ROLE OF DIETARY-CHOLESTEROL IN THE OPTIMAL DIET FOR THE TREATMENT OF HYPERCHOLESTEROLEMIA

OBJECTIVE: This paper discusses studies in which the effects of dietary cholesterol on the plasma concentrations of lipids and lipoproteins have been evaluated in adult human subjects including patients with hypo- and hypercholesterolemia. DESIGN: The dietary studies were conducted on an outpatient basis in the Clinical Research Center. Each dietary period was four weeks in duration and an adequate washout period was interposed between each dietary phase. SETTING: A university medical centre. PATIENTS: The participants in these studies were adult men or women with hypocholesterolemia, normal volunteers or patients with primary hypercholesterolemia. INTERVENTIONS: The dietary periods consisted of three separate dietary phases in which dietary cholesterol was a single variable. The diets contained 50 mg/day of cholesterol for the low cholesterol diet, 350 mg/day for the moderate cholesterol diet and 650 mg/day for the high cholesterol diet. RESULTS: Concentrations of total and low density lipoprotein (LDL) cholesterol increased in all three patient groups from the low cholesterol to the moderate cholesterol to the high cholesterol diet but the magnitude of increase in LDL cholesterol concentrations was greater in the patients with pre-existent hypercholesterolemia and least in the patients with hypocholesterolemia. in all three patient groups an increased intake of dietary cholesterol was-associated with suppression of endogenous cholesterol biosynthesis as assessed by the urinary excretion of mevalonic acid. CONCLUSIONS: An increased intake of dietary cholesterol results in increases in the plasma concentrations of total and LDL cholesterol in patients with inherently low, normal or high concentrations of LDL cholesterol but the magnitude of increase is greatest in those patients with pre-existent hypercholesterolemia. These results support: the view that restriction of dietary cholesterol leads to a reduction in the plasma concentrations of total and LDL cholesterol and is an appropriate recommendation for patients with known hypercholesterolemia or patients in whom medical recommendations call for a reduction. in the plasma concentrations of total and LDL cholesterol.