Journal Name:
Arteroisclerosis and Thrombosis
Article Title:
Effects of canola, corn, and olive oils on fasting and postprandial plasma lipoproteins in humans as part of a national cholesterol education program step 2 diet
Date Written:
1993
Volume:
13
Number:
Page:
1533
Author(s):
Lichtenstein, A.; Ausman, L.; Carrasco, W.; Jenner, J.; Gualtieri, L.; Goldin, B.; Ordovas, J.; Schaefer, E.
Article:
A number of national health organizations recommend a diet restricted in total fat (<30% calories) and saturated fat (<10% calories) to lower both total and LDL-cholesterol values, which ultimately may reduce the risk of developing coronary heart disease (CHD). It remains unclear whether the remaining fat intake should consist of plant-based oils rich in polyunsaturated (PUFA) or those rich in monounsaturated fat (MUFA). When substituted for saturated fatty acids (SFA), diets very high in PUFA primarily as linoleic acid, have been shown to lower total and LDL-C, but also reduce levels of HDL-C. Additional studies have observed that diets rich in MUFA relative to SFA also lower total - and - LDL-C, with less of a reduction in HDL-C. The purpose of the current study was to investigate the effects of consuming different plant based oils (canola, corn, olive) relatively high in either PUFA or MUFA on plasma lipid profiles in mildly hypercholesterolemic subjects.
Fifteen middle-aged men (n=7) and women (n=8) with LDL-C levels >130mg/dl participated in this randomized double blind study. The study consisted of four 32 day phases with a 1-2 week washout phase between each dietary period. In the first dietary phase (baseline), all participants consumed a diet similar to that characteristic of the United States in order to stabilize plasma lipids. The subjects then randomly assigned one of three experimental diets, all of which were designed to meet the NCEP Step 2 guidelines and provided approximately 15% calories from protein, 55% as carbohydrate, and 30% as fat (<7% saturated). The experimental diets were identical, with the exception that two-thirds of fat intake was derived from canola, corn, or olive oils. Both fasting and postprandial blood samples were collected at baseline, and during the final week of each dietary phase for subsequent analysis of blood lipid profiles.
A reduction in mean plasma cholesterol levels occurred following each of the vegetable oil enriched diets. Reductions were greatest for the corn oil (13%) and canola oil (12%) diets, and significantly less for the olive oil diet (7%). When compared to the baseline phase, LDL-C levels declined by 16%, 17% and 13% for the canola, corn, and olive oil enriched diets, respectively. Mean HDL-C concentrations were 48+/-10 mg/dl during consumption of the baseline diet, and declined to 44+/-10 following the canola oil, 44+/-9 and 46+/-9 mg/dl after the corn and olive oil diets. No significant difference in the total cholesterol to HDL-C ratio among any of the dietary phases was observed. Switching from the baseline to the experimental diets yielded no significant effects on plasma triglycerides, apoA-I, or lipoprotein(a) concentrations. Finally, differences in lipid profiles observed in the fasting state were similar to those observed in the postprandial state.
These results suggest that significant reductions in LDL-C can be achieved in mildly hypercholesterolemic individuals by reducing dietary SFA and cholesterol intake, coupled with the incorporation of vegetable oils rich in either MUFA (canola and olive), or PUFA (corn) as part of an NCEP Step 2 diet. It is important to note that although each vegetable oil produced differential effects on certain plasma lipid measures, no one particular oil had a significant advantage in altering overall lipoprotein profile., , ,
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