Serum Alpha-tocopherol Research Articles

Serum retinol, beta-carotene, alpha-tocopherol and cholesterol in healthy French children.

Age- and sex-specific reference intervals of data derived from a healthy paediatric population are presented for retinol, beta-carotene, alpha-tocopherol, cholesterol and related proteins in serum. Age was an important covariate for the micronutrient concentration values. Retinol was highly correlated with alpha-tocopherol and cholesterol. Strong correlation was found with both beta-carotene and cholesterol. Serum levels were considered for their appropriateness as indicators of micronutrient status.

Serum α-tocopherol concentration in sheep after intramuscular injection of DL-α-tocopherol

Forty-three crossbred wethers weighing 35 to 60 kg were used to investigate the effect of a single i.m. injection of DL-alpha-tocopherol (DL-alpha-ol). Animals were offered 1 kg/d of a basal diet containing 25 ppm of vitamin E. Lambs were randomly assigned to one of five DL-alpha-ol injection treatments as follows: 1) control (placebo, 0 IU), 2) 125 IU, 3) 250 IU, 4) 500 IU, or 5) 1,000 IU. Blood samples were taken via jugular venipuncture on d 1 before treatment administration and thereafter at designated intervals up to 360 h postinjection. The i.m. injections of DL-alpha-ol irrespective of dose increased serum alpha-tocopherol. Results showed a dose x time interaction (P less than .0001) across all treatments. Serum alpha-tocopherol increased rapidly to maximum concentration during the first 8 to 12 h for all non-zero treatments, followed by a rapid decline to pretreatment values. The mean serum alpha-tocopherol concentration at 0 h was .69 microgram/mL. Estimated peak serum alpha-tocopherol concentrations +/- SE were 6.68 +/- 1.04, 9.62 +/- 1.04, 21.66 +/- 2.37, and 50.75 +/- 7.05 micrograms/mL for Treatments 2 through 5, respectively. Results showed a quadratic dose effect (P less than .0003) on maximum response with apparently no effect on time taken to reach this peak. There was also a quadratic dose effect (P less than .0001) on the area under the concentration-time curve. The time taken for serum alpha-tocopherol to return to pretreatment levels increased with dose (56, 64, 67, and 74 h, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Bioavailability of vitamin E compounds in lambs.

A study was carried out to assess the bioavailabilities of several forms of vitamin E in lambs. A total of 40 lambs was allotted to eight dietary groups of five each and supplemented or not daily for 60 d with equimolar amounts of different vitamin E compounds as follows: 1) control, no supplemental vitamin E, 2) DL-alpha-tocopheryl acetate, 3) D-alpha-tocopheryl acetate, 4), D-alpha-tocopheryl succinate, 5) D-alpha-tocopheryl polyethylene glycol 1,000 succinate (TPGS), 6) DL-alpha-tocopheryl nicotinate, 7) DL-alpha-tocopheryl nicotinate+ TPGS, or 8) D-alpha-tocopheryl acetate + TPGS. During these 60 d, serum alpha-tocopherol concentrations in the control lambs remained constant and lower (P less than .05) than in lambs that received all treatments. Various indices of bioavailability, including Cmax-C(i) (concentration maximum-concentration initial), Ct-C(i) (concentration terminal-concentration initial), areas under the serum concentrations profiles, and pooled increment were higher (P less than .05) with D-alpha-tocopheryl acetate+ TPGS than in the other groups, suggesting a synergism between these forms. No such effect was observed between nicotinate and TPGS. For the TPGS, a water-soluble form of vitamin E, the indices of bioavailability were lower (P less than .05) than for the other groups. D-alpha-tocopheryl acetate resulted in a bioavailability that outranked all the other forms of vitamin E, except those of D-alpha-tocopheryl acetate + TPGS. A slightly higher bioavailability index was observed for D-alpha-tocopheryl succinate than for DL-alpha-tocopheryl nicotinate.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum alpha-tocopherol concentration in relation to subsequent colorectal cancer: pooled data from five cohorts.

