Lower Circulating B12 Is Associated with Higher Obesity and Insulin Resistance during Pregnancy in a Non-Diabetic White British Population

Abstract

ObjectiveVitamin B12 and folate are critical micronutrients needed to support the increased metabolic demands of pregnancy. Recent studies from India have suggested that low vitamin B12 and folate concentrations in pregnancy are associated with increased obesity; however differences in diet, antenatal vitamin supplementation, and socioeconomic status may limit the generalisability of these findings. We aimed to explore the cross-sectional relationship of circulating serum vitamin B12 and folate at 28 weeks’ gestation with maternal adiposity and related biochemical markers in a white non diabetic UK obstetric cohort.MethodsAnthropometry and biochemistry data was available on 995 women recruited at 28 weeks gestation to the Exeter Family Study of Childhood Health. Associations between B12 and folate with maternal BMI and other obesity-related biochemical factors (HOMA-R, fasting glucose, triglycerides, HDL and AST) were explored using regression analysis, adjusting for potential confounders (socioeconomic status, vegetarian diet, vitamin supplementation, parity, haemodilution (haematocrit)).ResultsHigher 28 week BMI was associated with lower circulating vitamin B12 (r = -0.25; P<0.001) and folate (r = -0.15; P<0.001). In multiple regression analysis higher 28 week BMI remained an independent predictor of lower circulating B12 (β (95% CI) = -0.59 (-0.74, -0.44) i.e. for every 1% increase in BMI there was a 0.6% decrease in circulating B12). Other markers of adiposity/body fat metabolism (HOMA-R, triglycerides and AST) were also independently associated with circulating B12. In a similar multiple regression AST was the only independent obesity-related marker associated with serum folate (β (95% CI) = 0.16 (0.21, 0.51))ConclusionIn conclusion, our study has replicated the previous Indian findings of associations between lower serum B12 and higher obesity and insulin resistance during pregnancy in a non-diabetic White British population. These findings may have important implications for fetal and maternal health in obese pregnancies.

Prevalence of vitamin B-12 insufficiency during pregnancy and its effect on offspring birth weight: a systematic review and meta-analysis

“…The "Mediterranean diet" contains plenty of fruit, vegetables, and pulses compared with meat (118), which may in part explain this observation because stricter adherence to the diet during pregnancy exacerbated vitamin B-12 deficiency (52). In addition, obesity rates are high in these regions (119), and obesity has been shown to be associated with low vitamin B-12 (79,(120)(121)(122). The link between obesity, gestational diabetes, and low vitamin B-12 concentrations has not been fully explored, but because the former 2 conditions are independently associated with fetal macrosomia, they may partly compensate for or mask the associations between vitamin B-12 and LBW (123,124).…”

Vitamin B12 among Vegetarians: Status, Assessment and Supplementation

“…A depleted status among vegetarian women may be responsible for Cbl deficiency in infants, as well as a failure to thrive, low acceptability of solid foods and delays in neurodevelopment [74]. Moreover, there are indications that an inadequate Cbl status during pregnancy will affect fetal programming mechanisms, resulting in an increase of adiposity and insulin resistance in the offspring at six years, as well as for the mother herself [134,135]. The role of one-carbon metabolism of non-communicable diseases in fetal growth has been discussed [136].…”

Vitamin B12 Status among Pregnant Women in the UK and Its Association with Obesity and Gestational Diabetes

“…Low B12 during pregnancy has implications for materno-fetal health including maternal adiposity, maternal and offspring insulin resistance [12,13,14], and adverse lipid profile in neonates [10,15]. The first two observations were replicated in a cohort of women without GDM from South West England [16] but there are no data available on the role of B12 in GDM in the UK.…”

“…At the other end of the spectrum, maternal obesity and insulin resistance are well-known to be associated with higher fetal birthweight [21,22]. Since B12 may be inversely associated with maternal BMI [12,16], it is possible that B12 is an independent mediator or a confounder for high birthweight.…”