Hum. Reprod. Advance Access published online on June 20, 2007
Human Reproduction, doi:10.1093/humrep/dem146
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Effect of different contraceptive methods on the oxidative stress status in women aged 40–48 years from the ELAN study in the province of Liège, Belgium
1 Department of Cardiovascular Surgery, University of Liège, CHU Sart Tilman, 4000 Liège, Belgium 2 Research Centre for Experimental Surgery (CREDEC), University of Liège, CHU Sart Tilman, 4000 Liège, Belgium 3 Department of Medical Informatics and Biostatistics, University of Liège, CHU Sart Tilman, 4000 Liège, Belgium 4 Department of Gynaecology, University of Liège, CHU Sart Tilman, 4000 Liège, Belgium 5 Department of General Medicine, University of Liège, CHU Sart Tilman, 4000 Liège, Belgium 6 Laboratory of Clinical Biology, University of Liège, CHU Sart Tilman, 4000 Liège, Belgium 7 Department of Toxicology, University of Liège, CHU Sart Tilman, 4000 Liège, Belgium
8 Correspondence address. E-mail: j.pincemail{at}chu.ulg.ac.be
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Abstract |
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 Top Abstract IntroductionMaterial and MethodsResultsDiscussionConclusionsAuthorship and ContributorshipAcknowledgementsReferences |
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BACKGROUND: Oxidative stress is associated with the development of several disorders including cardiovascular disease and cancer. Among conditions known to influence oxidative stress, the use of oral contraception (OC) in women has been a matter of ongoing discussion.
METHODS: A total of 897 eligible and healthy volunteers were recruited from among the patients of 50 general practitioners participating in the ELAN study (Etude Liégeoise sur les ANtioxydants). A subsample consisting of 209 women aged 40–48 years was studied for a comprehensive oxidative stress status (OSS), including the analysis of antioxidants, trace elements and three markers of oxidative damage to lipids. Among 209 subsample, 49 (23%) were OC users (OCU), 119 (57%) non-contraception users (NCU) and 41 (20%) were intrauterine (hormonal and copper) devices users (IUD).
RESULTS: After adjustment for smoking, systolic and diastolic blood pressure and BMI (or waist circumference), a marked and significant increase in lipid peroxides was observed among OCU women when compared with NCU and IUD users. A cut-off value of 660 µM in lipid peroxides allowed the discrimination of OCU from the two other groups. In contrast, no difference was observed in the plasma concentration of both oxidized low-density lipoprotein (LDL) and their related antibodies. The increased level in lipid peroxides was strongly related to higher concentrations of copper (r < 0.84; P < 0.0001, cut-off value 1.2 mg/l). When compared with NCU and IUD users, plasma antioxidant defences were significantly altered in OCU women as shown by lower levels of 
-carotene (decrease of 39%; P < 0.01) and 
-tocopherol (decrease by 22%; P < 0.01). In contrast, higher concentrations of selenium (increased by 11.8%; P < 0.01) were observed in OCU women. Blood concentrations of vitamin C, 
-tocopherol and zinc were unaffected by OC use.
CONCLUSIONS: The intake of OC significantly increases the lipid peroxidation in women aged 40–48 years. This may represent a potential cardiovascular risk factor for these women.
