RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM OF THE APOLIPOPROTEIN-B GENEAND RESPONSE TO DIETARY-FAT AND CHOLESTEROL

OBJECTIVE: The relationship between response to dietary fat and choles terol, and the EcoRI restriction fragment length polymorphism (RFLP) o f the apolipoprotein B(apoB) gene was examined. DESIGN: Forty-nine fre e-living subjects took part in a prospective double-blind crossover di etary intervention study. The apoB EcoR1 cutting site was present in f ive women and 18 men (E+) and absent in 15 women and 11 men (E-). INTE RVENTION: Subjects consumed a low fat (25%energy), low cholesterol (le ss than 200 mg/day) diet. After two weeks on this background diet (bas eline) subjects were randomly assigned to consume a liquid supplement for three weeks which was either fat and cholesterol free or which con tained fat (30 to 36 g) and cholesterol (650 to 780 mg). After the fir st three-week period subjects switched to the other supplement. Blood samples were collected for plasma lipid analysis after an overnight fa st on two consecutive days at the end of baseline and on three consecu tive days after each three-week supplement period. RESULTS: There was no significant difference in response to diet between the RFLP groups. Changes in plasma total, low density lipoprotein (LDL), high density lipoprotein (HDL), HDL(2) and HDL(3) cholesterol or plasma triglycerid e were not different between the two RFLP groups. There was a signific ant difference between RFLP groups for baseline HDL(2)-cholesterol (0. 31+/-0.04 and 0.16+/-0.02 mmol/L for E- and E+ subjects, respectively) which was independent of sex and apoE genotype (P=0.032). CONCLUSIONS : These results indicate that the EcoRI RFLP of the apoB gene is not a ssociated with response to dietary fat and cholesterol.