Effect of a Palm-Oil Vitamin E Concentrate on the Serum and Lipoprotein Lipids in Humans

Tan DT, Khor HT, Low WH, Ali A, Gapor A.

Am J Clin Nutr. 1991 Apr;53(4 Suppl):1027S-1030S.

The effect of a capsulated palm-oil-vitamin E concentrate (palmvitee) on human serum and lipoprotein lipids was assessed. Each palmvitee capsule contains approximately 18, approximately 42, and approximately 240 mg of tocopherols, tocotrienols, and palm olein, respectively. All volunteers took one palmvitee capsule per day for 30 consecutive days. Overnight fasting blood was taken from each volunteer before and after the experiment. Serum lipids and lipoproteins were analyzed by using the enzymatic CHOD-PAP method. Our results showed that palmvitee lowered both serum total cholesterol (TC) and low-density-lipoprotein cholesterol (LDL-C) concentrations in all the volunteers. The magnitude of reduction of serum TC ranged from 5.0% to 35.9% whereas the reduction of LDL-C values ranged from 0.9% to 37.0% when compared with their respective starting values. The effect of palmvitee on triglycerides (TGs) and HDL-C was not consistent. Our results show that the palmvitee has a hypocholesterolemic effect.

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The Finns average intake of tocopherols, tocotrienols, and vitamin E (alpha-tocopherol equivalents) was determined. The food consumption data were derived mainly from the national food balance sheets (for 1987). The average Finnish daily diet was composed and analyzed both in spring and in autumn in order to minimize the effect of seasonal variation. The four tocopherols and four tocotrienols were then determined using high-performance liquid chromatography (HPLC). For comparison, the intake of vitamin E compounds was also calculated using the most recent Finnish analytical data on tocopherols and tocotrienols in food. According to the analytical results, the average daily vitamin E intake in Finland was 10.7 mg alpha-tocopherol equivalents (alpha-TE) of which amount 85% is due to alpha-tocopherol. The analyzed values (10.8 mg alpha-TE in spring and 10.7 mg alpha-TE in autumn) of vitamin E intake did not markedly differ from the calculated value (10.3 mg alpha-TE), thus indicating that the Finnish food composition data upon tocopherols and tocotrienols is up-to-date and accurate. The best food sources of vitamin E were dietary fat (41% of the total amount), cereals (18%), and dairy products and eggs (13%). The average Finnish diet contained 9.5 g of polyunsaturated fatty acids (PUFA), which leads to the ratio of 0.9 between alpha-tocopherol (mg) and PUFA (g). According to these results, the dietary recommendations for vitamin E are met in Finland.

A major public health concern of affluent nations is the excessive consumption of dietary fats which are now closely linked to coronary heart disease. Against this scenario, the tropical oils and palm oil in particular, have been cast as major villains in the U.S.A., despite the fact that palm oil consumption there is negligible. The unsuspecting public may not realise that the call to avoid palm oil is nothing more than a trade ploy since in recent years palm oil has been very competitive and has gained a major share of the world’s edible oils and fats market. Many also lose sight of the fact that, palm oil, like other edible oils and fats, is an important component of the diet. The allegation that palm oil consumption leads to raised blood cholesterol levels and is therefore atherogenic is without scientific foundation. Examination of the chemical and fatty acid composition of palm oil or its liquid fraction should convince most nutritionists that the oil has little cholesterol-raising potential. The rationale for these are: it is considered cholesterol free. its major saturated fatty acid, palmitic acid (16:0) has recently been shown to be neutral in its cholesterolaemic effect, particularly in situations where the LDL receptors have not been down-regulated by dietary means or through a genetic effect. palm oil contains negligible amounts (less than 1.5%) of the hypercholesterolemic saturated fatty acids, namely lauric acid (12:0) and myristic acid (14:0). it has moderately rich amounts of the hypocholesterolaemic, monounsaturated oleic acid (18:1, omega-9) and adequate amounts of linoleic acid. (18:2, omega-6). It contains minor components such as the vitamin E tocotrienols which are not only powerful antioxidants but are also natural inhibitors of cholesterol synthesis. Feeding experiments in various animal species and humans also do not support the allegation that palm oil is atherogenic. On the contrary, palm oil consumption reduces blood cholesterol in comparison with the traditional sources of saturated fats such as coconut oil, dairy and animal fats. In addition, palm oil consumption may raise HDL levels and reduce platelet aggregability. As with all nutrients, there is a need to obtain a balance of different fatty acids found in fats in edible oils and other food sources. There is no single ideal source of fat that answers to the recent American Heart Association’s call to reflect a 1:1:1 ratio of saturated, monounsaturated and polyunsaturated fats in relation to the recommended dietary fat intake of 30% of calories or less.