Key words: oxidative stress/antioxidants/oral contraception/ELAN study
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Introduction |
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Oxidative stress is defined as an imbalance between antioxidants and reactive oxygen species (ROS) in favour of the latter. ROS, which include free radicals, are continuously produced in the body and play an important physiological role at low concentrations. They act as second messengers capable of regulating apoptosis, activating transcription factors and modulating the expression of various genes involved in immune response. Various conditions, can, however, lead to a non-physiological production of ROS (sun exposure, intense exercise, smoking habits, chronic inflammation, metal poisoning, mitochondrial dysfunction or hyperglycaemia). Because of due to their high reactivity, ROS will cause irreversible cell lesions through oxidative alterations to lipids, DNA and proteins. Alterations of these structures are suspected to be linked to the development of several human pathologies including atherosclerosis, cardiovascular disease, cancer, diabetes complications, macular degeneration and arthritis. To limit the harmful effects of ROS, a high-performance antioxidant system consisting of enzymes, proteins, vitamins (A, C and E), carotenoids, flavonoids, trace elements and small molecules, such as glutathione, may interact with ROS and regulate their production down to the physiological range. If these antioxidant defences are overwhelmed by excessive ROS production, or not sufficiently provided by diet or supplements, oxidative stress may consequently take place in the body (Cutler, 2005
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Since the discovery that oral progestational 19-nor steroids could inhibit ovulation (Chang et al., 1956), several million women have used different types of synthetic estrogens and progestins to prevent conception. In post-menopausal women, hormone replacement therapy (HRT) is based on the intake of different types of hormones involving estrogens (namely estradiol and conjugated estrogens) and natural progesterone or synthetic progestins in order to replace the failing ovarian secretion.
Ever since the introduction of these drugs, data are scarce about their relationship with oxidative stress and the topic still remains a subject of debate. It has been suggested, but not generally admitted, that estrogens have an antioxidant effect that may contribute to its protective effects on the cardiovascular system through inhibition of lipid oxidation (Brown et al., 2000; Ling et al., 2006). Studies conducted in vitro, but not all (Saha et al., 2000; Chiang et al., 2004), have shown that estrogens, and more particularly estradiol, were able to reduce significantly the oxidative damage to lipids exposed to several free radical generating systems (Sugioka et al., 1987; McManus et al., 1996; Markides et al., 1998; Miura et al., 1998; Mueck et al., 2000; Hwang et al., 2000; Karbownik et al., 2001; Yen et al., 2001). According to Thibodeau et al. (2002), the apparent discrepancy in the data was largely caused by the chemical heterogeneity in the estrogen family and by their concentration and the environment in which they are found.
Most of the in vivo studies performed on rats and women receiving HRT observed an antioxidant effect of estrogen (Clemente et al., 1999; Hernandez et al., 2000; Seeger et al., 2000; Dantas et al., 2002; Telci et al., 2002; Wakatsuki et al., 2003; Ahotupa et al., 2004; Bednarek-Tupikowska et al., 2006; Misra et al., 2006). This was, however, not confirmed in other reports (McManus et al., 1997; Heikkinen et al., 1998; Wen et al., 2000; Bureau et al., 2002; Falkeborn et al., 2002). Surprisingly, only a few studies have investigated the relationship between combined oral contraceptives containing estrogens and progestins, and oxidative stress. Reports from the beginning of the nineties demonstrated a significant increase in blood lipid peroxides (Kose et al., 1993; Sissan et al; 1995) responsible for increased platelet aggregation in rats after oral contraceptive (OC) administration (Ciavatti et al., 1989; Ciavetti and Renaud, 1991). In agreement with other studies (Horwitt et al., 1975; Prasad et al., 1975a; Yeung, 1976; Arab et al., 1982; Palan et al., 1989; Berg et al., 1997a) described a strong decrease in plasma antioxidant -carotene among OC users in bivariate analysis, more particularly among women above the age of 35 years. In contrast, Capel et al. (1981) followed by Massafra et al. (1993) found that a 9-cycle course of a combined oral contraceptive (ethinylestradiol 20 µg and desogestrel 150 µg) in young women led to a significant increased activity of antioxidative enzymes, namely catalase and glutathione peroxidase (GPx).
Recently, a large scale study was conducted by our group to assess the oxidative stress status (OSS) of healthy individuals aged 40–60 years living in the Province of Liege, Belgium. Due to the conflicting data described above, we decided to measure, in a subpopulation of women in the age ranged 40–48 years, the effects of contraceptive methods on parameters of oxidative stress, including antioxidant vitamins, trace elements and markers of oxidative damage to lipids.
