[1] Gilsing, A., Crowe, F., Lloyd-Wright, Z. et al. Serum concentrations of vitamin B12 and folate in British male omnivores, vegetarians and vegans: results from a cross-sectional analysis of the EPIC-Oxford cohort study. Eur J Clin Nutr 64, 933–939 (2010). https://doi.org/10.1038/ejcn.2010.142