[Combined effect of saturated fat and cholesterol intake on serum lipids of urban tehranians: tehran lipid and glucose study [TLGS]]

ABSTRACT

Despite many studies on the effect of saturated fat and cholesterol intake on serum lipids, data on the combined effect of these two dietary components on serum lipoprotein response is very limited. In this study, a representative sample of 443 subjects, aged 18 years and over, were included. Dietary intake was assessed by means of two 24-hour dietary recall questionnaires. Height and weight were measured and BMI was calculated. Total cholesterol, triglycerides and high density lipoprotein cholesterol levels were measured and serum cholesterol was calculated. Cholesterol intake 2300 mg/day was defined as high cholesterol intake, and saturated fat intake 37% of total energy was defined as high saturated fat intake. Individuals were categorized into 4 groups, based on cholesterol and saturated fat intake; each of these was assessed for 2 levels of serum lipids, normal and high. Pearson's correlation coefficient was used to detect confounding variables. Two-Way ANOVA was used to determine both the main effect of each of the two factors on lipids and their combined effect as well. Mean age of subjects was 40.1 +/- 14.6 y. The main effect of cholesterol and saturated fat intake on energy intake was significant. Subjects in whom cholesterol and saturated fat intake was normal had significantly less energy and fat intake than those who had high cholesterol and saturated fat intake [p<0.01]. Saturated fat intake was seen to have a significant main effect on serum total and HDL cholesterol levels. Subjects who had a normal saturated fat intake, had significantly less serum total and HDL cholesterol than those who had high saturated fat intake [p<0.01 and p<0.05, respectively]. Adjusted for age, sex and BMI, the main effect of cholesterol intake on HDL cholesterol was significant [p=0.05]. Mean serum HDL was lower in subjects who had normal cholesterol intake than in subjects who had high cholesterol intake. The present study shows that cholesterol and saturated fat intake had no combined effect on serum LDL cholesterol level, whereas cholesterol intake per se did affect serum HDL cholesterol level