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Material and Methods |
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Subjects
The ELAN ("Etude Liégeoise sur les ANtioxydants") study was conducted from March through July 2006 as a joint project between the University of Liège, the University Hospital of Liège and the local health services of the Province of Liège (Belgium). A stratified sample of 55 general practitioners working in the Province was selected as follows: 21 (38%) in urban environment, 15 (27%) in semi urban and 19 (35%) in rural environment. Each physician was asked each to recruit in his/her practice 20 presumably healthy volunteers within the age range of 40–60 years. Exclusion criteria for participating in the study were (i) intake of antioxidant supplementation and (ii) any previous history of cardiovascular diseases, diabetes or cancer. A total of 897 eligible volunteers were finally enrolled in the study: 349 (39%) men and 548 (61%) women. The subsample studied in the present work consisted of 209 women aged 40–48 years: 49 (23%) of these women were OC users (OCU), 119 (57%) non-contraception users (NCU) and 41 were (20%) intrauterine (hormonal and copper) devices users (IUD) (Table 1).
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Clinical examination
Women were asked to attend their physician's office between 8 and 10 a.m. for taking a 35 ml blood sample. Subjects were fasted for at least 12 h and not allowed to drink fruit juice and to perform physical activity the day before the visit. In the same time, information including age, occupation, height, weight, blood pressure, smoking habits, alcohol and drugs consumption, waist circumference and physical activity was collected. The BMI was calculated from height and weight (kg/m2). The study protocol was approved by the University Hospital Ethics Committee for medical research. All contacted volunteers received written information about the goal of the study and signed an informed consent form in case of approval prior to enrollment. All participants completed a home-made food questionnaire for evaluating their daily intake in fruits and vegetables. According to tables of diet composition (Souci et al., 2000
), a score reflecting the daily consumption of both vitamin C and -carotene was established.
Analytical procedures
antioxidant and trace element determination
Blood samples were drawn on EDTA or Na-heparin as anticoagulant or clot activating gel according to the investigated parameter. Blood samples were immediately centrifuged on site and plasma or sera were frozen as aliquots on ice packs coming from a –80°C freezer and placed in a refrigerating box. For vitamin C determination, 0.5 ml plasma was immediately transferred to ice-cold tubes containing 0.5 ml of 10% metaphosphoric acid. The whole mixture was frozen on ice packs. Analyses were performed on the day of blood collection by a spectrophotometric method using the reduction of 2,6-dichlorophenolindophenol (Perkin Elmer Lambda 40 Norwalk, USA) (Omaye et al., 1979) (sensitivity: 2 µg/ml, inter and intra CV: 4 and 6%). Plasma vitamin E ( and -tocopherols) (-tocopherol: sensitivity 0.2 µg/ml, inter and intra CV: 2.93 and 3.53%; -tocopherol: sensitivity 0.24 µg/ml, inter and intra CV: 9.01 and 14.34%) and -carotene (sensitivity 0,022 mg/l, inter and intra CV: 5.35 and 10.73%) were determined simultaneously by HPLC procedure (Alliance Waters, USA) coupled with a diode array detector (PDA 2996, Waters, USA) (Zhao et al., 2004). Blood levels of vitamin E were normalized to a reference lipid, namely cholesterol, which was determined by an enzymatic method with cholesterol oxidase. Thiol proteins were detected according to the Ellman's method (Butterworth et al., 1967) (sensitivity 50 µM, inter and intra assay CV: 10%). The plasma levels of selenium (sensitivity 23.4 µg/l, inter and intra CV: 4.28 and 3.81%), copper (sensitivity 0.12 mg/l, inter and intra assay CV: 3.62 and 5.64%) and zinc (sensitivity 0.10 mg/l, inter and intra CV: 2.74 and 6.51%) were determined by inductively coupled plasma-mass spectroscopy (Sturup et al., 2005). The ratio of vitamin C/-tocopherol was used as a potential risk factor for cardiovascular disease (Gey, 1998). The /-tocopherol ratio was determined as a sensitive index of -tocopherol ingestion (Baker et al., 1986).
markers of lipid peroxidation
The analysis of lipid peroxides as markers of oxidative damage to lipids was performed with the commercial kit (Oxystat, Biomedica Gruppe, Austria). Briefly, the peroxide (-OOH) concentration was determined spectrophotometrically by reaction of the biological peroxides with peroxidase and a subsequent colour reaction using 3,3',5,5'-tetramethylbenzidine as substrate (sensitivity: 11 µM, inter and intra CV: 5.4 and 10%).