Vitamin E is an antioxidant that inhibits mutagenesis and cell transformation. Previous findings in five prospective epidemiologic studies suggested that the level of serum alpha-tocopherol, the predominant form of vitamin E in the blood, was lower in subjects who subsequently developed colorectal cancer than in control subjects. However, the difference was neither obvious nor statistically significant in any one of these five studies. To evaluate in greater detail the association between serum alpha-tocopherol concentration and risk of colorectal cancer, we pooled and analyzed the original data from the five studies. Our analyses were designed to (a) test the hypothesis with greater statistical power, (b) examine the association after adjustment for serum cholesterol levels, and (c) evaluate the association after uniform exclusion of cases diagnosed shortly after blood specimens were drawn. Data for individual subjects were analyzed. To make the design of the component investigations uniformly nested case-control studies with individual matching, we matched controls to cases in two of the cohorts. Subjects were categorized according to study-specific quartile of serum alpha-tocopherol level within the study. The pooled analysis included 289 cases of colorectal cancer and 1267 matched controls. For cancers of the colon and rectum combined, the matched odds ratio (OR) for the highest quartile of serum alpha-tocopherol concentration compared with the lowest was 0.6 (95% confidence interval [CI] = 0.4-1.0). Adjustment for serum cholesterol level attenuated the OR to 0.7 (95% CI = 0.4-1.1). The results suggest that serum alpha-tocopherol concentration may be inversely related to risk of colorectal cancer. It is unclear whether an association exists, however, because the association between serum alpha-tocopherol level and decreased risk of colorectal cancer was modest, the CIs were wide, and, overall, the tests for trend in effect were not significant. Larger observational studies with concurrent dietary data are needed to determine whether vitamin E has a modest but potentially important protective effect against colorectal cancer.

026 Determination of histamine in food by combined ion-pair extraction and reversed-phase HPLC with fluorescence detection

The limit of detection for the described method using UV detection is 5 ng. An increased sensitivity is obtained with fluorescence detection with a detection limit of 1 ng. The linearity and sample recovery were tested by using spiked serum samples. The linearity of the method was confirmed in the range of 0 4 5 gg/ ml for standards and 0 30 gg/ml for serum. The recovery was between 90 and 100%. To determine the within-day and dayto-day precision of this method we used serum pools within and out of the reference area ( 5 20 gg/ml, 11 .6 46.4 gmol/l). For UV detection the coefficient of variation within-day (n = I 0) was between 1.I and 1.9% for the standards and 1.2 and 2.2% for the serum pools. The day-to-day (n = 10) coefficient of variation was 1.4 to 2.4% for the standards and 4.1 to 4.8% for the samples. For fluorescence detection the coefficient of variation within-day (n = 10) was between 0.3 and 0.7% for the standards and 0.3 and 0.9% for the serum samples. The day-to-day coefficient of variation ( n = 10) was 0.5 to 0.9% for the standards and 1.1 to 1.5% for the serum pools. Typical chromatograms are shown in Fig. 1. The presented method allows a routine determination of alpha-tocopherol in serum with UV detection. Using fluorescence detection it may be proposed as a candidate reference method.

025 An HPLC method for the determination of vitamin E (alpha tocopherol) in serum

025 An HPLC method for the determination of vitamin E (alpha tocopherol) in serum

REDUCED CONCENTRATION OF HEPATIC α-TOCOPHEROL IN PATIENTS WITH ALCOHOLIC LIVER CIRRHOSIS

The concentration of alpha-tocopherol was measured in liver biopsy specimens obtained from 83 patients with alcoholic and non-alcoholic liver diseases. The mean hepatic vitamin E content (as alpha-tocopherol) was significantly lower in 23 patients with alcoholic cirrhosis (17.6 +/- 12.1 nmol/mg wet weight liver), compared with 12 patients with normal liver histology (39.2 +/- 29.7 nmol/mg, P less than 0.01). The mean serum concentration of alpha-tocopherol was lower in patients with alcoholic cirrhosis (13.9 +/- 7.0 mumol/l) than in individuals with alcoholic fatty liver (21.3 +/- 9.3 mumol/l, P less than 0.01) and patients with normal liver histology (23.4 +/- 11.6 mumol/l, P less than 0.01). A decreased ratio of serum alpha-tocopherol/total serum lipids was also observed in patients with alcoholic cirrhosis, compared with patients with normal liver histology (P less than 0.05). There was a significant correlation between concentrations of alpha-tocopherol in liver and serum (r = 0.43, P less than 0.001). Furthermore, serum alpha-tocopherol correlated with retinol (r = 0.53, P less than 0.001), selenium (r = 0.45, P less than 0.001), and albumin (r = 0.37, P less than 0.001) in serum. We suggest that the reduced content of hepatic alpha-tocopherol observed in some patients may play a role in ethanol-induced lipid peroxidation.

