Zurkinden et al. showed that loss of the BA synthesis gene Cyp27a1 in ApoE−/− mice fed a Western-type diet (WD) was associated with an upregulation of Cyp7a1 and cytochrome P450 3A1 (Cyp3a1), resulting in increased BA synthesis and excretion (i.e., accelerated cholesterol turnover), and protection against atherosclerosis [107]. Here, APOE is linked to atherosclerosis.