Oxidized low-density lipoprotein (LDL) in plasma samples was determined spectrophotometrically with a competitive enzyme-linked immunosorbent assay (ELISA) kit (Immunodiagnostik, Germany) (sensitivity: 9.66 ng/ml, inter and intra CV: 6.17 and 7%). The titre in free antibodies (IgG) against oxidized LDL (Ab-Ox-LDL) was assessed with a commercial enzyme immunoassay (Biomedica Gruppe, Austria) using Cu2+ oxidized LDL as antigen (sensitivity: 37 IU/ml, inter and intra CV: 10.5%).
Statistical analysis
Results were expressed as mean ± standard deviation (SD) for quantitative variables, while frequencies and proportions (%) were used for categorical variables. Mean values were compared by one-way analysis of variance followed by multiple comparisons. Proportions were compared by the chi-squared test for contingency tables. Non-parametric Kruskal–Wallis and Wilcoxon rank sum tests were also used for comparing samples from different groups when normality assumptions could not be fulfilled. Correlation coefficients (classical or non-parametric Spearman's test) were calculated for measuring the association between two quantitative variables. The relationship between biochemical parameters and other variables was assessed by multiple regression analysis, while for binary variables the logistic regression method was used. The latter approach also allows to determination of cut-off points in the covariates. Data were also displayed graphically; in particular probability densities were fitted by a non-parametric fitting method. Calculations were always carried out on the maximum number of data available. Missing data were not replaced. Results were considered to be significant at the 5% critical level (P < 0.05). Data analysis was carried out using SAS (version 9.1 for Windows) and S-Plus (version 9.0) statistical packages.
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Results |
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Effect of the type of contraceptive method on clinical and biochemical parameters
Demographic, biometric and clinical characteristics of the studied population are given in Table 2. The groups differed with respect to smoking. Women in the NCU group presented a higher BMI than those in the IUD group (25.8 ± 5.2 versus 23.1 ± 3.8 kg/m2, P < 0.01). This result was confirmed by the measure of the waist circumference. Patients in the IUD group had a lower systolic blood pressure than those of the other two groups (P < 0.01), while diastolic blood pressure was similar (P = 0.14). For all other variables, the three groups were comparable. With respect to the daily intake of
-carotene, no significant changes were observed between all three groups. Respective scoring for this parameter was 4.7 ± 2.8 mg/day (NCU), 4.9 ± 2.9 mg/day (OCU) and 4.0 ± 2.7 mg/day (IUD). For vitamin C, scoring was as follows: 143.3 ± 75.8 mg/day (NCU), 152.8 ± 61 mg/day (OCU) and 108.7 ± 58.4 mg/day (IUD). Statistical analysis revealed that only IUD scoring was significantly different (P < 0.02) than those of the two other groups.
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As shown in Table 3, the contraceptive groups compared with NCU were similar concerning levels of vitamin C,
-tocopherol, vitamin C/-tocopherol ratio, -tocopherol/cholesterol ratio, zinc, oxidized LDL and Ab-Ox-LDL. From a multivariate point of view, when adjusting the levels of biochemical parameters for smoking, systolic and diastolic blood pressures and BMI (or waist circumference), there was a small though significant effect on the -tocopherol level (P < 0.05) according to the type of contraception, as this level was lower in the OCU and IUD than in the NCU group. This was confirmed on the ratio of -tocopherol/-tocopherol (P < 0.05). Women taking OC, when compared with IUD or NCU, had a significantly lower -carotene level (P < 0.0001) and higher selenium (P < 0.0001), lipid peroxides (P < 0.0001) and copper (P < 0.0001) levels as well as a higher copper/zinc ratio (P < 0.0001). The level of thiol proteins was higher for women with IUD than for women who were NCU or OCU (P < 0.01).
