Vitamin B12 status and metabolic health in women of reproductive age: Population-based biomarker survey

Abstract

Background and aims: In clinical populations, vitamin B₁₂ deficiency has been associated with adverse metabolic health (e.g., gestational diabetes). Population-level data among women of reproductive age could inform screening and interventions. The objective of this analysis was to examine the prevalence of adverse metabolic characteristics (elevated adiposity and central adiposity, hypertension, elevated glycated hemoglobin [HbA1c]) and associations of vitamin B₁₂ status with metabolic characteristics in women as part of a population-based biomarker survey in Southern India.

Methods: Participants (n = 980 women 15-40 y; not pregnant or lactating) were assessed for total vitamin B₁₂, holotranscobalamin, methylmalonic acid, homocysteine, and HbA1c. Categorical anthropometry assessments and bioelectrical impedance analysis (e.g., whole body (WF%) and trunk (TF%) fat) were assessed among adults (≥18 y). Linear and binomial regressions were used to examine associations of vitamin B₁₂ status with metabolic characteristics.

Results: Overall, 25 % of participants had HbA1c ≥5.7 % (HbA1c ≥5.7-<6.5 %: 20.0 %; ≥6.5 %: 5.0 %), and 18.6 % had hypertension (Stage 1: 16.4 %; Stage 2: 2.2 %). Among adults, 23.4 % had body mass index of (BMI) 25.0-<30.0 kg/m², 9.6 % had BMI ≥30.0 kg/m², 13.4 % had elevated waist circumference (WC; >88.9 cm), and 20.8 % had elevated waist-hip ratio (WHR; ≥0.85 cm). Overall, higher vitamin B₁₂ concentrations were associated with lower BMI and WC. Among adults, higher vitamin B₁₂ concentrations were associated with lower WF% and TF%; and lower prevalence of overweight (BMI ≥25.0 kg/m²) and elevated WC, WHR, and WF%. Similarly, vitamin B₁₂ <148 pmol/L was associated with higher BMI and WC overall and, among adults, higher WF% and TF%, and increased overweight (BMI ≥25.0 kg/m²; prevalence ratio: 1.31; 95 % confidence interval: 1.09-1.58), and elevated WC (>88.9 cm; 1.85 [1.32-2.60]), WHR (≥85.0; 1.38 [1.07-1.78]), WF% (>35 %; 1.29 [1.10-1.51]), and TF% (>35 %; 1.25 [1.06-1.49]).

Conclusions: The burden of adverse metabolic characteristics was substantial in this population of young, apparently healthy women. Among those with vitamin B₁₂ <148 pmol/L there was increased central adiposity and overweight status. Evaluating vitamin B₁₂ and metabolic outcomes prospectively could inform screening and interventions to improve women's health.

Registration number: NCT04048330.

Keywords: Body composition; Metabolic health; Overweight; Periconceptional; Vitamin B(12).