Susanne K. Czarnecki

Influence of Conjugated Linoleic Acid (CLA) on Establishment and Progression of Atherosclerosis in Rabbits

Objective: To determine effects of conjugated linoleic acid (CLA) on establishment and progression of experimentally-induced atherosclerosis in rabbits. Methods: For establishment of atherosclerosis, New Zealand White rabbits were fed a semipurified diet containing 0.1% to 0.2% cholesterol for 90 days. Some groups were fed diet and CLA. For effects on progression of atherosclerosis, rabbits with established atherosclerosis were fed a semipurified diet±CLA for 90 days. Results: At dietary levels as low as 0.1%, CLA inhibited atherogenesis. At dietary levels of 1%, CLA caused substantial (30%) regression of established atherosclerosis. This is the first example of substantial regression of atherosclerosis being caused by diet alone. Conclusion: Dietary CLA is an effective inhibitor of atherogenesis and also causes regression of established atherosclerosis.

Conjugated linoleic acid isomer effects in atherosclerosis: Growth and regression of lesions

Conjugated linoleic acid (CLA), a mixture of positional and geometric isomers of octadecadienoic acid, has been shown to inhibit experimentally induced atherosclerosis in rabbits and also to cause significant regression of pre-established atheromatous lesions in rabbits. The two major CLA isomers (cis9,trans11 and trans10,cis12), now available at 90% purity, have been tested individually for their anti-atherogenic or lesion regression potency. The two major isomers and the mixture were fed for 90 d to rabbits fed 0.2% cholesterol. Atherosclerosis was inhibited significantly by all three preparations. The two CLA isomers and the isomer mix were also fed (1.0%) as part of a cholesterol-free diet for 90 d to rabbits bearing atheromatous lesions produced by feeding an atherogenic diet. A fourth group was maintained on a cholesterol-free diet. On the CLA-free diet atherosclerosis was exacerbated by 35%. Reduction of severity of atheromatous lesions was observed to the same extent in all three CLA-fed groups. The average reduction of severity in the three CLA-fed groups was 26±2% compared with the first control (atherogenic diet) and 46±1% compared with the regression diet. Insofar as individual effects on atherosclerosis were concerned, there was no difference between the CLA mix and the cis9,trans11 and trans10,cis12 isomers. They inhibit atherogenesis by 50% when fed as a component of a semipurified diet containing 0.2% cholesterol; and when fed as part of a cholesterol-free diet, they reduce established lesions by 26%. Reduction of atheromata to the observed extent by dietar means alone is noteworthy.

Influence of graded levels of conjugated linoleic acid (CLA) on experimental atherosclerosis in rabbits

Abstract Dietary CLA inhibits experimental atherosclerosis when fed at a level of 0.1%. In this study rabbits were fed 0.2% cholesterol as part of a semi-purified diet which contained 0, 0.05, 0.075, 0.10 or 0.5% CLA. At levels as low as 0.05% of the diet CLA reduced severity of atherosclerosis in the aortic arch by 20% and in the thoracic aorta by 8%. As dietary concentrations of CLA rose severity of atherosclerosis fell. When the diet contained 0.10% CLA severity of atherosclerosis in the aortic arch and thoracic aorta fell by 40 (p

Cholesterol vehicle in experimental atherosclerosis. 22. Refined, bleached, deodorized (RBD) palm oil, randomized palm oil and red palm oil

The atherogenic effects of refined, bleached and deodorized (RBD) palm oil were compared with those of randomized RBD palm oil and red palm oil. RBD palm oil contains 41.2% palmitic acid, 2.6% at the SN2 position. In randomized palm oil, 13.6% of the palmitic acid is in the SN2 position. Randomized palm oil is significantly more atherogenic for rabbits than is RBD palm oil, supporting our earlier findings that the increasing amounts of palmitic acid in the SN2 position of a fat lead to an increased atherogenic effect. Red palm oil is the oil initially obtained from the palm fruit which contains carotenes and Vitamin E that are removed during refining. Red palm oil was significantly less atherogenic than RBD palm oil supporting the hypothesis that carotenoids and Vitamin E may protect against atherosclerosis. The oils tested had similar effects on serum and liver lipids.

Cholesterol vehicle in experimental atherosclerosis 24: avocado oil.

Objective: To determine atherogenicity of avocado oil relative to saturated (coconut oil), monounsaturated (olive oil) and polyunsaturated (corn oil) fats. Methods: New Zealand White rabbits were fed a semipurified diet containing 0.2% cholesterol and 14% fat for 90 days. They were then necropsied and severity of atherosclerosis was determined visually. Results: Coconut oil was the most atherogenic fat. Corn oil was only slightly less atherogenic than either olive or avocado oils. Percentage of serum HDL cholesterol was highest in the rabbits fed the two monounsaturated fats. Conclusion: Avocado oil is of the same order of atherogenicity as corn oil and olive oil.

Serum and aortic levels of phytosterols in rabbits fed sitosterol or sitostanol ester preparations

Campesterol is present in all the phytosterol-containing dietary hypocholesterolemic agents in current use. Campesterol is absorbed more efficiently than sitosterol, and the question of its possible atherogenicity has been raised. To test this possibility, rabbits were fed either a semipurified, cholesterol-free diet that has been shown to be atherogenic for this species or the same diet augmented with 0.5 g of phytosterol-rich diet preparations (spreads) containing either sitosterol or sitostanol. The diets contained 295 mg phytosterol per 100 g. After 60 d, serum cholesterol levels in the two phytosterol groups were 78±4 mg/dL (sitosterol) and 76±4 mg/dL (sitostanol), respectively. The serum cholesterol level of rabbits fed the control diet was 105±8 mg/dL. Serum campesterol (μg/mL) levels were higher than sitosterol or sitostanol levels in all groups. Aortic phytosterols were present in nanogram quantities compared to cholesterol, which was present in microgram quantities. The ratio of campesterol/sitosterol/sitostanol in the aortas was: control, 1.00∶0.43∶0.02; sitosterol, 1∶00∶0.32∶0.01; sitostanol, 1∶00∶0.34∶0.11. Aortic campesterol was present at 4% the concentration of aortic cholesterol, sitosterol at 1.4%, and sitostanol at 0.14%. Aortic lesions were not present in any of the animals.

Effects of 4-methylsterols from algae and of β sitosterol on cholesterol metabolism in rats

Abstract Male Sprague Dawley rats (8/gp) were fed one of the following diets: AIN-76A (C), C plus 0.5% 4-methylsterols (CM), C plus 0.5% β sitosterol (CS), C plus 0.5% cholesterol (CC), CC plus 0.15% sodium deoxycholate (CB), CB plus 1% 4-methylsterols (CBM) or CB plus 1% β sitosterol (CBS). The 4-methylsterols had no adverse effect on weight gain or organ weight. The 4-methylsterols did not affect serum or liver lipids when added to the control diet or to the cholesterol-bile salt diet. When added to the control diet β sitosterol increased the percentage of serum HDL cholesterol and lowered levels of liver esterified cholesterol. When added to the cholesterol-bile salt diet β sitosterol significantly lowered serum cholesterol and raised HDL-cholesterol levels; β sitosterol also reduced liver total cholesterol.