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As shown in Table 3, in the OCU group, the values of copper, the copper/zinc ratio and lipid peroxides reached values that largely exceeded the normal range established for these three parameters (i.e. 0.70–1.40 mg/l, 1.00–1.17 and 48–400 µmol/l for copper, copper/zinc ratio and lipid peroxides, respectively). However, despite modifications, the levels in selenium,
-tocopherol and -carotene remained within the reference values established by the Clinical Laboratories of the University Hospital of Liège. Table 4 compares OSS among women using IUD containing either copper or levonorgestrel. No significant difference could be observed between both groups.
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Prediction of the type of contraception oxidative stress
Figure 1 exhibits a strong, positive correlation (r = 0.84; P < 0.0001) between the concentration of plasma copper and lipid peroxides for all women involved in the ELAN study. Similar findings were observed with the copper/zinc ratio (r = 0.78; P < 0.0001). Statistical analysis allowed us to measure the potential effect of OC on the values of these parameters. Since lipid peroxides and copper levels were similar in the NCU and IUD groups, the two groups were merged (NCU + IUD). As seen in Fig. 2, the concentration of lipid peroxides clearly shifted to high values in OCU when comparison with NCU + IUD. By logistic regression analysis, a plasma level of lipid peroxides of 660 µM yielded sensitivity of 80% (proportion of OCU women with level >660 µM) and a specificity of 84% (proportion of NCU with level <660 µM). Figure 3A and B display the level of plasma copper and the copper/zinc ratio in groups of OCU versus NCU + IUD. For these parameters, the cut-off values were 1.2 mg/l (sensitivity 82%; specificity 85%) and 2.1 (sensitivity 78%; specificity 81%), respectively.
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Discussion |
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TopAbstractIntroductionMaterial and MethodsResultsDiscussionConclusionsAuthorship and ContributorshipAcknowledgementsReferences |
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The initial goal of the ELAN study was to document the OSS of the population living in the Province of Liège, Belgium. To the best of our knowledge, this is the first study performed in this country on such a large scale (897 subjects), using the analysis of 16 parameters including antioxidants, trace elements and markers of lipid peroxidation. The study only addressed men and women aged 40–60 years. This choice was based on the fact that this group is associated with increasing risk for developing several pathologies including cancer and cardiovascular diseases.
Among conditions known to influence OSS, the use of OC in women has been a matter of ongoing discussion. Although this method of contraception is estimated to be used by 50–100 million women worldwide, data about the relationship between steroid contraception and oxidative stress are scarce and, overall, conflicting. As discussed earlier, data obtained from both in vitro and in vivo studies have pointed out pro- and antioxidant properties of estrogens but also an absence of effect. Our study shows that OC significantly alters the OSS of women aged 40–48 years.
