DIETARY LIPIDS AND BLOOD CHOLESTEROL - QUANTITATIVE METAANALYSIS OF METABOLIC WARD STUDIES

Objective: To determine the quantitative importance of dietary fatty a cids and dietary cholesterol to blood concentrations of total, low den sity lipoprotein, and high density lipoprotein cholesterol. Design: Me ta-analysis of metabolic ward studies of solid food diets in healthy v olunteers. Subjects: 395 dietary experiments (median duration 1 month) among 129 groups of individuals. Results: Isocaloric replacement of s aturated fats by complex carbohydrates for 10% of dietary calories res ulted in blood total cholesterol falling by 0.52 (SE 0.03) mmol/l and low density lipoprotein cholesterol falling by 0.36 (0.05) mmol/l. Iso caloric replacement of complex carbohydrates by polyunsaturated fats f or 5% of dietary calories resulted in total cholesterol falling by a f urther 0.13 (0.02) mmol/l and low density lipoprotein cholesterol fall ing by 0.11 (0.02) mmol/l. Similar replacement of carbohydrates by mon ounsaturated fats produced no significant effect on total or low densi ty lipoprotein cholesterol. Avoiding 200 mg/day dietary cholesterol fu rther decreased blood total cholesterol by 0.13 (0.02) mmol/l and low density lipoprotein cholesterol by 0.10 (0.02) mmol/l. Conclusions:ln typical British diets replacing 60% of saturated fats by other fats an d avoiding 60% of dietary cholesterol would reduce blood total cholest erol by about 0.8 mmol/l (that is, by 10-15%), with four fifths of thi s reduction being in low density lipoprotein cholesterol.