High-performance liquid chromatographic determination of tocopherols and tocotrienols and its application to diets and plasma of Finnish men. II. Applications

The composed one-day diets and plasma of 40 Finnish men screened for a selenium supplementation study were analyzed for tocopherols and tocotrienols. The men were divided into a low-Se group (in the screening phase plasma Se levels less than 70 micrograms/l and plasma alpha-tocopherol levels less than 1.2 mg/100 ml) and a high-Se group (plasma Se greater than 70 micrograms/l, plasma alpha-tocopherol not determined before the study). In the low-Se group plasma levels of alpha-tocopherol averaged 0.97 +/- 0.18 mg/100 ml. The daily dietary intake of alpha-tocopherol was 6.1 +/- 2.7 mg and that of total vitamin E 7.3 +/- 3.1 mg of alpha-tocopherol equivalents. In the high-Se group the corresponding average values were 1.16 +/- 0.21 mg of alpha-tocopherol/100 ml of plasma, 8.8 +/- 4.3 mg of alpha-tocopherol/day and 10.3 +/- 5.1 mg of alpha-tocopherol equivalents/day. The overall average for the contribution of alpha-tocopherol to the total dietary tocopherols was 44.6 +/- 11.0%. In the plasma samples alpha-tocopherol accounted for 92.0 +/- 2.1%, beta-tocopherol for 2.7 +/- 0.7% and gamma-tocopherol for 5.3 +/- 2.1% of the total amount of tocopherols.     

Tocopherols and tocotrienols in Finnish foods: human milk and infant formulas

Individual tocopherols and tocotrienols in human milk, mother's milk substitutes and other infant formulas have been determined by an HPLC method. 107 human milk samples (23 colostral, 22 transitional and 62 mature) obtained from six healthy mothers throughout the lactation were found to contain all the tocopherols, although delta-tocopherol occurred only in traces. A high content of alpha-tocopherol was found in colostrum (average 1.90 +/- 1.62 (SD) mg/100 g), as compared with transitional (0.65 +/- 0.22 mg/100 g) and mature milk (0.47 +/- 0.16 mg/100 g). The content of beta-tocopherol averaged 0.05 +/- 0.03, 0.02 +/- 0.01 and 0.02 +/- 0.01 and gamma-tocopherol 0.11 +/- 0.09, 0.07 +/- 0.04 and 0.07 +/- 0.04 mg/100 g in colostral, transitional and mature milk respectively. The alpha-tocopherol equivalents thus were 1.93, 0.66 and 0.49 mg/100 g; their ratios to the contents of polyunsaturated fatty acids meet the nutritional need of the newborn and young infant: 5.7, 2.1 and 1.4 mg/g in colostral, transitional and mature milk. Mother's milk substitutes and gruel and porridge powders are enriched with tocopherol acetate to vitamin E levels similar to or higher than those in human milk: substitutes contained on average 1.4 mg alpha-tocopherol equivalents/100 g and reconstituted powders 1.1 mg/100 g. The ratio of vitamin E to polyunsaturated fatty acids of these infant formulas was higher than the recommended value of 0.6 mg/g. The average values for alpha-tocopherol equivalents in fruit-berry and meat-vegetable infant formulas were 0.46 and 0.38 mg/100 g.     

Corn and sesame oils increase serum gamma-tocopherol concentrations in healthy Swedish women

We studied the effects of dietary intervention with three vegetable oils (Linola, corn or sesame oil, all good sources of gamma-tocopherol) on absolute and relative concentrations of alpha- and gamma-tocopherol in human serum. The oils contained only small amounts of linolenic acid but varying amounts of oleic and linoleic acids, and they had different concentrations of alpha-tocopherol. Forty healthy female students (mean age 26 y) were randomly assigned to one of three groups and consumed a diet that contained one of the three oils for 4 wk. Refined oils were distributed as ingredients in specially prepared buns, in margarine or as dressing. Serum tocopherols, serum lipoproteins and plasma malondialdehyde concentrations were measured. The gamma-tocopherol concentrations normalized to serum lipids increased significantly in the corn and sesame oil groups (P < 0.01), and the alpha-/gamma-tocopherol ratios decreased significantly from baseline concentrations in all groups (P < 0.05). The alpha-tocopherol concentrations did not change during the diet period in any of the three groups. Serum cholesterol, serum apolipoprotein B and plasma malondialdehyde concentrations decreased significantly only in the Linola oil group (P < 0.05). These data show that a moderately modified natural diet that contains both alpha- and gamma-tocopherol increases the serum gamma-tocopherol concentration in healthy women without affecting the serum alpha-tocopherol concentration.     

