The effect of apolipoprotein B xbal polymorphism on plasma lipid response to dietary fat

Background and aims Lipid response to dietary fat and cholesterol is, to a large extent, genetically controlled. Apolipoprotein B (apo B) plays a domi nant role in cholesterol homeostasis. Several polymorphic sites within or a djacent to the gene locus for apo B have been detected. The X+ allele of th e XbaI restriction fragment polymorphism of the apo B gene has been found t o be associated with higher serum cholesterol and/or triglyceride levels. I n order to study the influence of this mutation on the plasma lipid respons e in diets of varying fat content, 72 healthy male subjects were studied, 2 1 X- X- (X-) and 51 X+ (X+ X- or X+ X+). Methods and results These subjects followed three consecutive 28-day diet p eriods: one rich in saturated fats (SAT diet; 38% fat, 20% saturated); a Na tional Cholesterol Education Program type I diet (NCEP-I diet) (28% fats, < 10% saturated); and a third monounsaturated (MUFA diet)(38% fats, 22% monou nsaturated). The different genotypes can be observed to have significant ef fects on total and LDL cholesterol concentrations (P < 0.017). X+ individua ls had higher levels of total and LDL cholesterol after the consumption of a SAT diet (P < 0.012; P < 0.006, respectively), NCEP diet (P < 0.060; P < 0.054, respectively) and MUFA. diet (P < 0.022; P < 0.042, respectively) in comparison with X- individuals. A significant interaction between genotype s and dietary effects was observed for diet-induced changes in plasma trigl ycerides (P < 0.032). Significant decreases in the absolute values of trigl yceride concentrations (-0.18 mmol L-1, P < 0.024) were noted in the X- sub jects after the high intake of a MUFA diet, while no significant difference s were observed in the X+ individuals (0.006 mmol L-1, P < 0.858). Conclusions Our results suggest that the total triglyceride response to die t is influenced by the apo B XbaI polymorphism.