Hyperbilirubinemia after esophagectomy. A possible role of lipid peroxidation.

Postoperative hyperbilirubinemia was investigated in 18 patients who underwent a single-staged esophagectomy and reconstruction. The total serum bilirubin (TSB) concentration increased progressively after surgery without any evidence of sepsis and reached a peak on day 5 from 0.5 +/- 0.1 to 2.4 +/- 0.4 mg/dl (p less than 0.01), and then decreased by day 14. The TSB concentration rose above 2.5 mg/dl on days 5 or 7 in 8 patients (44%). Alkaline phosphatase and SGOT showed a mild increase during the postoperative period. The increase in the serum lipid peroxide (LPO) concentration, which was measured as malondialdehyde, after surgery correlated closely with the change in the TSB concentration. The LPO concentration was significantly elevated only in the patients with postoperative hyperbilirubinemia, and showed a correlation with the TSB concentration (r = 0.81, p less than 0.01). The level of serum alpha-tocopherol decreased after surgery, but did not differ between the patients with or without postoperative hyperbilirubinemia. These results suggest that lipid peroxidation reactions play a role in the development of hyperbilirubinemia after esophagectomy, which may be due to benign intrahepatic cholestasis.

Serum Micronutrients and Risk of Cancers of Low Incidence in Finland

The associations between serum alpha-tocopherol, beta-carotene, retinol, retinol-binding protein, and selenium levels and the subsequent occurrence of different cancers of low incidence were investigated in a nested case-control study of 39,268 men and women participating in the Social Insurance Institution's Mobile Clinic Health Examination Survey in Finland. During follow-up from the baseline in 1968-1972 to the end of 1977, a total of 115 cancers of the lip, oral cavity, pharynx, larynx, esophagus, liver, gallbladder, kidney, urinary bladder, brain, and skin were reported to the nationwide Finnish Cancer Registry. Alpha-tocopherol, beta-carotene, retinol, retinol-binding protein, and selenium concentrations were determined from stored serum samples collected from these cancer cases and matched controls at baseline. Several sites indicated an elevated risk of cancer at low levels of the serum variables, although only a few of these associations were statistically significant. Only melanoma patients had significantly lower serum alpha-tocopherol and beta-carotene levels than corresponding controls. Since the numbers of cancer cases were small, no firm conclusions can be drawn from these results until they have been confirmed in studies based on larger cohorts or on pooled data from several small samples.

A Randomized Trial of Replacement Antioxidant Vitamin Therapy for Neutrophil Locomotory Dysfunction in Blunt Trauma

Studies in patients with serious trauma indicate that the observed neutrophil (PMN) locomotory dysfunction is partly the result of auto-oxidation as shown by evidence of preactivation, diminished reducing capacity, and low serum and cellular ascorbic acid and alpha-tocopherol. To investigate whether replacement of the antioxidant vitamins ascorbic acid and alpha-tocopherol can improve the PMN locomotory defect, ascorbic acid, alpha-tocopherol, ascorbic acid and alpha-tocopherol, or placebo was administered to a total of 46 victims of blunt trauma. PMN locomotion was quantitated using a micropore filter assay. Locomotion data were analyzed by repeated measures analysis with a split plot design and data for days 2-6 after injury were compared. Compared with placebo, the antioxidants improved PMN locomotion. The mean differences in distance migrated (treated minus placebo) were ascorbic acid and alpha-tocopherol = 11.3 +/- 3.0 microns (one-tailed p = 0.001) (mean +/- SE); ascorbic acid = 4.7 +/- 3.4 microns (p = 0.19); and alpha-tocopherol = 3.3 +/- 2.9 microns (p = 0.27). Although both antioxidants given together produced the best results, a plot of the 95% confidence intervals indicates that ascorbic acid and alpha-tocopherol, either given alone, were also better than placebo. We conclude that antioxidant replacement therapy significantly improves the PMN locomotory abnormality in blunt trauma.

