Mean (SD) 4β-OHC in the whole group of patients before and after the intervention was 26 (11) ng/ml and 26 (12). Mean (SD) 4β-OHC:cholesterol ratio in the whole group of patients before and after the intervention was 0.12 (0.046) and 0.13 (0.047). In the Vitamin D group mean (SD) serum 25-OH-vitamin D3 increased from 46 (16) to 85nM (13) during the corresponding time period. To investigate the impact of vitamin D3 on hepatic CYP3A4 we calculated the mean intra-individual differences in 4β-OHC:cholesterol ratio (delta 4β-OHC:cholesterol ratio) before versus after the intervention in the two treatment groups. The difference (95% CI) between delta 4β-OHC:cholesterol ratio in the control group and intervention group was -0.0010 (-0.0093, 0.0072), a difference being not statistically significant (p = 0.80).