Decrease in lipid peroxidation measured by breath pentane output in normals after oral supplementation with vitamin E

Effects of Vitamin E and Selenium on Growth Performance, Antioxidant Capacity, and Metabolic Parameters in Growing Furring Blue Foxes (Alopex lagopus)

The objective of this study was to determine whether different dietary vitamin E (VE) and selenium (Se) levels affect the nutrient digestibility, production performance, and antioxidant abilities of growing furring blue foxes. A 4 × 2 factorial arrangement that included 4 levels of VE (0, 100, 200, or 400 mg/kg diet from α-tocopherol acetate) and 2 levels of Se (0 or 0.2 mg/kg diet from glycine selenium) was performed from mid-September to pelting. A metabolism study was conducted for four days starting at the 30th day of the trial. Serum samples were collected at the last day of the study. The results showed that supplementation of growing furring blue fox diets with VE and Se significantly affected the average daily gain (ADG), average daily feed intake, and feed conversion ratio (F:G) (P < 0.05). Dietary Se supplementation enhanced protein and fat digestibility of male blue foxes. There were significant effects of different VE and Se levels in diets on serum antioxidant parameters and metabolic parameters of blue foxes (P < 0.05). In conclusion, this research indicated that dietary supplementation with VE improved ADG and F:G of blue foxes. Addition of VE and Se to blue fox diets increased the antioxidant capacity of blue foxes. The diet with high VE and Se supplementation reduced glucose and triglycerides concentrations in serum. The present study found that growing furring blue foxes had increased growth performance and antioxidant abilities when fed diets with 200 mg VE/kg and nearly 0.1 mg Se/kg.

Preventive effect of vitamin E on iron-induced oxidative damage in rabbit

Although iron (Fe), plays an important role in different oxidative steps during the metabolism of the human body, it can cause free radical damage. Iron ions seem to play a major role in initiation and promotion reactions of intracellular lipid peroxidation. The aim of this study was to investigate if vitamin E has a protective effect on oxidative changes in erythrocytes induced by Fe treatment. Thirty male New Zealand white rabbits weighing 1400 +/- 50 g were used in the study. The animals were divided into three groups. The first group (n:10) was given 500 mg/kg iron-dextran through intraperitoneal (ip) injection. The second group was given 500 mg/kg iron-dextran+100 mg/kg vitamin E(ip). The third group constituted the control group and received a saline solution injection. The activities of erythrocyte antioxidant enzymes; Superoxide Dismutase (SOD), Glutatione peroxidase (GSH-Px), Catalase (CAT) and Malondialdehyde (MDA) level, an indicator of lipid peroxidation, were determined. Erythrocyte SOD, GSH-Px and CAT activities were decreased and MDA level was increased in iron-dextran treated animals compared to the control group (P < 0.05). The activities of the three antioxidant enzymes were increased and MDA level was decreased in iron-dextran and vitamin E treated group compared to the control group (P < 0.05). Our data indicate that lipid peroxidation occurs after iron overload in the blood. In the light of our findings, vitamin E administration can prevent the toxic oxidative effects induced by iron-dependent free radical damage in erythrocytes.

Diagnostic potential of breath analysis--focus on volatile organic compounds

Breath analysis has attracted a considerable amount of scientific and clinical interest during the last decade. In contrast to NO, which is predominantly generated in the bronchial system, volatile organic compounds (VOCs) are mainly blood borne and therefore enable monitoring of different processes in the body. Exhaled ethane and pentane concentrations were elevated in inflammatory diseases. Acetone was linked to dextrose metabolism and lipolysis. Exhaled isoprene concentrations showed correlations with cholesterol biosynthesis. Exhaled levels of sulphur-containing compounds were elevated in liver failure and allograft rejection. Looking at a set of volatile markers may enable recognition and diagnosis of complex diseases such as lung or breast cancer. Due to technical problems of sampling and analysis and a lack of normalization and standardization, huge variations exist between results of different studies. This is among the main reasons why breath analysis could not yet been introduced into clinical practice. This review addresses the basic principles of breath analysis and the diagnostic potential of different volatile breath markers. Analytical procedures, issues concerning biochemistry and exhalation mechanisms of volatile substances, and future developments will be discussed.

Breath analysis in critically ill patients: potential and limitations

Breath tests are attractive since they are noninvasive and can be repeated frequently in the dynamically changing state of critically ill patients. Volatile organic compounds can be produced anywhere in the body and are transported via the bloodstream and exhaled through the lung. They can reflect physiologic or pathologic biochemical processes such as lipid peroxidation, liver disease, renal failure, allograft rejection, and dextrose or cholesterol metabolism. This review describes the diagnostic potential of endogenous organic volatile substances in the breath of critically ill patients. Since many of these patients require ventilatory support, aspects of breath analysis under mechanical ventilation will be addressed. Analytical procedures, problems concerning the physiologic meaning of breath markers and future developments will be discussed.

