APOE and atherosclerosis: Dietary sphingomyelin from egg yolk does not affect circulating sphingomyelin levels or increase atherosclerosis in apoE–/– mice fed a HFD, but it is anti-atherogenic in apoE–/– mice fed a normal chow diet, which may be related to sphingomyelin-mediated alterations in gut flora, a topic that needs further investigation (30).