Plasma retinol and liver retinyl esters for wild type, heterozygous and homozygous BCMO1-deficient mice. The bar graphs provide the mean ± SD from 4–5 animals/group. Baseline (0 weeks on diet) values are for 6 week-old mice. The β-carotene diet (100 μg β-carotene/g diet) was provided for 4 or 7 weeks starting at 6 weeks-of-age. One-way ANOVA followed by post-hoc analysis (Bonferoni) was performed to determine whether β-carotene diet changes retinoid levels significantly in different tissues for each genotype. *, p<0.05. Black bar, wild type mice (WT); gray bar, heterozygous mice; white bar, homozygous BCMO1-deficient mice (KO).