Plasma levels of vitamin E in Parkinson's disease

Oxidative stress has been implicated as a major contributor to selective neuronal death in Parkinson's disease (PD). Vitamin E is an antioxidant that may protect the brain from free radical-induced oxidative damage. It is, therefore, reasonable to hypothesize that low levels of vitamin E concentrations may increase the risk of developing PD. To elucidate the possible role of vitamin E in the pathogenesis of PD, we assessed the plasma levels of vitamin E, measured by high-performance liquid chromatography (HPLC), in 54 patients with PD. Vitamin E concentrations were also assessed in 93 age and sex matched normal individuals. The mean plasma levels of vitamin E did not differ significantly between these two groups (22.5+/-8.15 &mgr;mol/l for PD patients and 21.0+/-7.9 &mgr;mol/l for controls). The results of our study suggest that plasma vitamin E concentrations do not play a major role in the pathogenesis of PD.

Vitamin E supplementation and endurance exercise: are there benefits?

It has been widely noted that vitamin E shows numerous beneficial effects through and beyond its antioxidative properties; consequently, vitamin E is expected to prevent degenerative diseases. In the field of sports medicine, many studies dealing with vitamin E have been conducted originally from the point of view of its effects on physical performance. Although some earlier studies indicated that vitamin E supplementation could improve physical performance, defects in the study design or statistical analysis were pointed out at a later time. The majority of subsequent well controlled studies have reported no significant effect on physical performance from vitamin E supplementation. Recent studies suggest that endurance exercise may promote free radical generation in the body, and vitamin E may play an important role in preventing the free radical damage associated with endurance exercise. Although there is evidence of free radical involvement in exercise-induced muscle injury, vitamin E supplementation might not be expected to prevent muscle damage caused by exercise in humans without a vitamin E deficiency. Since it is still unclear whether exercise induces lipid peroxidation in the human body, the beneficial effect of vitamin E supplementation on exercise-induced lipid peroxidation has not yet been established. However, it is proposed that as a result of exercise vitamin E may be mobilised from store tissues and redistributed in the body to prevent oxidative damage. Therefore, we are convinced that vitamin E contributes to preventing exercise-induced lipid peroxidation. It has also been indicated that strenuous endurance exercise may enhance the production of oxidised low density lipoprotein (LDL), which plays a key role in the initiation and progression of atherosclerosis. It is also suggested that this enhanced production of oxidised LDL could be reduced if a higher vitamin E status is maintained. Supplementation with 100 to 200mg of vitamin E daily can be recommended for all endurance athletes to prevent exercise-induced oxidative damage and to reap the full health benefits of exercise.

A practical and reliable method for measuring ethane and pentane in expired air from humans

We describe a method for the collection of expired air and further document the performance of our analytical technique that is used to measure ethane and pentane simultaneously. Four minutes of breathing hydrocarbon-free air before collection effectively removed high concentrations of residual ambient ethane and pentane from the lungs, with washout times up to 30 min resulting in no further reductions in breath hydrocarbons. Mean (+/-SE) exhalation rates (pmol/kg b.wt./min) in 11 subjects were 2.4 +/- 0.6 for ethane and 1.5 +/- 1.3 for pentane. Total intraindividual variability in exhalation rates (as percent coefficient of variation, %CV), measured from 4 subjects on at least 6 different days, was greater for pentane (44% CV) than for ethane (29% CV). Analytical variability contributed 6% to the total %CV. Advantages of the method are described, and reasons for the large variability in values reported in the literature are discussed.

Biomarkers of free radical damage applications in experimental animals and in humans

Free radical damage is an important factor in many pathological and toxicological processes. Despite extensive research efforts in biomarkers in recent years, yielding promising results in experimental animals, there is still a great need for additional research on the applicability of, especially non-invasive, biomarkers of free radical damage in humans. This review gives an overview of the applications in experimental and human situations of four main groups of products resulting from free radical damage, these include: lipid peroxidation products, isoprostanes, DNA-hydroxylation products and protein hydroxylation products.