Effect of the main dietary antioxidants (carotenoids, gamma-tocopherol, polyphenols, and vitamin C) on alpha-tocopherol absorption

OBJECTIVE: (R,R,R)-alpha-tocopherol is a fat-soluble antioxidant vitamin generally ingested with other dietary antioxidants. The objective of this study was to assess whether the main dietary antioxidant classes, that is carotenoids, polyphenols, vitamin C and gamma-tocopherol, affect the intestinal absorption of alpha-tocopherol. METHODS, DESIGN AND SUBJECTS: We evaluated first the effect of different combinations of antioxidants on (R,R,R)-alpha-tocopherol absorption by a human intestinal cell line (Caco-2 clone TC7). Then we compared the effect of two doses of a dietary antioxidant (lutein) on the postprandial chylomicron alpha-tocopherol responses to an alpha-tocopherol-rich meal. Eight healthy men ate two similar meals in a random order at a 1 month interval. The meals contained 24 mg alpha-tocopherol in sunflower oil plus either 18 or 36 mg lutein. Blood samples were collected during the postprandial periods to compare chylomicron alpha-tocopherol responses. RESULTS: A mixture of polyphenols (gallic acid, caffeic acid, (+)-catechin and naringenin) and a mixture of carotenoids (lycopene, beta-carotene and lutein) significantly impaired alpha-tocopherol absorption in Caco-2 cells (P<0.001 and P<0.0001, respectively). The inhibitory effect of gamma-tocopherol was close to significance (P=0.055). In contrast, vitamin C had no significant effect (P=0.158). Naringenin was the only polyphenol that significantly impaired alpha-tocopherol absorption. Postprandial alpha-tocopherol response was weakest at the highest dose of lutein (616+/-280 nmol/l h vs 1001+/-287 nmol/l h). The observed extent of reduction (-38%, P=0.069) supported the inhibitory effect of carotenoids observed in the Caco-2 experiments. CONCLUSION: Naringenin, carotenoids and probably gamma-tocopherol can impair alpha-tocopherol absorption whereas vitamin C and phenolic acids have no effect.     

Supplementation with mixed tocopherols increases serum and blood cell gamma-tocopherol but does not alter biomarkers of platelet activation in subjects with type 2 diabetes

BACKGROUND: Some studies have shown potential benefit of vitamin E on platelet function, but several clinical trials failed to show improved cardiovascular outcome with alpha-tocopherol supplementation. Gamma-tocopherol, a major dietary form of vitamin E, may have protective properties different from those of alpha-tocopherol. OBJECTIVE: We compared the effects of supplementation with alpha-tocopherol (500 mg) and a gamma-tocopherol-rich compound (500 mg, containing 60% gamma-tocopherol) on serum and cellular tocopherol concentrations, urinary tocopherol metabolite excretion, and in vivo platelet activation in subjects with type 2 diabetes. DESIGN: Fifty-eight subjects were randomly assigned to receive either 500 mg alpha-tocopherol/d, 500 mg mixed tocopherols/d, or matching placebo. Serum, erythrocyte, and platelet tocopherol and urinary metabolite concentrations were measured at baseline and after the 6-wk intervention. Soluble CD40 ligand, urinary 11-dehydro-thromboxane B2, serum thromboxane B2, soluble P-selectin, and von Willebrand factor were measured as biomarkers of in vivo platelet activation. RESULTS: Serum alpha-tocopherol increased with both tocopherol treatments. Serum and cellular gamma-tocopherol increased 4-fold (P < 0.001) in the mixed tocopherol group, whereas red blood cell gamma-tocopherol decreased significantly after alpha-tocopherol supplementation. Excretion of alpha-carboxyethyl-hydroxychroman increased significantly after supplementation with alpha-tocopherol and mixed tocopherols. Excretion of gamma-carboxyethyl-hydroxychroman increased significantly after supplementation with mixed tocopherols and after that with alpha-tocopherol, which may reflect the displacement of gamma-tocopherol by alpha-tocopherol due to incorporation of the latter into lipoproteins in the liver. Neither treatment had any significant effect on markers of platelet activation. CONCLUSIONS: Supplementation with alpha-tocopherol decreased red blood cell gamma-tocopherol, whereas mixed tocopherols increased both serum alpha-tocopherol and serum and cellular gamma-tocopherol. Changes in serum tocopherol closely reflect changes in cellular concentrations of tocopherols after supplementation.     

