Objectives -To compare the long term metabolic effects of two diets for treating hyperlipidaemia.
Design -Randomised controlled study: after three weeks of normal (control) diet, subjects were randomly allocated to one of two test diets and followed up for six months.
Setting -Lipid clinic of tertiary referral centre in Naples.
Subjects -63 subjects with primary type IIa and IIb hyperlipoproteinaemia entered the study, and 44 completed it. Exclusion criteria were taking drugs known to influence lipid metabolism, evidence of cardiovascular disease, homozygous familial hypercholesterolaemia, and body mass index over 30.
Interventions -Two test diets with reduced saturated fat (8%) and cholesterol (-200 mg/day): one was also low in total fat and rich in carbohydrate and fibre, and the other was low in carbohydrate and fibre and rich in polyunsaturated and monounsaturated fats.
Main outcome measures -Fasting plasma lipid and lipoprotein concentrations; blood glucose, insulin, and triglyceride concentrations before and after a test meal.
Results -In comparison with the control diet, both test diets induced significant and similar decreases in low density lipoprotein cholesterol concentrations (by a mean of 0.72 (SE 0.15) mmol/l, P<0.001, for low total fat diet; by 0.49 (0.18) mmol/l, P<0.05, for high unsaturated fat diet) and plasma triglyceride concentrations (by 0.21 (0.09) mmol/l, P<0.05, for low total fat diet; by 0.39 (0.15) mmol/l, P<0.05, for high unsaturated fat diet), while high density lipoprotein cholesterol concentrations after fasting and plasma glucose and insulin concentrations during test meals were not modified by either diet.
Conclusions -Both test diets are suitable (alone or in combination) for treatment of hypercholesterolaemia.