Interactions among Lp(a) phenotypes, Lp(a) concentrations and lipoprotein response to fat-modified diets

Abstract

Lipoprotein(a) (Lp(a)), an LDL-like particle containing apo(a), a highly glycosylated protein, is a significant genetic risk factor for coronary heart disease (CHD). Lp(a) phenotypes are characterized into single-band and double-band phenotypes according to electrophoretic mobility compared to that of apo B-100. The first goal was to assess whether Lp(a) phenotype influences the concentrations and metabolism of other serum lipoproteins. A second focus was to evaluate the effect on Lp(a) concentrations of substituting medium chain saturated fat for a polyunsaturated, baseline diet. In this two-way cross-over study 18 females are a baseline, polyunsaturated fat diet ( Poly Sat en% ratio = 10.5 11.9 ) for 1 week, and then a high saturated fat diet for 4 weeks ( Poly Sat en% ratio = 3.4 19.8 ) providing either 14 energy % medium chain triglycerides (MCT) 8:0 + 10:0 or 12:0, whereas monounsaturated fat was held constant. Subjects with double-band Lp(a) phenotypes had higher ( P = 0.000) Lp(a) levels on the baseline diet compared to single-band phenotypes. Both diets decreased serum Lp(a) concentration about 30% ( P < 0.05) but raised serum LDL-C about 11%. On the baseline diet, Lp(a) polymorphism did not affect serum LDL-cholesterol levels or receptor-mediated uptake and degradation of LDL. In a two-way ANOVA 8:0 + 10:0 and 12:0 had significantly different effects on change in serum HDL-C concentrations and LDL receptor activity in MNC, but Lp(a) polymorphism had no effect on the variables measured in this study. These results suggest that the response of LDL and Lp(a) levels to the two saturated fat diets were independent of each other. Lp(a) polymorphism did not seem to influence LDL metabolism.