard Abbreviations and AcronymsHEI-2015healthy eating index-2015HHcyhyperhomocysteinemiaRCSrestricted cubic spline