Balance of unsaturated fatty acids is important to a cholesterol-lowering diet: comparison of mid-oleic sunflower oil and olive oil on cardiovascular disease risk factors

OBJECTIVE: To evaluate the effects of a trans fat-free monounsaturated fatty acid-rich vegetable oil (NuSun sunflower oil, National Sunflower Association, Bismark, ND) that is a good source of polyunsaturated fatty acids (PUFA) and low in saturated fatty acids on lipid and lipoprotein levels and oxidative stress. DESIGN: A double-blinded, randomized, three period crossover, controlled feeding study. SUBJECTS/SETTING: Thirty-one men (n=12) and women (n=19) with moderate hypercholesterolemia who were 25 to 64 years of age. INTERVENTION: Experimental diets provided 30% fat (olive oil or NuSun sunflower oil contributed one half of the total fat), 8.3% vs 7.9% saturated fatty acid, 17.2% vs 14.2% monounsaturated fatty acid, and 4.3% vs. 7.7% PUFA (olive oil and NuSun sunflower oil, respectively), and 294 mg cholesterol. The control diet was an average American diet (34% fat, 11.2% saturated fatty acid, 14.9% monounsaturated fatty acid, 7.8% PUFA). Subjects consumed each diet for 4 weeks with a 2-week compliance break before crossing over to another diet. MAIN OUTCOME MEASURES: Lipid and lipoprotein levels were measured, and measures of oxidative stress, including lag time, rate of oxidation, total dienes, and lipid hydroperoxides, were assessed. STATISTICAL ANALYSIS: The mixed model procedure was used to test for main effects of diet, feeding period, and order of diets. Tukey-Kramer adjusted P values were used to determine diet effects. RESULTS: The NuSun sunflower oil diet decreased both total and low-density lipoprotein cholesterol levels compared with the average American diet and the olive oil diet. There was no effect of the olive oil diet compared with the average American diet. Total cholesterol decreased 4.7% and low-density lipoprotein cholesterol decreased 5.8% on the NuSun sunflower oil diet vs the average American diet. There was no effect of the experimental diets on triglyceride levels, rate of oxidation, total dienes, lipid hydroperoxides, or alpha-tocopherol. Lag time was the longest following the olive oil diet and shortest following the NuSun sunflower oil diet. CONCLUSIONS: The higher PUFA content appeared to account for the greater total and low-density lipoprotein cholesterol lowering and reduction in lag time of the NuSun sunflower oil diet. However, the fact that there were no differences in the resulting oxidation products suggests there were no adverse effects on low-density lipoprotein oxidation. Since PUFAs are important for cholesterol lowering, foods that replace saturated fatty acids should include a balance of unsaturated fatty acids.     

Dietary antibiotic growth promoters enhance the bioavailability of alpha-tocopheryl acetate in broilers by altering lipid absorption

The influence of intestinal microbial bile salt deconjugation on absorption of fatty acids and alpha- and gamma-tocopherol was investigated in a trial with Ross 208 broilers. Birds (n = 1600) were assigned to 4 dietary treatments: no supplementation or supplementation of antibiotics (salinomycin, 40 mg/kg feed and avilamycin, 10 mg/kg feed), and inclusion of either animal fat (10 g/100 g feed) or soybean oil (10 g/100 g feed) in the diet. At d 7, 14, 21, and 35 of age, the intestinal number of the bile salt hydrolase-active bacteria Clostridium perfringens, the concentration of conjugated and unconjugated bile salts, the ileal absorption of fatty acids and tocopherols, and the blood plasma concentrations of tocopherols were measured. All variables were significantly influenced by bird age. C. perfringens counts were lower and bile salt concentrations were greater in birds fed soybean oil. The supplementation of antibiotics reduced the numbers of C. perfringens in the small intestine and reduced the concentration of unconjugated bile salts. The ileal absorption of fatty acids and alpha-tocopherol, as well as the plasma concentration of alpha-tocopherol, was greater in birds fed antibiotics. The absorption and plasma concentration of gamma-tocopherol were not influenced by antibiotics. Unlike gamma-tocopherol, which is present solely as the free alcohol, the major proportion of dietary alpha-tocopherol is present as alpha-tocopheryl acetate, which requires a bile salt-dependent enzymatic hydrolysis before absorption. In conclusion, proper digestion of lipid-soluble compounds is highly dependent on an adequate concentration of bile salts in the small intestine to provide proper lipid emulsification and activation of lipolytic enzymes.     

