Research articleDifferent palm oil preparations reduce plasma cholesterol concentrations and aortic cholesterol accumulation compared to coconut oil in hypercholesterolemic hamsters☆
Introduction
The oil obtained initially upon harvesting the fruit of the oil palm is red due to its content of carotene, tocopherol and tocotrienols. The palm oil generally available for use (refined, bleached and deodorized or RBD-PO) has been processed to remove the carotene and tocopherols. This fractionation brings about an increase in monounsaturated oleic acid with the concomittant reduction of palmitic acid, the major saturated fatty acid [1], [2]. Palm oil contains a higher proportion of palmitic acid as well as considerable quantities of oleic and linoleic acids, which give it a higher unsaturated fatty acid content than coconut oil and palm kernel oil [3], [4], [5], [6]. Throughout the world, 90% of palm oil is used for edible purposes (e.g., margarine, deep fat frying, shortening, ice creams, cocoa butter substitutes in chocolate) [7], [8].
Red palm oil (RPO) contains 50% saturated, 40% monounsaturated and 10% polyunsaturated fatty acids [9]. Red palm oil is the richest food source of carotenoids (500–750 mg/L) [4] and a very good source of vitamin E (tocopherols and tocotrienols) (560–100 ppm) [2], [10], [11]. The carotenoids, together with tocopherols and tocotrienols, ascorbic acid, enzymes and proteins, are members of the biological antioxidant network [12], [13] converting highly reactive radicals and free peroxy radicals to less active species, thus protecting against oxidative damage to cells [14].
Previous work has shown that tocopherol and tocotrienols may be anti-atherogenic, although they may have no effect on plasma cholesterol concentrations. Tocopherols have been reported to inhibit atherosclerosis in rabbits [15], [16] and in monkeys [17]. Antioxidants have been shown to reduce the risk of atherosclerosis in human populations [18], [19]. Tocotrienols have been reported to be natural inhibitors of cholesterol synthesis [20], [21]. The tocopherols and tocotrienols promote an antithrombotic state by reducing platelet aggregation and modulating prostanoid synthesis [21], [22], [23], [24]. Based on this information, one might then expect RPO to be less atherogenic than RBD-PO. Kritchevsky et al. [25] have shown this to be the case in studies of experimental atherosclerosis in rabbits. To further investigate the role that the carotenoids and tocopherols of RPO may play in its comparative protective action, Kritchevsky et al. [26] have compared atherogenicity in cholesterol-fed (0.1%) rabbits of RPO, RBD-PO and RBD-PO to which the antioxidant components of RPO have been added (reconstituted RPO). RBD-PO was shown to be 58% more atherogenic than RPO and 13% more atherogenic than the reconstituted RBO.
In this manuscript, we describe the atherogenic effects of RPO, RBD-PO and reconstituted RBD-PO when substituted for coconut oil in the hamster model, which has been previously described [27].
Section snippets
Animals and experimental design
Forty-eight F.B. Golden Syrian hamsters (Mesocricetus auratus) (BioBreeders, Watertown, MA) were used. They were group housed (three/cage) in hanging polystyrene cages with bedding in a temperature-controlled room (25°C) maintained on a 12-h light/dark cycle. Hamsters were given food and water ad libitum. Hamsters were fed Purina Hamster Chow (Ralston Purina, St. Louis, MO) for 1 week in order to acclimate them to the facility. The hamsters were then fed a nonpurified hypercholesterolemic diet
Results
All hamsters in each group survived the entire length of the study. No significant differences were observed between dietary treatments for initial body weight; however, by the end of the 10-week treatment period, the hamsters fed the coconut oil diet and the 50:50 mixture oil diet had gained 10% more body weight than the hamsters fed the RBD-PO (P<.05) (data not shown). At the same time, no significant difference for food consumption between the treatment diets was observed (data not shown).
Discussion
Palm oil has been stigmatized as a hypercholesterolemic fat because of its palmitic acid (16:0) content. In this study, coconut oil was the most hyperlipidemic of the test fats. Red palm oil was somewhat less cholesterolemic (10–20%) than either RBD-PO or the reconstituted RBD-PO resulting in a lower total to HDL-cholesterol ratio. Plasma triglyceride concentrations in hamsters fed RPO were almost as high as those in hamsters fed coconut oil and about 33% higher than in hamsters fed either
Acknowledgment
The palm oil preparations were a gift of the Malaysian Palm Oil Board, Kuala Lumpur, Malaysia. The authors would like to thank Monica McIntyre, Julie Desjardins, Anthony DeSimone, Catherine Jones and Ben Woolfrey for their technical assistance, and Maureen Faul for her administrative assistance.
References (51)
Nutritional aspects of palm oil
Am J Clin Nutr
(1991)- et al.
Coconut oil and sesame oil affect lymphatic absorption of cholesterol and fatty acids in rats
J Nutr
(1993) - et al.
Dietary fatty acid profile influences the composition of skeletal muscle phospholipids in rats
J Nutr
(1996) - et al.
Defining food components as new nutrients
J Nutr
(1994) - et al.
Vitamin E, antioxidants and lipid peroxidation in experimental atherosclerosis in rabbits
J Nutr
(1978) - et al.
Inverse correlation between plasma vitamin E and mortality from ischemic heart disease in cross cultural epidemiology
Am J Clin Nutr
(1991) - et al.
Lowering of serum cholesterol in hypercholesterolemic humans by tocotrienols (palm vitee)
Am J Clin Nutr
(1991) - et al.