Free radical recycling and intramembrane mobility in the antioxidant properties of alpha-tocopherol and alpha-tocotrienol

Serbinova E, Kagan V, Han D, Packer L.

Free Radic Biol Med. February 1991;10(5):263-75.

d-Alpha-tocopherol (2R,4’R,8’R-Alpha-tocopherol) and d-alpha-tocotrienol are two vitamin E constituents having the same aromatic chromanol “head” but differing in their hydrocarbon “tail”: tocopherol with a saturated and toctrienol with an unsaturated isoprenoid chain. d-Alpha-tocopherol has the highest vitamin E activity, while d-alpha-tocotrienol manifests only about 30% of this activity. Since vitamin E is considered to be physiologically the most important lipid-soluble chain-breaking antioxidant of membranes, we studied alpha-tocotrienol as compared to alpha-tocopherol under conditions which are important for their antioxidant function. d-Alpha-tocotrienol possesses 40-60 times higher antioxidant activity against (Fe2+ + ascorbate)- and (Fe2+ + NADPH)-induced lipid peroxidation in rat liver microsomal membranes and 6.5 times better protection of cytochrome P-450 against oxidative damage than d-alpha-tocopherol. To clarify the mechanisms responsible for the much higher antioxidant potency of d-alpha-tocotrienol compared to d-alpha-tocopherol, ESR studies were performed of recycling efficiency of the chromanols from their chromanoxyl radicals. 1H-NMR measurements of lipid molecular mobility in liposomes containing chromanols, and fluorescence measurements which reveal the uniformity of distribution (clusterizations) of chromanols in the lipid bilayer. From the results, we concluded that this higher antioxidant potency of d-alpha-tocotrienol is due to the combined effects of three properties exhibited by d-alpha-tocotrienol as compared to d-alpha-tocopherol: (i) its higher recycling efficiency from chromanoxyl radicals, (ii) its more uniform distribution in membrane bilayer, and (iii) its stronger disordering of membrane lipids which makes interaction of chromanols with lipid radicals more efficient. The data presented show that there is a considerable discrepancy between the relative in vitro antioxidant activity of d-alpha-tocopherol and d-alpha-tocotrienol with the conventional bioassays of their vitamin activity.

The effect of sampling site and closeness of malignant tumor on the retinoid, carotenoid, tocopherol, and tocotrienol concentration of adipose tissue of human breast was studied in 10 cases of breast cancer. The four anatomic quadrants of breast did not differ from each other statistically significantly in relation to adipose tissue concentrations of the vitamins studied. Proximity of malignant tumor did not affect the vitamin concentrations when compared to the more distant sampling sites. Representative sample of breast adipose tissue for vitamin concentration analysis can be obtained from tissue adjacent to the tumor.

This optimization study for tocopherols and tocotrienols involved both normal- and reverse-phase liquid chromatography using various columns and mobile phases. Normal-phase systems showed elution of the homologs in order of increasing polarity with separation based on methyl substituents on the chromanol moiety. Reverse-phase systems showed class separation based on the saturation of the phytyl side chain; the more saturated tocopherols were retained on the column longer. When the Zorbax ODS was used with an isocratic ternary acetonitrile:methanol:methylene chloride (60:35:5) mixture, the optimized resolution was greater than 2.0 and separation was achieved in less than 13 min, but there was no separation of beta- and gamma-tocopherols. The normal-phase silica and amino columns provided separation of all available isomers with resolution greater than 1.1 and separation times of less than 5.5 and less than 10 min, respectively. Optimized isocratic binary solvent mixtures of hexane:2-propanol were used for silica (99:1) and amino (98:2) columns. Derivative spectra showed differences depending on substituents in the chromanol moiety but not the phytyl side chain. Second- and fourth-derivative spectra gave the best differentiation of the vitamin E isomers.

