Fig. 2

Association between observed serum folate concentrations and values predicted by the respective linear mixed-effects model. This figure illustrates the model fits of models 2, 3 and 4 as well as the model fit of the restricted model 4 applied in sensitivity analysis. Model fit was 0.620, 0.668, 0.552 and 0.834, respectively. a Model 2 with serum folate as dependent variable and fixed effects for serum cobalamin, vitamin B/multi-vitamin supplementation, age, absolute fat-free mass, cobalamin intake, folate intake, alcohol intake, smoking, sex and effect modifications by sex and age (n = 332); b Model 3 based on model 2 but is restricted to subjects with creatinine measurements and included serum creatinine as additional fixed effect (n = 202); c Model 4 based on model 3 but excluded records with use of vitamin B/multi-vitamin supplements (n = 161); and (d) Model 4 without subjects with lifetime diagnosis of cancer/inflammatory bowel disease and records with serum cobalamin > 1000 pmol/L or residuals outside of the assumed normal distribution (n = 122); serum folate concentrations were logarithmically transformed for normalization purposes