OBJECTIVETo investigate the effects of a high-carbohydrate diet on the lipid and apolipoprotein ratios in healthy young adults with different genotypes of the polymorphism at -75 site in the promoter region of the gene of apolipoprotein AI (APOA1).

METHODSFifty-six subjects aged (22.89 +/- 1.80) years were given a wash-out diet for 7 days, followed by a high-carbohydrate diet for 6 days. The wash-out diet contained 15% protein, 31% fat, and 54% carbohydrate. The high-carbohydrate diet contained 15% protein, 15% fat, and 70% carbohydrate. Twelve-hour fasting serum lipids and apolipoproteins B100 and AI were measured on the mornings of the 1st, the 8th, and the 14th days from the beginning of the wash-out diet. The ratios of triglyceride (TG)/high-density lipoprotein cholesterol (HDL-C), total cholesterol (TC)/HDL-C, low-density lipoprotein cholesterol (LDL-C)/HDL-C, and apolipoprotein B100 (APOB100)/apolipoprotein AI (APOAI) were calculated. The genome DNA was extracted and the polymorphism of APOA1 -75 G/A was determined by polymerase chain reaction followed by restriction fragment length polymorphism assay.

RESULTSAt baseline, the lipid and apolipoprotein ratios showed no significant differences between the GG genotype and the A carriers in males (P > 0.05), whereas the female A carriers had a significantly higher ratio of LDL-C/ HDL-C compared with the female subjects with the GG genotype (P < 0.05). Following the high-carbohydrate diet, significant decreases of TC/HDL-C were found in all the groups, regardless of sex and genotype (P < 0.01). LDL-C/HDL-C experienced significant decreases in both the genotypes in males (P < 0.05), while in females, significant decrease of LDL-C/HDL-C was only observed in A carriers (P < 0.01).

CONCLUSIONThe A allele of the -75 G/A polymorphism in APOA1 may have specific effects on the LDL-C/HDL-C ratio in females.