Tocotrienols were evaluated for activity against transplantable murine tumors inoculated i.p. into mouse, and the activities of two tocotrienols and alpha-tocopherols were compared. When the compounds were injected i.p., alpha- and gamma-tocotrienols were effective against sarcoma 180, Ehrlich carcinoma, and IMC carcinoma, and gamma-tocotrienol showed a slight life-prolonging effect in mice with Meth A fibrosarcoma, but thetocotrienols had no antitumor activity against P388 leukemia at doses of 5-40 mg/kg/d. On the other hand alpha-tocopherol had only a slight effect against sarcoma 180 and IMC carcinoma. The antitumor activity of gamma-tocotrienol was higher than that of alpha-tocotrienol. Tocotrienols showed growth inhibition of human and mouse tumor cells when the cells were exposed to these agents for 72 h in vitro, whereas tocopherol did not show any marked cytotoxic activity. Alpha- and gamma-tocotrienols had inhibitory effects on lipid peroxidation of murine microsomes by adriamycin.

Effect of dietary palm oils on mammary carcinogenesis in female rats induced by 7,12-dimethylbenz(a)anthracene

Sundram K, Khor HT, Ong AS, Pathmanathan R.

Cancer Res. 1989 Mar 15;49(6):1447-51.

Female Sprague-Dawley rats, 50 days of age, were treated with a single dose of 5 mg of 7,12-dimethylbenz(a)anthracene intragastrically. 3 days after carcinogen treatment, the rats were put on semisynthetic diets containing 20% by weight of corn oil (CO), soybean oil (SBO), crude palm oil (CPO), refined, bleached, deodorized palm oil (RBD PO) and metabisulfite-treated palm oil (MCPO) for 5 months. During the course of experiments, rats fed on different dietary fats had similar rate of growth. Rats fed 20% CO or SBO diet have higher tumor incidence than rats fed on palm oil (PO) diets; however differences of mean tumor latency periods among the groups were not statistically significant. At autopsy, rats fed on high CO or SBO diets had significantly more tumors than rats fed on the three PO diets. Our results showed that high PO diets did not promote chemically induced mammary tumorigenesis in female rats when compared to high CO or SBO diets. CO and SBO differ greatly from the palm oils in their contents of tocopherols, tocotrienols, and carotenes. But further experiments would be required to determine whether the observed differences in tumor incidence and tumor numbers were due to the differences in these minor components or due to the unique triglyceride structure of the palm oils. Analysis of the fatty acid profiles of plasma total lipids of tumor-bearing rats and of the tumor total lipids showed that, with the exception of arachidonic acid, the fatty acid profiles reflect the nature of the dietary fats. At autopsy, there were no differences in the plasma total cholesterol contents among rats fed on different dietary fats, but rats fed on palm oil diets had a significantly higher plasma triglyceride level than that of rats fed CO or SBO diets. As for the tumor lipids, there were no significant differences in the triglyceride, diglyceride, and phospholipid levels when the CO or SBO groups were compared to the palm oil groups.

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Tandem mass spectrometry is applied to the tocopherols and representative tocotrienols of the vitamin E family. The collision-induced dissociation/mass analysed ion kinetic energy spectra generated from three ions in the electron impact ionization spectra of 5,7,8-trimethyltocol, 5,7,8-trimethyltocotrienol, 5,7-, 5,8- and 7,8-dimethyltocol and 7,8-dimethyltocotrienol are described. The technique allowed direct physical characterization of each class of tocochromanol, and in the case of monomethyltocols differentiation of 5-methyltocol from the 7- and 8-methyltocol isomers, and its value in analysis of biological tissue extracts is established.

Purification of the oily, nonpolar fraction of high protein barley (Hordeum vulgare L.) flour by high pressure liquid chromatography yielded 10 major components, two (I, II) of which were potent inhibitors of cholesterogenesis in vivo and in vitro. The addition of purified inhibitor I (2.5-20 ppm) to chick diets significantly decreased hepatic cholesterogenesis and serum total and low density lipoprotein cholesterol and concomitantly increased lipogenic activity. The high resolution mass spectrometric analysis and measurement of different peaks of inhibitor I gave a molecular ion at m/e 424 (C29H44O2) and main peaks at m/e 205, 203, and 165 corresponding to C13H17O2, C13H15O2, and C10H13O2 moieties, respectively. which are characteristic of d-alpha-tocotrienol. This identification was confirmed against synthetic samples. The tocotrienols are widely distributed in the plant kingdom and differ from tocopherols (vitamin E) only in three double bonds in the isoprenoid chain which appear to be essential for the inhibition of cholesterogenesis.