DOES A DIET HIGH IN CORN-OIL LOWER LDL CHOLESTEROL LEVELS IN WOMEN VIA AN EFFECT ON LDL RECEPTOR ACTIVITY

To determine if a high intake of corn oil alters LDL receptor activity , a model emphasizing freshly isolated mononuclear cells (MNC) was use d with 12 women consuming 40 energy% fat diets based on corn oil or bu tter in a randomized crossover design. Each phase included 1 week of a prescribed but selfselected high saturated fat (SFA) diet at home fol lowed by 4 weeks of a designated fat-based diet consumed in a metaboli c kitchen. There was a 7-week washout period between phases. LDL degra dation through and binding to LDL receptors were 63 and 100% higher, r espectively, on the corn oil diet than the butter diet (P < 0.05). Cha nges in LDL receptor activity and serum LDL cholesterol concentration were moderately associated (r = -0.4 to -0.6). Compared with the butte r group, total unsaturated and saturated fatty acid contents of MNC we re 166% higher and 150% lower, respectively, in the corn oil group. Ch anges in saturated and unsaturated fatty acids and receptor-mediated L DL degradation were associated (r = -0.6 and 0.6, respectively). These findings suggest that the change in fatty acid composition in MNC may enhance the LDL receptor-mediated pathway. Receptor-mediated LDL degr adation may account for only part of the effect of corn oil on serum L DL cholesterol concentrations in healthy women.