Assessment of the influence of dietary vitamin E on sows and offspring in three parities: reproductive performance, tissue tocopherol, and effects on progeny

Sixty crossbred (Yorkshire-Hampshire X Duroc) gilts were fed one of four corn-soybean meal diets fortified with .3 ppm Se and 0, 16, 33, or 66 IU of DL-alpha-tocopheryl acetate/kg. The study was conducted over a three-parity period to evaluate sow reproductive performance and the vitamin E tissue status of both sows and progeny at various time periods postcoitum and(or) postpartum. The basal diet averaged 8.4 mg of alpha-tocopherol/kg and .38 ppm of Se. Although litter size at birth was lowest (P less than .15) when sows were fed the basal diet, a higher incidence of agalactia when sows were fed the lower dietary vitamin E levels resulted in an increased (P less than .05) litter size at 7 d postpartum as dietary vitamin E increased. Sow serum alpha-tocopherol increased (P less than .01) at each measurement period as dietary vitamin E level increased. Colostrum and milk alpha-tocopherol concentrations increased (P less than .01) as dietary vitamin E level increased, and colostrum values were three to five times higher than at later milks. Colostrum alpha-tocopherol declined by parity from sows fed less than or equal to 16 IU/kg but was similar at each parity for sows fed greater than or equal to 33 IU/kg, resulting in a dietary vitamin E x parity interaction (P less than .01). The Se content of sow milk declined with parity but was not affected by dietary vitamin E level. Sow liver tocopherol at weaning (28 d postpartum) increased (P less than .01) as dietary vitamin E increased and increased with parity (P less than .05). Pig serum and liver alpha-tocopherol concentrations were elevated at birth and 7 and 28 d of age as sow dietary level of vitamin E increased. Upon weaning, pigs were fed a torula yeast-dextrose diet that contained 3.0 mg of alpha-tocopherol/kg and .32 ppm Se for a 28-d postweaning period. Liver and serum alpha-tocopherol concentrations declined during the postweaning period. Evidence of the vitamin E deficiency occurred at 28 d postweaning in the progeny from sows fed the basal diet or 16 IU of vitamin E; the incidence was more prevalent in the pigs from Parities II and III. These results suggest that a supplemental level of 16 IU of vitamin E/kg of diet was inadequate for the reproducing sow; higher levels are justified, particularly when females are retained in the herd for several parities.

Additional evidence of autoxidation as a possible mechanism of neutrophil locomotory dysfunction in blunt trauma

Previous studies in victims of blunt injury suggest that the observed neutrophil (PMN) locomotory dysfunction is, in part, due to autoxidation. To further clarify the occurrence and significance of autoxidation, we studied changes in levels of glutathione in PMN and of ascorbic acid and alpha-tocopherol in serum and blood cells of postsurgical and blunt trauma patients. Levels of total, reduced, and oxidized glutathione in PMN from trauma patients were similar to normal controls. Serum and cellular ascorbic acid and alpha-tocopherol levels dropped significantly after injury and remained below normal control levels during the 7 to 8-day study period. Low serum alpha-tocopherol was partially explainable on the basis of changes in serum lipids. When serum samples of trauma patients were thawed unprotected without pyrogallol, there was significant loss of recoverable alpha-tocopherol, whereas no significant losses occurred with unprotected thawed normal sera. Less total reducing capacity was observed in PMN of trauma patients compared with normal controls. These findings indicate that synthesis and regeneration capacity of glutathione are intact but that the levels of the consumable antioxidants, ascorbic acid, and alpha-tocopherol are compromised after injury. These results add further support to the hypothesis that autoxidation occurs in trauma.

Effect of vitamin E, phosphorus and sorbitol on growth performance and serum and tissue cholesterol concentrations in the pig.

