Excess maternal vitamin B12 supplementation increases oxidative stress and differentially influences fatty acids profile in a rat model

Abstract

Vitamin B₁₂ status during pregnancy is an important determinant for non-communicable disease risk in later life. Vitamin B₁₂ and fatty acid are interlinked in one carbon cycle. The effect of vitamin B₁₂ deficiency on adverse pregnancy outcomes and fatty acid status is well known. However, the effects of excess vitamin B₁₂ supplementation during pregnancy are less explored. This study investigates the influence of prenatal excess vitamin B₁₂ supplementation on pregnancy outcome, fatty acids, oxidative stress, inflammation and cardiometabolic variables in Wistar rats. Female rats were divided (pre-pregnancy to pregnancy) into 3 groups as control (0.375 μg/day of vitamin B₁₂), intermediate group (1.5 μg/day) and excess group (120 μg/day). At d20 of gestation, dams were sacrificed to collect blood and placenta for biochemical estimation. We found higher plasma vitamin B₁₂ levels in the intermediate group and excess group (p < 0.01 for both), while folate and homocysteine levels were found to be similar across groups. The pregnancy outcome was similar between groups. We found higher erythrocyte saturated fatty acids, lower omega-6 fatty acids, omega-6/omega-3 fatty acid ratio, and Δ5 desaturase index (p < 0.05 for all) in excess group in comparison with the control group. In comparison with the control group, higher placental Δ6 desaturase index (p < 0.05) and plasma malondialdehyde levels were found (p < 0.01) in excess group. Our study demonstrates that supplementation of excess maternal vitamin B₁₂ during pregnancy leads to increased oxidative stress and differentially influences various fatty acid levels.