Effect of dietary lipids on hepatic and intestinal monooxygenases in mice

The effect of dietary lipids on hepatic and intestinal monooxygenases was studied by feeding C57BL/6N mice (for 2 wks) diets containing 5% and 23.5% (wt/wt) olive oil or corn oil. At the end of the feeding period, we measured arylhydrocarbon hydroxylase (AHH) activity in S9 preparations from liver, small intestine, and colon; and, using the same S9 preparations from the liver, we observed the activation of the following three dietary promutagens: 2-amino-3-methylimidazo(4,5-f)quinoline, 2-amino-3,8-dimethylimidazo(4,5-f) quinoxaline, and 2-amino-6-methyldipyrido(1,2-a:3',2'-d)imidazole. The results showed that high-fat diets increased hepatic AHH activity both in corn oil and olive oil diets compared with the low-fat diets; also, a 5% corn oil diet had significantly higher AHH activity compared with the 5% olive oil diet. AHH activity was, respectively, 48.6 +/- 5.1 and 79.5 +/- 11.4 pmol 3OH-benzo[a]pyrene formed/mg/min in the 5% and 23.5% olive oil diets and 66.1 +/- 5.1 and 83.9 +/- 12.2 in the 5% and 23.5% corn oil diets; values are means +/- SE, n = 16. The results also showed a significant increase in the ability of hepatic S9 fractions from animals on high-fat diets to activate promutagens in the Salmonella/plate test. On the contrary, AHH activity in the small intestine and colon was not affected by the fat content of the diet.     

No effects of olive oils with different phenolic content compared to corn oil on 1,2-dimethylhydrazine-induced colon carcinogenesis in rats

BACKGROUND: Some epidemiological and experimental studies suggest that olive oil, despite its elevated caloric content, may have protective activity against colon cancer, partially due to its phenolic content. However, little experimental evidence exists to support this claim in vivo. AIM OF THE STUDY: To test the effect of olive oils with different phenolic content in a well-characterized model of colon carcinogenesis, comparing them with corn oil (CO). METHODS: F344 rats were fed AIN-76 based diets for the entire experimental period; the diets contained 23% (w/w) of lipids from three different sources: extra-virgin olive oil rich in phenolic compounds (EV), rectified olive oil (ROO) with the same fatty acid composition but devoid of phenolic compounds and CO as a control diet. One week later, rats were induced with 1,2-dimethylhydrazine (DMH) (150 mg/kg b.w. x 2 times) to measure preneoplastic lesions (aberrant crypt foci (ACF) and mucin depleted foci (MDF)) and tumours in the intestine. RESULTS: Thirteen weeks after DMH, the numbers of ACF and MDF were similar in the different groups (ACF/colon were 344.9 +/- 27.0, 288.6 +/- 28.5 and 289.8 +/- 21.4 in CO, EV and ROO groups, respectively, means +/- SE; MDF/colon were 8.83 +/- 1.2, 8.41 +/- 1.5 and 8.75 +/- 1.6 in CO, EV and ROO groups, respectively, means +/- SE). Thirty-two weeks after DMH, the incidence of tumours (rats with tumours/rats in the group) did not differ among the different groups (20/21, 18/19 and 20/20 in the CO, EV, and ROO groups, respectively). Similarly, the number of tumours/ rat in the colorectum (both adenomas and cancers) was not different in the three different groups (2.33 +/- 0.26, 2.42 +/- 0.41 and 2.25 +/- 0.40 in CO, EV and ROO groups, respectively, means +/- SE). CONCLUSIONS: Olive oil, irrespective of its phenolic content, does not affect DMH-induced colon carcinogenesis in F344 rats compared with CO.     