Antioxidants
Our data indicate that OC has no effect on the concentration of vitamin C, -tocopherol, vitamin C/-tocopherol ratio, -tocopherol/cholesterol ratio when compared with both NCU and IUD (Table 3). In contrast, our study points to significant disturbances in the level of -carotene in the plasma of women taking contraceptive pills. Our original food frequency questionnaire clearly indicates that such modifications in plasma -carotene cannot be attributed to diet changes between all three groups. From a univariate point of view, the concentration of -carotene in OCU decreased by 
39% (P < 0.01) and 50% (P < 0.001) when compared, respectively, with the groups of NCU and IUD. This is in agreement with the study of Palan et al., (2006), and, more specifically, the study of Berg et al. in 1997 on a sample of 610 women aged between 18 and 44 years. It has been speculated that estrogens induce an activation of the retinol binding protein (Mooij et al., 1991), thus possibly increasing the conversion of -carotene into retinol. Whatever the mechanism, it is important to highlight how this decrease in -carotene concentration must be interpreted in OCU's. The reference values for -carotene (0.08–0.60 mg/l) established in our hospital are in good agreement with those generally listed and admitted in the literature (Galan et al., 2005). With respect to our laboratory values, a woman taking an oral hormonal contraception and having a mean concentration of 0.22 mg/l as shown in our study should be, therefore, considered as belonging to a normal population. In terms of disease prevention, this is, however, not a normal value since various epidemiological studies including the important WHO Monica Vitamin Substudy (Gey, 1994) have clearly determined a cut-off point of 0.215 mg/l associated with an increased risk of developing a cancer or a cardiovascular disease. Using a multivariate analysis, we also observed a cumulative effect of cigarette smoking (another factor of cardiovascular risk) and oral contraceptive usage on the decrease in plasma -carotene (data not shown), which is in agreement with Palan et al., (1989).
Trace elements
Although being in the range of normal reference values, selenium concentration appeared to be significantly higher (11.8%; P < 0.01) in OCU than those of NCU and IUD (Table 2). This could be explained by the fact that the use of combined OC (20 µg ethinylestradiol and 150 µg desogestrel) led to a significant increase of GPx, a seleno-dependent enzyme assuming the elimination of lipid peroxides (Massafra et al., 1993). Such a difference in selenium status could be, however, misinterpreted in our study since plasma selenium (as well GPx activity) in women of reproductive age were fluctuating in synchrony with variations in circulating estrogen concentrations. Indeed, Ha and Smith (2003) demonstrated that selenium level were significantly greater during the periovulatory phase by 14.2 and 11.3% than during the early follicular and mid-luteal phases, respectively. Interestingly, the peak of selenium concentrations strictly coincided with those of 17--estradiol (P < 0.0001). In the current study, we had no information at which phase blood sampling was performed in women still having a menstrual cycle.
As early as the discovery of the role of estrogens in the reproductive processes, Russ and Raymund (1956) described that the use of estrogens resulted in an increase of plasma copper level that run parallel to that of ceruloplasmin. Further studies have well confirmed this observation (Prasad et al., 1975b; Sher 1977; Crews et al., 1980; Prema et al., 1980; Chilvers et al., 1985; Berg et al., 1998b). In our study, the mean plasma copper level reached a higher value (1.5 mg/l), i.e. in agreement with the recent study of Benes et al. (2003). A report by Kluft et al. (2002), it has shown that estrogen-containing preparations caused an increase in a specific set of acute-phase proteins elaborated by the liver. Therefore, the increase in plasma copper in OCU is generally explained by the over expression of ceruloplasmin, a copper carrier protein (Limpongsanurak et al., 1981). In contrast, it is interesting to note in our study that women having a plastic T-shaped frame, i.e. wrapped with copper and/or has a copper band presented a plasma copper value that remained within the normal range (0.98 ± 0.32 mg/l). With respect to the correlation between plasma copper and lipid peroxides (Fig. 1), we did not observe in IUD users, plasma levels of lipid peroxides as high as in OCU (Table 3).
As shown in Fig. 2, a cut-off value of 1.2 mg/l in plasma concentration of copper was found to discriminate all the OCU from the others (NCU + IUD). From a biological point of view, it seems to us, however, more relevant to evaluate the copper/zinc ratio since these two trace elements have opposite effects on the oxidative stress. Similarly to iron, copper becomes at high concentration a potent catalyst of free radical production through a Fenton-like reaction (Gaetke and Chow, 2003). In contrast, increased levels of zinc result in the over-expression of antioxidant metallothioneins and in the inhibition of copper-induced free radical species. In our study, the cut-off point for discriminating OCU from all NCU + IUD) was found to be 2.1 for copper/zinc (Fig. 3). From a clinical point of view, it should be highlighted that recent epidemiological studies have described an increased mortality from cardiovascular diseases in subjects with higher serum copper levels (Wu et al., 2004; Leone et al., 2006).
