Effects of a low fat diet with and without intermittent saturated fat and cholesterol ingestion on plasma lipid, lipoprotein, and apolipoprotein levels in normal volunteers

Diets low in saturated fat and cholesterol are recommended to the American public for improving plasma lipoprotein patterns and reducing the risk of heart disease. However, since dietary intake cannot always be controlled, the effects of different degrees of dietary saturated fat lowering and occasional high saturated fat and cholesterol meals on the expected lipoprotein pattern improvement of these diets needs to be defined. In the current study, we compared lipid, lipoprotein, and apolipoprotein levels in 14 young normal volunteers on a metabolic ward when they were consuming a high saturated fat diet (42% fat), an AHA Phase II diet (25% fat), and a third diet which approximated the AHA Phase I diet (30% fat). The latter actually consisted of intermittent ingestion of meals high in saturated fat and cholesterol on the background of an AHA Phase II diet (Intermittent Saturated Fat diet). When compared to the high saturated fat diet, the AHA Phase II diet significantly reduced total, low density lipoprotein (LDL), and high density lipoprotein (HDL) cholesterol, apoB, and apoA-I levels, and improved the LDL/HDL cholesterol ratio, whereas the intermittent saturated fat diet lowered total and LDL cholesterol and apoB levels, and also improved the LDL/HDL cholesterol ratio. When compared to the AHA Phase II diet, the intermittent saturated fat diet raised total and HDL cholesterol levels. Thus, in these normal volunteers, intermittent saturated fat ingestion, in the context of an overall 30% fat diet and a 25% fat diet, did not differ with respect to the effect on improving the LDL/HDL cholesterol ratio.