Vitamin E prevents exercise-induced DNA damage

The single cell gel test (SCG test or comet assay) was used to study DNA damage in peripheral white blood cells (WBC) of humans after a single bout of exhaustive exercise and the effect of vitamin supplementation. Human subjects were asked to run on a treadmill until exhaustion and blood samples were taken before and 24 h after the run. A clear increase in DNA strand breakage was observed in the 24-h sample of all probands. A short-term application of multivitamin pills or vitamin E (3 x 800 mg) resulted in a significantly smaller increase of DNA effects in WBC of some probands. When the volunteers were given a supplement of vitamin E (1200 mg daily) for 14 days prior to a run, exercise-induced DNA damage was clearly reduced in all probands. In four out of five subjects, vitamin supplementation completely prevented the induction of DNA damage after exhaustive exercise. Intake of vitamin E for 14 days led to a clear increase in vitamin E serum concentrations. Malondialdehyde (MDA), a marker of lipid peroxidation, was measured in the serum of probands in tests with and without vitamin supplementation for 14 days. MDA concentrations were significantly decreased following vitamin E supplementation but not significantly changed 15 min and 24 h after a run. Our results demonstrate that vitamin E prevents exercise-induced DNA damage and indicate that DNA breakage occurs in WBC after exhaustive exercise as a consequence of oxidative stress.

The potential of the hydrocarbon breath test as a measure of lipid peroxidation

The straight chain aliphatic hydrocarbons ethane and pentane have been advocated as noninvasive markers of free-radical induced lipid peroxidation in humans. In in vitro studies, the evolution of ethane and pentane as end products of n-3 and n-6 polyunsaturated fatty acids, respectively, correlates very well with other markers of lipid peroxidation and even seems to be the most sensitive test available. In laboratory animals the use of both hydrocarbons as in vivo markers of lipid peroxidation has been validated extensively. Although there are other possible sources of hydrocarbons in the body, such as protein oxidation and colonic bacterial metabolism, these apparently are of limited importance and do not interfere with the interpretation of the hydrocarbon breath test. The production of hydrocarbons relative to that of other end products of lipid peroxidation depends on variables that are difficult to control, such as the local availability of iron(II) ions and dioxygen. In addition, hydrocarbons are metabolized in the body, which especially influences the excretion of pentane. Because of the extremely low concentrations of ethane and pentane in human breath, which often are not significantly higher than those in ambient air, the hydrocarbon breath test requires a flawless technique regarding such factors as: (1) the preparation of the subject with hydrocarbon-free air to wash out ambient air hydrocarbons from the lungs, (2) the avoidance of ambient air contamination of the breath sample by using appropriate materials for sampling and storing, and (3) the procedures used to concentrate and filter the samples prior to gas chromatographic determination. For the gas chromatographic separation of hydrocarbons, open tubular capillary columns are preferred because of their high resolution capacity. Only in those settings where expired hydrocarbon levels are substantially higher than ambient air levels might washout prove to be unnecessary, at least in adults. Although many investigators have concentrated on one marker, it seems preferable to measure both ethane and pentane concurrently. The results of the hydrocarbon breath test are not influenced by prior food consumption, but both vitamin E and beta-carotene supplementation decrease hydrocarbon excretion. Nevertheless, the long-term use of a diet high in polyunsaturated fatty acids, such as in parenteral nutrition regimens, may result in increased hydrocarbon exhalation. Hydrocarbon excretion slightly increases with increasing age. Short-term increases follow physical and intellectual stress and exposure to hyperbaric dioxygen.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of alpha-tocopherol on lipid peroxidation and antioxidant system in fibrosarcoma bearing rats

The anticarcinogenic activity of alpha-tocopherol (Vitamin E) was tried in fibrosarcoma induced rats through its antioxidative potential. The rate of formation of malondialdehyde (MDA), the end product of lipid peroxidation was analysed in alpha-tocopherol (400 mg/kg body weight) treated and untreated fibrosarcoma bearing rats with respective controls. The levels of non-enzymic antioxidants like, glutathione and vitamin E, and enzymic antioxidants viz., catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and glutathione-S-transferase (GST) were assayed as well. Significantly increased (p < 0.001) level of lipid peroxide was observed with concomitant decreases in the level of enzymic and non-enzymic antioxidants in fibrosarcoma bearing rats when compared with control animals. In alpha-tocopherol supplemented animals, the corrected level of these parameters were observed likely to near normal values. Thus, alpha-tocopherol can be accepted to pose first line of defense mechanism against excessively formed reactive species due to impaired antioxidant systems in fibrosarcoma conditions, that cause membrane damage leading to deleterious effects.

