Objective: To evaluate the efficacy of a limited dietary intervention delivered by dietitians in a single counseling session on plasma lipid levels in free-living subjects with hyperlipidemia.

Methods: A 2-month, nonrandomized comparative study of dietary counseling efficacy in subjects with hyperlipidemia. Dietary instruction was conducted in a lipid clinic by dietitians. Subjects were instructed to follow a diet low in saturated fat and cholesterol (National Education Cholesterol Program step 1 or 2 diets) for 2 months with concomitant energy restriction for weight reduction when necessary. Another group of patients who did not receive dietary counseling during the same period served as a control. Methods: Ambulatory patients were recruited from the Lipid Clinic of the Montreal Clinical Research Institute. Methods: Dietary counseling was provided to 104 subjects with hypercholesterolemia and 113 subjects with hypertriglyceridemia. They were compared with 72 subjects with hypercholesterolemia and 80 subjects with hypertriglyceridemia who did not receive dietary counseling.

Results: In the hypercholesterolemic group, significant reductions in plasma cholesterol (mean +/- standard deviation = -5.7 +/- 11.7%) and low-density lipoprotein cholesterol (LDL-C) (-7.3 +/- 14.2%) and no changes in plasma very-low-density lipoprotein cholesterol (VLDL-C) or high-density lipoprotein cholesterol (HDL-C) were observed after dietary counseling. The LDL-C response to diet was normally distributed, and 20% of the individuals with hypercholesterolemia reached LDL-C levels below 4.1 mmol/L. In patients with hypercholesterolemia and no clinical evidence of familial hypercholesterolemia, (n = 76) the reductions in plasma cholesterol (-6.6 +/- 10.8%) and LDL-C (-8.2 +/- 14%) were more pronounced. Among the latter patients, 27.6% reached LDL-C levels below 4.1 mmol/L. In subjects with hypertriglyceridemia, the reductions in plasma cholesterol (-4.8 +/- 12.8%), triglycerides (-20.7 +/- 33%), and VLDL-C (-19.5 +/- 29%) were associated with an increase in LDL-C (+8.5 +/- 25.7%) and HDL-C (+5.5 +/- 18%). Of the subjects with hypertriglyceridemia, 20% had triglyceride levels below 2.3 mmol/L after treatment. No significant changes were observed in the control groups during the same period.

Conclusions: Dietary counseling of subjects with hypercholesterolemia or hypertriglyceridemia was associated with beneficial changes in plasma lipid levels after 2 months of dietary intervention. However, longer and more controlled dietary interventions are necessary for most patients to achieve lipid goals.