A total of 180 crossbred, weanling pigs were assigned to five dietary treatment groups: 1) a basal corn-soybean meal diet formulated to current NRC recommendations, 2) basal + monosodium phosphate (2 x NRC P recommendations; P), 3) basal + alpha-tocopheryl acetate (220 IU/kg; E), 4) basal + sorbitol (1% of the diet; S) and 5) basal + PES. Dietary treatments were continued until market weight (104 kg). Blood samples were obtained at 3-wk intervals for analysis of serum alpha-tocopherol, P and total cholesterol. Liver and muscle (semimembranosus) samples were obtained at the end of the starter, grower and finisher phases for determination of total cholesterol concentration. The Ca:P imbalance produced by the high-phosphorus diets (P and PES) increased feed intake during the finisher phase. Dietary treatment did not consistently affect total serum cholesterol at any phase of growth. A transient 21.5% (P less than .05) depression of liver cholesterol concentration was observed in the PES-fed pigs at the end of the starter phase but was not apparent at market weight. A similar trend (nonsignificant) was noted for muscle cholesterol concentration. The present study suggests that the PES diet can decrease tissue cholesterol concentration during the nursery phase, but it remains uncertain whether this transient response is a function of age and(or) diet transition at weaning. Further research is necessary to determine whether this response can be translated to the finishing phase, and thereby reduce carcass cholesterol.

Fat-soluble-vitamin status during the first year of life in infants with cystic fibrosis identified by screening of newborns

We investigated the fat-soluble-vitamin status during the first year of life in 36 infants with cystic fibrosis (CF) consecutively identified by screening of newborns. At initial evaluation (at age 51.0 +/- 26.7 d) 36% of patients were hypoalbuminemic, 21% had low serum retinol, 35% had low serum 25-hydroxyvitamin D. 38% had low serum alpha-tocopherol and low ratios of serum vitamin E to total lipids, and none had elevated protein in vitamin K absence (PIVKA). Hypoalbuminemia was more common in breast-fed than in formula-fed infants. Seventy-two-hour fecal fat excretion correlated inversely with serum alpha-tocopherol. Treatment with oral pancreatic enzyme supplements, a multiple vitamin, and additional vitamin E was associated with normalization of serum albumin, retinol, and 25-hydroxyvitamin D and negative PIVKA at age 6 and 12 mo. Approximately 10% of patients remained vitamin E deficient. Biochemical evidence of fat-soluble-vitamin deficiencies is common before age 3 mo in patients with CF and, except for vitamin E, these deficiencies corrected with standard therapy.

Serum alpha-tocopherol levels of Mexican Americans, Cubans, and Puerto Ricans aged 4–74 y

Data from the Hispanic Health and Nutrition Examination Survey were used to examine serum alpha-tocopherol levels (in subjects aged 4-74 y) and ratios of alpha-tocopherol to cholesterol plus triglyceride and to cholesterol (in subjects aged 20-74 y) of Mexican Americans (MA), Cubans, and Puerto Ricans (PR). Neither alpha-tocopherol nor the alpha-tocopherol-lipid ratios differed between sexes. PR had lower mean alpha-tocopherol and alpha-tocopherol-lipid ratios and higher prevalences of alpha-tocopherol less than 11.6 mumol/L than did MA or Cubans in several age groups. MA and Cuban adolescents had lower alpha-tocopherol levels than children had. Mean alpha-tocopherol levels and alpha-tocopherol-lipid ratios increased and prevalences of alpha-tocopherol less than 11.6 mumol/L decreased during adulthood in all three ethnic groups.

Maternal and Fetal Vitamin E Concentrations and Selenium-Vitamin E Interrelationships in Dairy Cattle

Paired dam-fetus liver and serum samples were collected from 101 pregnant dairy cattle at slaughter to determine mean fetal and maternal liver and serum vitamin E concentrations, relationships between maternal and fetal vitamin E status and interrelationships between selenium and vitamin E status. Fetal age was estimated from fetal crown-to-rump length. Fetal alpha-tocopherol concentration ranged from 0 to 31.4 micrograms/g dry wt with a mean of 7.1 micrograms/g dry wt and from 0 to 0.92 micrograms/ml with a mean of 0.29 micrograms/ml for liver and serum, respectively. Mean maternal liver (12.5 micrograms/g dry wt) and serum (2.16 micrograms/ml) alpha-tocopherol concentrations and vitamin E to cholesterol ratio (1.45) were 1.8, 7.4 and 3.5 times greater (P less than 0.0001) than fetal means, indicating limited placental transfer of vitamin E to the fetus. Gestational age had no effect on maternal vitamin E concentration, however, fetal tissue alpha-tocopherol concentration declined (P less than 0.05) with fetal age. Maternal serum alpha-tocopherol concentration and fetal age were found to best predict fetal alpha-tocopherol concentration in serum. Interrelationships between selenium and vitamin E status were minimal. These data suggest inefficient placental transfer of vitamin E, resulting in minimal protection of the neonate from vitamin E-deficiency disease as a result of prepartal maternal supplementation.

