No abstract

We compared the cardiovascular risk-reduction potential of three major polyunsaturated fatty acids in a double-blind study. Thirty-three normotensive and mildly hypercholesterolemic men were randomly allocated to one of three diets supplemented with linoleic acid (14.3 g/d), alpha-linolenic acid (9.2 g/d), or eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA) (3.4 g/d). Diets were matched to provide similar amounts of the major classes of fatty acids and cholesterol. Blood pressure and plasma lipids were measured for 6 wk after a 3-wk run-in period on the linoleic acid supplement. For the diet supplemented with EPA plus DHA compared with the linoleic acid diet systolic blood pressure fell 5.1 mm Hg (p = 0.01); plasma triglyceride and VLDL cholesterol fell by 39% (p = 0.001) and 49% (p = 0.01), respectively; and LDL cholesterol rose by 9% (p = 0.01). There were no significant changes with the diet supplemented with alpha-linolenic acid. The net effect on cardiovascular risk therefore is complex and the systolic blood pressure reduction was substantial.

Low-density lipoprotein (LDL) oxidation was measured in vitro to determine intraindividual variability and to relate oxidation to linoleic acid enrichment. Intraindividual variability was determined for eight subjects on 3 consecutive days after 14 d on a fixed diet. Coefficients of variation were 7.49 +/- 1.50%, 6.58 +/- 1.16%, and 4.58 +/- 0.77% for oxidation rate, lag time, and diene concentration, respectively. In the second study 12 normolipidemic men consumed a daily diet supplement containing 35 g linoleate-rich oil in one period and 35 g oleate-rich oil in the other period (2 x 3 wk crossover). LDL oxidized faster after the linoleate diet than after the oleate diet (mean +/- SE: 16.42 +/- 0.85 and 13.16 +/- 0.68 nmol diene.mg LDL protein-1.min-1, respectively, P < 0.02) and produced more conjugated diene (416 +/- 12.60 and 379.29 +/- 11.06 nmol/mg protein, respectively, P < 0.05) in proportion to the increase in LDL linoleate (r = 0.698, P < 0.001 and r = 0.618, P < 0.01 for rate and diene concentration, respectively). Lag time before onset of oxidation was not significantly altered by the linoleate-rich diet.

The aim was to establish whether interesterification of oils, an alternative to the use of trans fatty acids in margarine manufacture, adversely affects plasma lipids. Twenty-seven hypercholesterolemic men participated in a double-blind, crossover trial of three margarines: 1) high-linoleic acid, moderate trans fatty acids; 2) high-palm oil blend (predominantly lauric, myristic, palmitic, oleic, and linoleic acids); and 3) an interesterified form of the high-palm oil margarine. Both high-palm oil margarines led to similar low-density-lipoprotein (LDL) cholesterol concentrations (4.43 +/- 0.94 and 4.54 +/- 0.88 mmol/L, respectively), which were significantly higher than the LDL concentrations after the high-linoleic acid margarine (4.02 +/- 0.85 mmol/L, P < 0.001). Interesterification transferred substantial proportions of palmitic acid into the sn-2 position of glycerides and unsaturated fatty acids into the sn-1,3 positions, and this was reflected in plasma chylomicrons. This study shows that interesterification of oils used to harden margarines does not raise plasma cholesterol more than does the margarine's constituent fatty acids.

The effects of fish and fish oil on lipids, hemostasis, and blood pressure were compared in 25 mildly hyperlipidemic men who received 4.5 g eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA) daily for 5 wk. Six additional subjects served as controls. Fish and fish oil lowered plasma triglycerides 20% and 28% and very-low-density-lipoprotein (VLDL) triglycerides 42% and 52%, respectively (all P less than 0.05 compared with control). High-density-lipoprotein (HDL) cholesterol increased by 10% and 9%, with 34% and 32% increases in the proportion of HDL2 particles for fish and fish oil, respectively. Changes in total cholesterol, LDL cholesterol, apolipoprotein B, and blood pressure with fish and fish oil were not significantly different from changes for the control diet. The fish lowered fibrinogen (15.7%) and thromboxane (10.5%) and increased bleeding time (10.8%) (P less than 0.05 compared with control). Eating fatty fish and fish oil produced comparable lipid and lipoprotein changes, but only the fish improved hemostatic factors.