Vitamin B12 Status and Metabolic Health in Women of Reproductive Age in Southern India

Abstract

ObjectivesTo examine the burden of metabolic outcomes and associations of vitamin B12 status with metabolic health in women of reproductive age (WRA), as part of a population-based biomarker survey in Chittoor, India. MethodsParticipants (980 WRA; 15–40y nonpregnant or lactating) were assessed for glycated hemoglobin (HbA1c; nephelometry) and serum vitamin B12 concentrations (chemiluminescence). Anthropometric measurements and systolic (SBP) and diastolic (DBP) blood pressures were collected in triplicate. Bioelectrical impedance analysis was used to evaluate whole body (WF%) and trunk (TF%) fat among women ≤ 18y. We defined elevated HbA1c as ≤ 6.5% and ≤ 5.7-< 6.5%, and hypertension as stage 1 (SBP 130–139 or DBP 80–89 mmHg) and stage 2 (SBP ≤ 140 or DBP ≤ 90 mmHg). Vitamin B12 was natural logarithmically transformed prior to analyses; vitamin B12 deficiency was defined as < 148 pmol/L. Linear and binomial regression models were used to examine associations of vitamin B12 status with metabolic outcomes. ResultsA total of 23.3% of adult WRA were overweight (body mass index (BMI): 25.0 to < 30.0 kg/m2) and 9.7% had obesity (≤30.0 kg/m2). Waist circumference (WC; ≤88.9 cm) and waist-hip ratio (WHR; ≤0.85) were elevated in 13.4% and 20.1% of adult WRA. One-fourth of WRA had elevated HbA1c (≤6.5%: 5.0%; ≤5.7-< 6.5%: 20.0%), and 18.6% had hypertension (stage 1: 16.4%; stage 2: 2.2%); 48.3% of WRA were vitamin B12 deficient. Higher continuous vitamin B12 concentrations were associated with lower BMI (β [standard error (SE)] -0.65 [0.28]) and WF% (-1.01 [0.50]); lower risk of elevated WC (risk ratio (RR) [95% confidence interval] 0.64 [0.49–0.85]); and higher risk of HbA1c ≤ 5.7% (1.19 [1.00–1.41]). Vitamin B12 deficiency was associated with higher BMI (β [SE] 0.98 [0.34], p = 0.004), WC (1.96 [0.76]), WF% (1.75 [0.59]), and TF% (2.03 [0.73]); and higher risk of having overweight (RR: 1.31 [1.09–1.58]), elevated WC (1.85 [1.32–2.60]), and WHR (1.38 [1.07–1.78]). ConclusionsThe burden of adverse metabolic outcomes was substantial in this population, and vitamin B12 deficiency was associated with central adiposity and overweight. Evaluating the role of vitamin B12 in the development of metabolic outcomes in future studies could inform screening and interventions to improve vitamin B12 status and metabolic health in WRA. Funding SourcesCenters for Disease Control and Prevention.