Alpha- and gamma-tocopherol levels in lipoproteins fractionated by affinity chromatography.

Alpha- and gamma-tocopherol levels of nine women were measured in whole serum and in serum lipoproteins separated by heparin affinity chromatography. Alpha-tocopherol levels (mean +/- SD) in whole serum, low density plus very low density lipoproteins and high density lipoproteins were 10.8 +/- 2.7, 6.4 +/- 1.6 and 4.6 +/- 1.4 (micrograms/ml), respectively. Corresponding values (micrograms/ml) for gamma-tocopherol were 1.2 +/- 0.5, 0.7 +/- 0.3 and 0.6 +/- 0.2. Recoveries of serum alpha- and gamma-tocopherol from the heparin columns were 102 +/- 5% and 105 +/- 7%, respectively. Serum alpha-tocopherol was linearly correlated with components of high density lipoprotein (apolipoproteins, high density lipoprotein cholesterol), but not with serum total lipids or indices of low density lipoprotein, even though high density lipoprotein carried less than half of the serum alpha-tocopherol. However, serum gamma-tocopherol was highly correlated with indices of serum lipids, such as serum cholesterol (r = 0.92, p = 0.005). The coefficient for the correlation of low density lipoprotein (+ very low density lipoprotein) tocopherol with high density lipoprotein tocopherol was r = 0.66 (p = 0.06) for alpha-tocopherol and r = 0.84 (p = 0.004) for gamma-tocopherol. These differences in the relationships of the two tocopherols to lipids and lipoproteins support the view that when the two tocopherols are present at normal dietary levels, gamma-tocopherol partitions between lipoproteins based on their relative lipid content, but a portion of the alpha-tocopherol in high density lipoprotein is specifically bound.

Role of Lipid Peroxidation and Oxygen Radicals in Compound 48/80-Induced Gastric Mucosal Injury in Rats

Repeated administration of a small dose of compound 48/80 induced acute gastric mucosal injury in rats. Thiobarbituric acid (TBA) reactants in the gastric mucosa were significantly increased and serum alpha-tocopherol was significantly decreased after the treatment. The total area of gastric lesions and the increase in TBA reactants in the gastric mucosa were significantly reduced by pretreatment with superoxide dismutase (SOD) and/or catalase, allopurinol and anti-rat polymorphonuclear leukocytes (PMN) antibody. Lipid peroxidation and oxygen radicals derived from both the xanthine-xanthine oxidase system and PMN may be involved in the pathogenesis of compound 48/80-induced gastric mucosal injury.

Book Reviews

Journal Article Book Reviews Get access Serum Alpha-Tocopherol and the Risk of Cancer. P. Knekt, Finland, Social Insurance Institution, 1988, pp 148, ML:83. F GERRARD F GERRARD Search for other works by this author on: Oxford Academic PubMed Google Scholar International Journal of Epidemiology, Volume 18, Issue 4, December 1989, Page 1001, https://doi.org/10.1093/ije/18.4.1001 Published: 01 December 1989

Changes in distribution of .ALPHA.-tocopherol and cholesterol in serum lipoproteins and tissues of rats by dietary PCB and dietary level of protein.

An experiment was conducted with growing rats to examine the influence of dietary addition of 0.1% polychlorinated biphenyls (PCB) and dietary level of protein on the distributions of alpha-tocopherol and cholesterol in serum lipoproteins and tissues. Addition of PCB increased serum alpha-tocopherol. This was mainly due to the increment in the fractions of chylomicrons/very-low-density lipoproteins (VLDL) and high-density lipoproteins (HDL). This chemical also increased serum cholesterol and HDL cholesterol. The contents of alpha-tocopherol and cholesterol in HDL fraction were higher in the high protein groups as compared to the low protein groups, regardless of PCB intake. PCB intake increased the concentrations of alpha-tocopherol in tissues including spleen, lung, kidney, testis, muscle, adipose tissue, and brain. High protein diet increased the levels of alpha-tocopherol in these tissues as compared to low protein diet. PCB intake also increased adrenal alpha-tocopherol, which was potentiated with low protein diet. The increment in liver alpha-tocopherol by PCB intake was observed only in the animals fed on low protein diet.