Comparison of an oleic acid enriched-diet vs NCEP-I diet on LDL susceptibility to oxidative modifications

OBJECTIVE: The objective of this trial was to compare the effect on the susceptibility of plasma Low Density Lipoprotein (LDL) to oxidative modifications of consumption of two oleic rich diets, prepared with two different plant oils, virgin olive oil (OL)1 and refined high monounsaturated fatty acids (MUFA sunflower oil (SU)), with the susceptibility of plasma LDL to oxidation after an National Cholesterol Education Program step 1 (NCEP-I) phase diet. DESIGN: A randomized crossover design. SUBJECTS AND INTERVENTIONS: Twenty-two healthy normolipidemic young males consumed an NCEP-I diet for a 4-week period. Subjects were then assigned to two diets each of 4-weeks duration. Group one was placed on an olive oil enriched diet (40% fat, 22% MUFA) followed by a 4-week period of a MUFA diet enriched in sunflower oil (40% fat, 22% MUFA). In group two, the order of the diets was reversed. RESULTS: Both MUFA diets induced a decrease in saturated (14:0, 16:0, and 18:0) and an increase in monounsaturated and polyunsaturated n-6 (18:2, 20:3, and 20:5) plasma LDL-phospholipid fatty acids, compared to the NCEP-I diet (P<0.01). No significant differences in lag times were observed between the olive oil and the NCEP-I diet periods. However there was a greater inhibition time (P<0.001) when subjects consumed the MUFA rich sunflower oil diet compared to the NCEP-I diet. These differences were probably related to the relative enrichment of plasma LDL particles in alpha-tocopherol due to the high vitamin E content of the MUFA-rich sunflower oil. Indeed, the alpha-tocopherol content was positively correlated with lag time (r=0.338; P<0.008). CONCLUSION: Our findings suggest that changes in plasma LDL alpha-tocopherol content with practical solid-food diets can decrease its susceptibility to oxidation. SPONSORSHIP: This work has been supported by grants from the Investigaciones de la Seguridad Social (FIS 92/0182, to Francisco Pérez Jiménez); and from Koype Co, Andújar, Jaén, Spain. European Journal of Clinical Nutrition (2000) 54, 61-67     

Population-based study of alpha- and gamma-tocopherol in plasma and adipose tissue as biomarkers of intake in Costa Rican adults

BACKGROUND: gamma-Tocopherol is the most abundant form of vitamin E in the US diet, but alpha-tocopherol concentrations are the highest in plasma and tissues. Although plasma and adipose tissue concentrations of alpha-tocopherol have been used as biomarkers of intake, the relation between gamma-tocopherol intake and concentrations in plasma and adipose tissue is unknown. OBJECTIVE: Our goal was to investigate in a randomly selected population from Costa Rica whether plasma or adipose tissue concentrations of alpha- and gamma-tocopherol are suitable biomarkers of intake. DESIGN: A total of 361 men (x +/- SD age: 55 +/- 11 y) and 121 women (aged 59 +/- 10 y) completed a 135-item food-frequency questionnaire and provided a fasting blood sample and adipose tissue biopsy sample. RESULTS: Dietary gamma-tocopherol correlated with adipose tissue (r = 0.37, P < 0.001) and plasma (r = 0.42, P < 0.001) concentrations, regardless of supplement use. Dietary alpha-tocopherol correlated poorly with adipose tissue (r = 0.15, P < 0.01) and plasma (r = 0.16, P < 0.001) concentrations, and these correlations were even lower when users of vitamin supplements (n = 24) were excluded (adipose tissue: r = 0.10, P < 0.05; plasma: r = 0.09, P < 0.05). Compared with subjects who reported palm shortening (36%) as the major type of fat used for cooking, subjects using soybean oil (52%) had higher amounts of both alpha- and gamma-tocopherol in their diets. However, only gamma-tocopherol concentrations were higher in the plasma and adipose tissue of soybean oil users. CONCLUSIONS: Plasma and adipose tissue concentrations of gamma-tocopherol are equally good biomarkers of intake. The weak associations between alpha-tocopherol intake and plasma or adipose tissue concentrations suggest that these biomarkers are influenced more by factors other than alpha-tocopherol intake.     

