Objectives: To analyse the association between the G/A polymorphism in the apolipoprotein A-1 (apo A-1) promoter region and plasma lipid levels, as well as their responses to dietary change, in Finnish adults.
Subjects and design: Blood samples from 86 subjects (42 men. 44 women) who attended a dietary intervention study carried out in North Karelia in 1993 were available for the current analysis. The diet study consisted of a 2-week baseline period, followed by an 8-week intervention period, and an 8-week switchback period.
Intervention: Diet was modified to a low-fat, low-cholesterol diet during the dietary intervention.
Main outcome measures: Fasting plasma lipid, lipoprotein and apoliprotein levels were determined.
Results: At baseline, the high-density lipoprotein (HDL) cholesterol and apo A-1 levels were higher (P < 0.01) and the triglyceride levels were lower (P < 0.05) in men, but not in women, with the A allele. The differences in HDL cholesterol and apo A-1 levels between genotypes remained during the lowfat, low-cholesterol diet and switchback periods. Apart from the difference between responses in apo A-1 during switchback to the original diet, lipid responses to dietary change did not differ significantly between genotypes.
Conclusion: Our findings indicate a significant association between the apo A-1 promoter polymorphism and plasma apo A-1 and HDL-cholesterol in men. In theory, the higher plasma HDL-cholesterol and apo A-1 levels in the GA/AA group may confer some protection against coronary artery disease. The differences in HDL-cholesterol and apo A-1 levels between genotypes persisted during different diets suggesting that the possible benefit is independent of fat and cholesterol intake.