Vitamin B12: A secondary analysis of status, biomarkers and other determinants in young and elderly women.

Background/Aim: Vitamin B12 has multiple functions within the human body, including roles as a co-factor for both the one carbon metabolism cycle and methylmalonyl CoA mutase. Vitamin B12 deficiency can have serious lifelong consequences. The aim of this study is to explore the associations between markers of vitamin B12 status and other biochemical, dietary and physical measures. Methods: Three data sets composed of either young omnivore women (n=65; age 24.5 ± 4.4 y; mean ± SD), randomly selected young women (n=305; age 22.5 ± 3.9) and elderly women (n=44; age 80.5 ± 7.6) were examined. Associations between vitamin B12 biomarkers and other selected biomarkers of nutritional status (i.e. serum folate, erythrocyte folate), lifestyle factors such as; dietary intake, alcohol intake, oral contraceptive pill (OCP) use (in the non-elderly groups), and other factors such as BMI were examined using mixed effects regression, accounting for study clusters. Results: Serum vitamin B12 stratification (low, medium or high) was not associated with likelihood of being classed as having a raised methylmalonic acid (MMA) and/or homocysteine (tHcy) (p=0.316). Younger women who used the OCP had serum vitamin B12 concentrations that were 72.3 (SE=12.4) pmol/L lower than non-users (p<0.001), there was however no associations between OCP use and tHcy (p=0.669) or MMA (p=0.595) concentrations. Serum vitamin B12 concentration (pmol/L) was related positively to both serum folate (nmol/L) (β=0.018 95% CI: 0.009, 0.026, p<0.001) and erythrocyte folate (nmol/L) (β =0.456 95% CI: 0.164, 0.747, p<0.01). Vitamin B12 was marginally associated with the intake of protein (p<0.05) and negatively associated with alcohol intake (p