Distribution of serum concentrations of alpha-tocopherol and gamma-tocopherol in the US population

BACKGROUND: Although the population distribution of serum concentrations of alpha-tocopherol has been described in the United States, little is known about the distribution of gamma-tocopherol or the ratio of alpha-tocopherol to gamma-tocopherol. OBJECTIVE: Our aim was to describe the distribution of serum concentrations of alpha-tocopherol and gamma-tocopherol in a nationally representative sample of US adults. DESIGN: We reviewed data from 4087 adults aged >/=20 y who participated in the National Health and Nutrition Examination Survey (1999-2000). Concentrations of alpha-tocopherol and gamma-tocopherol were measured by using HPLC with ultraviolet-visible wavelength detection. RESULTS: The arithmetic mean (+/-SEM) of serum concentrations of alpha-tocopherol was 30.09 +/- 0.45 micromol/L, the median was 25.94 micromol/L, and the geometric mean (+/-SEM) was 27.39 +/- 0.38 micromol/L. The arithmetic mean of serum concentrations of gamma-tocopherol was 5.74 +/- 0.22 micromol/L, the median was 5.25 micromol/L, and the geometric mean was 4.79 +/- 0.18 micromol/L. The median ratio of alpha-tocopherol to total cholesterol was 4.93 micromol/mmol, that of gamma-tocopherol to total cholesterol was 1.03 micromol/mmol, and that of alpha-tocopherol to gamma-tocopherol was 4.53 micromol/mmol. Concentrations of alpha-tocopherol increased significantly (P for trend < 0.001) with age and were significantly (P = 0.015) lower in men than in women. African Americans and Mexican Americans had significantly (P < 0.001) lower concentrations of alpha-tocopherol than did whites. The median concentrations of gamma-tocopherol showed a trend with respect to age, did not differ significantly between men and women, and were slightly but nonsignificantly lower in white participants than in African American or Mexican American participants. CONCLUSION: Sociodemographic variations in serum concentrations of alpha-tocopherol and gamma-tocopherol exist among US adults.     

Effect of meal fat quality on oxidation resistance of postprandial VLDL and LDL particles and plasma triacylglycerol level

This study was performed to examine the postprandial effects of meals containing dietary fats, with their natural fatty acid composition and tocopherol content, on the plasma triacylglycerols (TG) and tocopherols and on the resistance of VLDL and LDL to oxidation. On six separate days eighteen healthy male subjects were given low-fat meals (LF) or the LF meals enriched with sunflower oil (SO), rapeseed oil (RO), olive oil (OO), palm oil (PO), or butter (B) in a crossover design. The fat-rich meals all resulted in similar postprandial TG responses while the LF test meal did not increase plasma TG level. The postprandial plasma fatty acid profile changed to resemble the fatty acid composition of the ingested test fat. The alpha-tocopherol:gamma-tocopherol ratios in postprandial plasma and VLDL samples were greater than in the test fats. We found that the resistance of VLDL particles to oxidation in the postprandial state as assessed from lag time was increased after the PO-rich meal as compared with the SO-rich meal (p = 0.018), and the propagation rate was greater after the SO- and RO-rich meals compared with the others (p < 0.001). The resistance of LDL particles to oxidation was unaffected by the meals. In postprandial VLDL samples, the content of alpha-tocopherol was greater after the OO- and SO-rich meals compared with the meal rich in PO (P = 0.034 and 0.042 respectively). The gamma-tocopherol content of VLDL was highest after RO-meal as compared with all other test meals (P = 0.0019), and higher after SO as compared with B (P = 0.0148). Large individual differences were noted. In conclusion, meals enriched with different fats lead to the formation of VLDL particles with varying resistance to oxidation.     

Sunflower oil does not protect against LDL oxidation as virgin olive oil does in patients with peripheral vascular disease

BACKGROUND & AIMS: The aim of this study was to compare the in vivo effects of a diet rich in virgin olive oil or sunflower oil on the lipid profile and on LDL susceptibility to oxidative modification in free-living Spanish male patients with peripheral vascular disease. METHODS: A total of 20 Spanish male subjects diagnosed with peripheral vascular disease were randomly divided into two groups (n = 10) receiving different supplements, virgin olive oil and sunflower oil for 4 months. RESULTS: The adaptation of patients to the experimental supplements was demonstrated since plasma and LDL fatty acids composition reflected dietary fatty acids. No differences in triglycerides, total cholesterol, LDL-cholesterol or HDL-cholesterol concentrations were found between the groups of patients. A significantly higher LDL susceptibility to oxidation was observed after sunflower oil intake in comparison with virgin olive oil, in spite of an increase in LDL alpha-tocopherol concentration in sunflower oil group. CONCLUSIONS: The results of the present study provide further evidence that sunflower-oil-enriched diets does not protect LDL against oxidation as virgin olive oil does in patients with peripheral vascular disease.     

