U-shape relationship between change in dietary cholesterol absorptionand plasma lipoprotein responsiveness and evidence for extreme interindividualvariation in dietary cholesterol absorption in humans

A possible relationship between change in dietary cholesterol absorptionand plasma lipoprotein responsiveness was examined in 18 normal subjects fed lowfat low cholesterol, high fat low cholesterol, and high fat high cholesteroldiets. For the group, neither dietary cholesterol nor dietary fat affected thepercentage dietary cholesterol absorption, whreas dietary cholesterol intakeraised total and LDL-C and dietary fat raised total, LDL, and HDL-C. On a fixeddiet there was approximately a 2-fold variation among subjects in percentagedietary cholesterol absorption. Subjects also varied in response to dietarycholesterol and fat with regard to dietary cholesterol absorption and plasmalipoprotein responsiveness. There was a U-shaped parabolic relationship betweendietary cholesterol-induced percent change in LDL-C and the change in percentagedietary cholesterol absorption (R2 = 0.62,P = 0.005). A similar but weaker relationship characterizedthe responsiveness of HDL-C (R2 = 0.38,P = 0.05). For the group, increased cholesterol intakeraised dietary cholesterol mass absorption from 1.6 to 4.6 mg/kg per day, butthe range of increase was from 1 to 4.7 mg/kg per day. Increased fat intake alsoaffected dietary cholesterol mass absorption with most subjects displaying astrong inverse relationship between fat intake and mass absorption(r = −0.77, P < 0.003). Insummary: i) the percentage change in dietary cholesterolabsorption in response to dietary cholesterol does appear to regulate dietresponsiveness of LDL and HDL-C, and ii) the large variabilityin percent absorption and changes in percentage and mass absorption in responseto dietary cholesterol suggest the presence of genetically determineddifferences among individuals in the regulation of dietary cholesterolabsorption.—Sehayek, E., C. Nath, T. Heinemann, M. McGee, C. E. Seidman, P.Samuel, and J. L. Breslow. U-shape relationship between change in dietarycholesterol absorption and plasma lipoprotein responsiveness and evidence forextreme interindividual variation in dietary cholesterol absorption in humans.J. Lipid Res. 1998. 39: 2415–2422.