Pulmonary pentane excretion increases with age in healthy subjects

Excessive lipid peroxidation occurs in various diseases. However, even in health low levels of lipid peroxidation can be detected by measuring the pulmonary excretion of pentane. Lipid peroxidation has been postulated to be one of the causes of the ageing process. In order to test whether pentane excretion is related to age, we measured breath pentane in 47 healthy subjects (ages 21-79). We also measured serum levels of the antioxidants tocopherol, retinol, lycopene, beta carotene, ascorbate and zinc. We found that pentane excretion significantly (P < 0.05, r = 0.32) increased with age. Of the six antioxidants measured, only lycopene decreased significantly (P < 0.05, r = -0.47) with age, however, this decline did not statistically correlate with pentane excretion. The remaining five antioxidants either remained stable or increased over the age range studied. We conclude that lipid peroxidation, as assessed by pentane excretion, increases with advancing age but that this increase is independent of dietary antioxidant levels.

Beta-carotene decreases markers of lipid peroxidation in healthy volunteers

We previously showed that daily intake of beta-carotene, a nontoxic antioxidant, reduces lipid peroxidation as assessed by serum lipid peroxide levels. An alternative method to detect lipid peroxidation is the measurement of pentane in breath. Pentane is a five-carbon hydrocarbon that is released when an omega-6 unsaturated fatty acid undergoes peroxidation. The aim of this study was to see whether graded doses of beta-carotene would affect breath pentane excretion in normal subjects placed on a carotenoid-free liquid diet for two weeks. The subjects were then repleted with either 15 (n = 7) or 120 mg (n = 8) of beta-carotene daily for four weeks while continuing the same diet. Serum beta-carotene and breath pentane were measured before and after beta-carotene refeeding. Lipid peroxidation, as assessed by gas-chromatographic measurement of breath pentane, was significantly (p < 0.05) reduced by daily supplements of 120 mg beta-carotene (from 3.7 +/- 0.9 to 2.2 +/- 1.4 nmol/l). However, the decline in pentane exhalation observed with the 15-mg beta-carotene dose did not achieve statistical significance (p = 0.13).

Oral diet does not alter pulmonary pentane or ethane excretion in healthy subjects

Ethane and pentane are alkanes that are excreted through the lungs to a small degree in healthy subjects. These gasses are produced from the peroxidation of unsaturated fats which are found both in body tissues and in foods. These gasses are excreted in larger amounts by patients with increased production of reactive oxygen metabolites, including those with inflammation or ischemia. Thus, detection of these gasses in excessive quantities is considered evidence for lipid peroxidation. However, the effects of dietary factors on these measurements have not been defined. To define the effects of eating on the pulmonary excretion of these alkanes, 29 healthy subjects were fed a standardized liquid diet (1060 kcal, 12.9 g linoleic acid and 385 mg linolenic acid) after an overnight fast. Breath alkanes were measured at 0, 1, 3, and 6 hours. All subjects had normal vitamin E (1.11 + 0.26 mg/dl), retinol (64 +/- 14 micrograms/dl), beta carotene (27 +/- 21 micrograms/dl), lycopene (23 +/- 12 micrograms/dl) and zinc (81.9 +/- 13.5 micrograms/dl) levels. No statistically significant changes in either alkane were noted relative to the fasting level. We conclude that oral diet does not alter pulmonary ethane or pentane excretion in healthy subjects.

Monitoring of oxidative free radical damage in vivo: analytical aspects

Free radical damage is an important factor in many pathological and toxicological processes. During the last decade a wide range of methods has been developed to determine free radical damage in various biological fluids and at various stages of development. This review offers an overview of the state of the art of monitoring free radical damage in vivo, with special emphasis on the analytical aspects of non-invasive methods.

Vitamin E suppresses increased lipid peroxidation in cigarette smokers

Cigarette smoke contains many xenobiotics, including oxidants and free radicals, which can increase lipid peroxidation. Recently, breath pentane output (BPO) has been recognized as a good indicator of lipid peroxidation. Vitamin E is known to be a potent free radical scavenger which can protect biological membranes against oxidative damage. We investigated the effect of vitamin E (dl-alpha-tocopherol) on lipid peroxidation in 13 healthy smokers. The results showed (1) smokers had increased BPO as compared with 19 healthy non-smokers (16.3 +/- 1.9 vs 5.8 +/- 0.5, pmol/kg body weight/min, p less than 0.001) although both groups had comparable plasma vitamin E and selenium concentrations, (2) supplementation with vitamin E (800 mg/day for 2 weeks) decreased BPO in smokers, and (3) the concentration of plasma selenium-dependent glutathione peroxidase was restored to normal in those smokers (five out of 13) in whom this was low initially. We conclude that a normal plasma concentration of vitamin E does not prevent this increase of lipid peroxidation in smokers but that substantial doses of vitamin E will significantly reduce this increased lipid peroxidation. If a major function of vitamin E is to protect lipids from peroxidation, then smokers have a conditioned insufficiency of vitamin E on a normal diet.