The effect of dietary fat saturation on plasma and hepatic lipoproteins in the rat

Semipurified diets containing 10% kilocalories from either safflower oil (SO), corn oil (CO), olive oil (OO) or palm oil (PO) were fed to weanling male rats for 2 weeks. The effects of dietary fat saturation on plasma lipids and lipoproteins were: 1) Nonfasted plasma cholesterol concentration was higher in rats fed OO (mean +/- SEM = 81.0 +/- 2.9 mg/dl) vs. CO (67.5 +/- 2.9); 2) plasma chylomicron cholesterol concentration was higher in rats fed OO vs. SO and CO, with PO values in between; and 3) the cholesterol concentration of plasma very low density lipoprotein (VLDL), low density lipoprotein (LDL) and high density lipoprotein (HDL) did not differ among groups. The effects of dietary fat saturation on hepatic lipoproteins (determined by liver perfusion techniques) were: 1) hepatic higher density lipoprotein (d = 1.006-1.21 g/ml) cholesterol production was greater in rats fed SO and CO vs. PO [19.1 +/- 1.2, 17.2 +/- 0.8 and 13.7 +/- 1.6 micrograms/(g liver X 1.5 hour), respectively]; 2) there was no difference in hepatic VLDL cholesterol production among groups; and 3) the ratio of cholesterol to protein of hepatic VLDL and the higher density lipoprotein fraction was higher in rats fed diets rich in polyunsaturated fatty acids versus saturated fatty acids. Dietary fat saturation had no effect on carcass and liver cholesterol concentrations. Since differences in hepatic lipoprotein production were not reflected in plasma lipoprotein patterns, these results suggest that extrahepatic lipoprotein metabolism differs in rats fed diets containing fatty acids of varying saturation.     

Olive oil prevents the adverse effects of dietary conjugated linoleic acid on chick hatchability and egg quality

Dietary conjugated linoleic acid (CLA) decreases yolk 18:1(n-9), induces chick embryonic mortality and alters egg quality. A study was conducted to determine whether olive oil would prevent these adverse effects of CLA. Hens (15 per treatment) were fed diets containing 0.5 g corn oil/100 g (CO), 0.5 g CLA/100 g (CLA), 0.5 g corn oil plus 10 g olive oil/100 g (CO + OO) or 0.5 g CLA plus 10 g olive oil/100 g (CLA + OO). After 74 d of feeding, hens were placed on CO for 10 d. Hens were artificially inseminated weekly. For hatchability studies, fertile eggs were collected daily, stored at 15 degrees C for 24 h and then incubated. After 6 d of feeding, embryonic mortality rates were 15, 100, 8 and 16% in the CO, CLA, CO + OO and CLA + OO groups, respectively. When CLA-fed hens were fed the CO diet, hatchability improved to that of the CO group within 7 d. For fatty acid analysis, three eggs were obtained at the 7 d of feeding. Relative CLA levels of yolk from CO-, CLA-, CO + OO- and CLA + OO-fed hens were 0.11 +/- 0.01, 1.91 +/- 0.16, 0.08 +/- 0.04 and 0.69 +/- 0.07 g/100 g fatty acids, respectively. The ratios of 16:0/16:1(n-7) and 18:0/18:1(n-9) of yolk from CLA-fed hens were approximately 1- and approximately 1.5-fold greater, respectively, compared with those fed CO. OO prevented CLA-induced increases in 16:0 and 18:0 and the decrease in 18:1(n-9) in yolk. Fertile eggs were stored at 4 degrees C for 2 or 10 wk and analyzed for pH or mineral levels. Dietary CLA caused abnormal pH changes of albumen and yolk when eggs were stored at 4 degrees C. The pH of yolk and albumen from CO-fed hens after 10 wk of storage was 6.12 +/- 0.12 and 9.06 +/- 0.03, respectively, versus 7.89 +/- 0.25 and 8.32 +/- 0.16, respectively, in eggs from CLA-fed hens. OO prevented CLA-induced abnormal changes in the pH of albumen and yolks. Eggs from CLA-fed hens had greater iron, calcium and zinc concentrations and lower magnesium, sodium and chloride concentrations in albumen relative to those from hens fed CO. OO prevented CLA-induced mineral exchange between yolk and albumen, presumably by reducing the yolk saturated fatty acids, which are believed to disrupt the vitelline membrane during cold storage. This study suggests that the adverse effects of CLA may be due to the increased level of saturated fatty acids. However, because the addition of olive oil also lowered egg CLA content, the direct role of egg CLA on egg hatchability and quality cannot be ruled out.     

