Effects of dietary monounsaturated fatty acids on lipoprotein concentrations, compositions, and subfraction distributions and on VLDL apolipoprotein B kinetics: dose-dependent effects on LDL.
BACKGROUND
Replacing dietary saturated fatty acids (SFAs) with monounsaturated fatty acids (MUFAs) lowers LDL cholesterol, but the underlying mechanisms remain unclear.


OBJECTIVE
We assessed the effects of replacing dietary SFAs with MUFAs on concentrations and subclass distributions of VLDL, intermediate-density lipoprotein, LDL, and HDL and on VLDL apolipoprotein B kinetics.


METHODS
Thirty-five moderately hypercholesterolemic, middle-aged volunteers consumed for 6 wk, in random order, diets containing low (L-MUFA; 7.8% of energy from MUFAs), moderate (M-MUFA; 10.3% from MUFAs), or high (H-MUFA; 13.7% from MUFAs) amounts of MUFAs. Fasting blood samples were taken from all subjects after each intervention. VLDL apolipoprotein B kinetic studies were performed in a subgroup after the L-MUFA and H-MUFA diets.


RESULTS
Plasma cholesterol concentrations decreased in a dose-dependent manner with increasing intakes of dietary MUFAs. This change was entirely accounted for by reduced LDL cholesterol (-0.20 and -0.49 mmol/L after the M-MUFA and H-MUFA diets, respectively, compared with the concentration after the L-MUFA diet; P for trend < 0.01). Plasma triacylglycerol and HDL cholesterol were not significantly affected by the dietary intervention, nor were the concentrations of VLDL(1) (S(f) 60-400), VLDL(2) (S(f) 20-60), or intermediate-density lipoprotein (S(f) 12-20). Production and catabolic rates for VLDL(1) and VLDL(2) were also unaffected. HDL and LDL subclass distributions were not significantly altered, but as a consequence of the overall LDL lowering, concentrations of atherogenic LDL-III were 25% lower after the H-MUFA diet than after the L-MUFA diet (P = 0.02).


CONCLUSIONS
The effects of replacing dietary SFAs with MUFAs on lipoprotein metabolism appear to be almost exclusively limited to the LDL density class.
Gill
Jason M R
JM
Department of Pathological Biochemistry, University of Glasgow, Glasgow, United Kingdom . j.gill@bio.gla.ac.uk
Brown
Jacqueline C
JC
Caslake
Muriel J
MJ
Wright
Dawn M
DM
Cooney
Josephine
J
Bedford
Dorothy
D
Hughes
David A
DA
Stanley
John C
JC
Packard
Chris J
CJ
D001053:Apolipoproteins / Q000097:blood; D001055:Apolipoproteins B / Q000097:blood*; D004032:Diet; D004305:Dose-Response Relationship, Drug; D005215:Fasting / Q000097:blood; D005229:Fatty Acids, Monounsaturated / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D007700:Kinetics; D008055:Lipids / Q000097:blood; D008074:Lipoproteins / Q000097:blood*; D008077:Lipoproteins, LDL / Q000097:blood; D008079:Lipoproteins, VLDL / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration
D001053:Apolipoproteins; D001055:Apolipoproteins B; D005229:Fatty Acids, Monounsaturated; D008055:Lipids; D008074:Lipoproteins; D008077:Lipoproteins, LDL; D008079:Lipoproteins, VLDL