Markers of lipid peroxidation
One of the major findings of the present study was the dramatic and significant increase in lipid peroxides observed in the group of women taking a steroid contraception (Table 3). Oxidative lipid damage was on average 1.77-fold higher in OCU than in NCU. As shown in Fig. 2, a cut-off value of 660 µM for plasma lipid peroxides was found to discriminate all the OCU from the others. As the ELAN women female cohort exhibited a too large diversity in the intake of progestins and steroids (Table 1), we were, however, unable to delineate a different response in intensity of lipid peroxide increase according to the type of OC used (mono, bi and tri-phasic pills). Further investigations should be are necessary to appreciate whether one specific formulation of oral contraceptives could be more responsible for lipid peroxidation than another one. In contrast to lipid peroxides, no modifications were observed at the level of oxidized LDL and Ab-Ox-LDL between all investigated groups.
Several studies in both rats and women have already mentioned an increased level of plasma lipid peroxides due to the use of estrogen (Plaa and Wittchi, 1976; Wynn et al., 1979; Behall et al., 1980; Ciavatti et al., 1989; Subakir et al., 2000). In their animal studies, Ciavatti et al. (1989, 1991) noted that the elevation of lipid peroxides observed in OC-treated rats was able to increase in the plasma the aggregability of platelets exposed both to thrombin and ADP. Such an effect, i.e. potentially involved in the development of venous thromboembolism, may be blocked by antioxidants such as -tocopherol (Wagner et al., 2004), the concentration of which is significantly lower in OCU than in NCU (Table 3).
The change in the copper concentration is certainly the major event leading to the increased level of lipid peroxides. As shown in Fig. 1, a strong and positive correlation was observed between the concentration of plasma copper and lipid peroxides for all women confounded (r = 0.84; P < 0.0001). A similar observation was made concerning the copper/zinc ratio (r = 0.78; P < 0.0001) but with a lower value for the correlation. Relationship between copper (as prooxidant)/zinc (as antioxidant) ratio and circulating lipid peroxides was already reported by Mezzetti et al. (1998) for both men and women. Since the correlation coefficient between the lipid peroxides and the plasma level of copper was 0.84 (P < 0.0001), we used a linear regression to predict the level of lipid peroxides as a function of the level of copper. The expected value of lipid peroxides corresponding to the cut-off value of 1.2 mg/l in copper (see above) was 628 µM. As shown in Fig. 1, the majority of women taking OC were situated outside the area defined by these two points. It should be noted that this value of lipid peroxides was close to those obtained (660 µM) with the predicted model used for discriminating OC from NOC (Fig. 2).
The question is to know if such an increased level of lipid peroxides could have an impact on the health of OCU. Actually, it is well accepted that oxidative damage to lipids and lipoproteins is a process potentially involved in the development of atherosclerosis. In addition to lipid peroxides, we analysed in the ELAN study the concentration of two other markers of lipid peroxidation associated with a higher incidence of cardiovascular diseases: oxidized LDL and their respective antibodies (Holvoet et al., 1998). In contrast to lipid peroxides, no difference was observed between OCU and NCU for both parameters, suggesting that oral contraceptives containing <50 µg of estrogen and second- or third-generation progestins may be reasonably safe from a cardiovascular point of view (Carr and Ory, 1997; Rosenberg et al., 1997). Nevertheless, the increase in lipid peroxides due to OC should be taken into consideration. Further research is necessary to elucidate its real impact as cardiovascular risk factor in OCU.