Decreased prostacyclin synthesis in vitamin E deficient rabbit aorta
Am J Clin Nutr
(1981) - et al.
Cholesterol vehicle in experimental atherosclerosis: 22. Refined, bleached, deodorized (RBD) palm oil, randomized palm oil and red palm oil
Nutr Res
(2000) - et al.
The hypercholesterolemic effect of soybean protein vs. casein in hamsters fed cholesterol-free or cholesterol enriched semipurified diets
J Nutr
(1991)
Effect of the ACAT inhibitor CI-976 on plasma cholesterol concentrations and distribution in hamsters fed zero- and no-cholesterol diets
Clin Biochem
The reevaluation of the ferric thiocyanate assay for lipid hydroperoxides with special considerations of the mechanistic aspects of the response
Free Radic Biol Med
Studies of cholesterol and bile acid metabolism in hamsters fed GT16-239, a novel bile acid sequestrant (BAS)
Atherosclerosis
A simple method for the isolation and purification of total lipids from animal tissue
J Biol Chem
Nonhypercholesterolemic effects of a palm oil diet in Malaysian volunteers
Am J Clin Nutr
Cholesterol vehicle in experimental atherosclerosis. Cottenseed oil and randomized cottonseed oil
Nutr Res
The positional distribution of fatty acids in palm oil and lard influences their biological effects in rats
J Nutr
Accumulation of lipid and nonlipid constituents in rabbit atheroma
J Atheroscler Res
Comparison of traditional and industrial palm oil
Palm Oil News
Effects of palm oil on cardiovascular risk
Med J Malaysia
The lipid handbook
Palm oil and health
Planter
Developments in food uses of palm oil: a brief review
Palmas
Red palm oil to combat vitamin A deficiency in developing countries
Food Nutr Bull
Vitamin E from palm oil. Its extraction and nutritional properties
Palmas
Cited by (34)
Impact of consumption and cooking manners of vegetable oils on cardiovascular diseases- A critical review
2018, Trends in Food Science and TechnologyCitation Excerpt :Among the vegetable oils, RPO has the maximum content of γ-tocotrienol, proved as the highest antioxidant potential. Experimental and clinical study suggested that RPO offers reduce oxidative stress and protection against reperfusion injury (Bester, Esterhuyse, Truter, & van Rooyen, 2010; Kruger, Engelbrecht, Esterhuyse, du Toit, & van Rooyen, 2007), reduced lipid profile and platelet aggregation (Wilson, Nicolosi, Kotyla, Sundram, & Kritchevsky, 2005). In fact, palm oil has anti-arrhythmogenic effects, which decrease the incidence of sudden death after ischemic (Ong & Goh, 2002).
Cloning, characterization and expression analysis of a 7S globulin gene in mesocarp of oil palm (Elaeis guineensis Jacq.)
2012, Scientia HorticulturaeCitation Excerpt :Researchers have attempted to determine the allergen of 7S globulin to increase the use of edible oils (including palm oil) as healthy foods and to eliminate any possible danger to those allergic to it (Kroghsbo et al., 2011). Similarly, more attention is needed on palm oil if it is to be used to produce antihypertensive drugs (Wilson et al., 2005). Therefore, advanced studies are essential to solve these problems and to clarify the role of 7S globulin both at the molecular and cellular levels.
Evaluation of anti-atherosclerotic activities of PPAR-α, PPAR-γ, and LXR agonists in hyperlipidemic atherosclerosis-susceptible F1B hamsters
2011, AtherosclerosisCitation Excerpt :A recent study in humans also suggested a correlation between extent of atherosclerosis and atherogenic dyslipidemia [28]. Diet-induced hyperlipidemic hamster model has been used by others to evaluate modulation of lipoproteins [23,29] and aortic atherosclerosis [20,22,30–32]. A gender difference in the extent of atherosclerotic lesion formation in hamster model has been reported [31], where females appeared to develop less atherosclerosis compared to males.
Dietary fatty acids and oxidative stress in the heart mitochondria
2011, MitochondrionCitation Excerpt :Coconut oil contains phenolic acids with ROS scavenging and reducing activity, notably ferulic acid and p-coumaric acid (Marina et al., 2009). This oil, even if relatively poor in vitamin E (Masterjohn, 2007), has also been shown to improve the absorption of this vitamin when compared to palm oil (Wilson et al., 2005). A recent study showed that the antioxidant levels in rat testis was lower in animals fed for 60 days with olive or coconut oil compared to more unsaturated fats (grapeseed and soybean oils), and the lowest level of oxidative stress was observed in the rats fed coconut oil (Hurtado de Catalfo et al., 2008).
Impact of dietary fat type within the context of altered cholesterol homeostasis on cholesterol and lipoprotein metabolism in the F1B hamster
2010, Metabolism: Clinical and ExperimentalCitation Excerpt :Coconut oil was used as the experimental saturated fat rather than butter, a more common fat in the diet of humans, because it has been used extensively in prior hamster studies [76,77]. In the hamster, coconut oil has been reported to predominantly increase non-HDL cholesterol concentration, as was observed in the current study, and also has been demonstrated to induce a cytokine response [78-81]. Nonetheless, we observed only a modest response to changing the major dietary fat type with respect to plasma lipid and lipoprotein concentrations, less than anticipated [66,82-85].
Cardiovascular effects of edible oils: A comparison between four popular edible oils
2010, Nutrition Research Reviews
- ☆
The work was supported, in part, by a Research Career Award (HL 00734) to Dr. David Kritchevsky from the National Institute of Health (USA).