The tocopherol, tocotrienol, and vitamin E content of the average Finnish diet.

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.     

Controlled evaluation of fat intake in the Mediterranean diet: comparative activities of olive oil and corn oil on plasma lipids and platelets in high-risk patients

Activities of low-fat diets with olive oil or corn oil on lipids and platelets were studied in 23 middle-aged patients with high atherosclerosis risk for 8 wk. The olive oil diet had a polyunsaturated-saturated ratio of 0.33 vs 1.28 for the corn oil diet. Plasma total cholesterol was reduced with corn oil, but high-density lipoprotein cholesterol levels were lower with corn oil and unchanged or raised by olive. Plasma apolipoprotein B levels were equally reduced by both diets; apolipoprotein AI and the apo AI:B ratio rose only with olive oil. Plasma-glucose levels were lowered significantly with olive oil. Changes in platelet function were characterized by a reduced sensitivity to arachidonic acid (particularly with corn oil) and to collagen (particularly with olive). An olive oil diet with a moderate fat intake (about 30% of total calories) leads to favorable plasma lipoprotein and platelet changes.     

Dietary oils high in oleic acid but with different unsaponifiable fraction contents have different effects in fatty acid composition and peroxidation in rabbit LDL

OBJECTIVE: We investigated the influence of different edible oils high in oleic acid but with different unsaponifiable fractions on the fatty acid composition and lipid peroxidation in plasma and low-density lipoprotein (LDL) in rabbits. METHODS: Thirty-two rabbits were randomly assigned to four groups of eight animals. For 8 wk each group was fed a semisynthetic isoenergetic diet that differed by lipid source (Picual virgin olive oil, Picual virgin olive oil that had been subjected to an exhaustive process of washing, Arbequina virgin olive oil, and sunflower oil high in oleic acid). We analyzed the fatty acid profile, thiobarbituric acid reactive substances, alpha-tocopherol, coenzyme Q, and retinol in plasma and the fatty acid profile, hydroperoxides, alpha-tocopherol, and coenzyme Q in LDL. RESULTS: The two varieties of virgin olive oil behaved differently from the high-oleic sunflower oil, and the effect of the different ratios of oleic acid to linoleic acid in the lipid sources on fatty acid composition in plasma and LDL was significant. With regard to oxidative stress, LDL in the group that ingested the lipid sources with the greatest amount of phenolic compounds showed the highest level of antioxidants (alpha-tocopherol and coenzyme Q; P < 0.05) and the lowest susceptibility to lipid peroxidation (P < 0.05). CONCLUSION: This study provides evidence in vivo of the considerable antioxidant capacity of the phenolic fraction of virgin olive oil in rabbit LDL and the important role that this unsaponifiable fraction can play in the overall antioxidant benefit attributed to these oils. However, these effects depend on the phenolic content of the oil.     

Dietary (n-3) fatty acid and vitamin E interactions in rats: effects on vitamin E status, immune cell prostaglandin E production and primary antibody response.

To examine the interaction between dietary fat and vitamin E at the level of the rat immune system, a 2 x 3 factorial study was designed. Weanling female Sprague Dawley rats were fed for 8-9 wk diets that contained either corn oil (CO diet) or fish oil (FO diet) and one of three levels (30, 300, 900 mg/kg) of all-rac-alpha-tocopheryl acetate. At the lowest level of dietary vitamin E, alpha-tocopherol content of splenocytes from FO-fed rats was approximately 40% lower (P less than 0.05) than in those from CO-fed rats. Supplementation with all-rac-alpha-tocopheryl acetate elevated alpha-tocopherol in splenocytes from FO-fed rats but not in those from CO-fed rats, and reduced the relative proportion of arachidonic acid and eicosapentaenoic acid in the serum of CO-fed and FO-fed rats, respectively. Prostaglandin E production by isolated immune cells was not affected by all-rac-alpha-tocopheryl acetate supplementation. However, feeding the FO diet consistently reduced prostaglandin E synthesis by 70-80% as compared with the CO diet. Antibody production against sheep RBC was highest in rats fed the FO diet supplemented with 900 mg all-rac-alpha-tocopheryl acetate/kg of diet. However, antibody response was not directly correlated to diet-induced changes in immune cell prostaglandin E production or alpha-tocopherol content. Our data suggest that there are significant interactions between vitamin E and (n-3) fatty acids that affect the immune system and that further research in this area is warranted.