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Conclusions |
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TopAbstractIntroductionMaterial and MethodsResultsDiscussionConclusionsAuthorship and ContributorshipAcknowledgementsReferences |
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The relationship between estrogens and oxidative stress remains a matter of debate. Estrogens are recognized to be beneficial in the prevention of atherosclerosis although they are capable of inducing oxidative stress, which is involved in the development of the same atherosclerosis. The results of the present study indicate that the intake of estrogens is associated with a significantly altered OSS among women aged 40–48 years. Increase in the concentration of copper, selenium and lipid peroxides and decrease in
-tocopherol and -carotene strongly support this theory. It clearly appears that the plasma copper increase in OCU plays a central role in enhancing lipid peroxidation as evidenced by the strong correlation existing between these two parameters. In our hands, plasma values of copper, lipid peroxides and copper/zinc ratio, respectively, >1.2 mg/l, 660 µM and 2.1, respectively, should be considered in OCU as a potential indication for considering antioxidant supplementation. Checking these parameters in young and older women taking OC should be, therefore, of interest with respect to potential increased risk of developing venous thromboembolism (Ageno et al., 2006) and cardiovascular disorders (Nema et al., 2006). Additional systematic studies, however, are needed to clarify the precise role of oxidative stress mediated by estrogens. |
Authorship and Contributorship |
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TopAbstractIntroductionMaterial and MethodsResultsDiscussionConclusionsAuthorship and ContributorshipAcknowledgementsReferences |
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The ELAN ("Etude Liégeoise sur les ANtioxydants") study was conducted from March through July 2006 as a joint project between the University of Liège, the University Hospital of Liège and the local health services of the Province of Liège (Belgium). Pr JO Defraigne and Dr Sc J Pincemail (CREDEC and Dept of Cardiovascular Surgery, Pr R Limet) were the main coordinators of the ELAN study. They collected all data and wrote the manuscript in the present form with the inestimable help of Pr U Gaspard (Dept of Gynaecology). Pr C Charlier, Pr JP Chapelle and Dr J Haleng (Laboratories of Clinical Biology and Toxicology) allowed the analysis of all biological parameters investigated in the study, except for vitamin C that was performed by Mr JP Cheramy - Bien (CREDEC). Pr D Giet and Dr G Collette (Dept of General Medicine) allowed the recruitment of all general practitioners around the Province of Liège, Belgium. Pr A Albert and Mrs S Vanbelle (Dpt of Medical Informatics and Biostatistics) were involved in the statistical analysis of all data.
All investigators critically revised the manuscript for the intellectual content and gave their final approval of the version to be published.
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Acknowledgements |
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The authors acknowledge the technical assistance of N. Dubois, M. Collard, A. Denooz and E. Brevers. The ELAN study was fully supported by the Department of Health Promotion of the Province of Liège, Belgium.
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References |
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Ageno W, Squizzato A, Garcia D, Imberti D. Epidemiology and risk factors of venous thromboembolism. Semin Thromb Hemost (2006) 32:651–658.[CrossRef][Web of Science][Medline]
Ahotupa M, Rauramo I, Vasankari TJ, Skouby SO, Hakonen T. Estrogen replacement therapy in combination with continuous intrauterine progestin administration reduces the amount of circulating oxidized LDL in postmenopausal women: dependence on the dose of progestin. Ann Med (2004) 36:278–284.[CrossRef][Web of Science][Medline]
Arab L, Schellenberg B, Schlierf G. Nutrition and Health - A survey of young men and women in Heidelberg. Ann Nutr Metal (1982) 26:S1–S244.
Baker H, Handelman GJ, Short S, Machlin LJ, Bhagavan HN, Dratz EA, Frank O. Comparison of plasma alpha and gamma tocopherol levels following chronic oral administration of either all-rac-alpha-tocopheryl acetate or RRR-alpha-tocopheryl acetate in normal adult male subjects. Am J Clin Nutr (1986) 43:382–387.
Bednarek-Tupikowska G, Tworowska U, Jedrychowska I, Radomska B, Tupikowski K, Bidzinska - Speichert B, Milewicz A. Effets of oestradiol and oestroprogestin on erythrocyte antioxidative enzyme system activity in posmenopausal women. Clin Endocrinol (2006) 64:463–468.[Medline]
Behall KM, Moser PB, Kelsay JL, Prather ES. The effect of kind of carbohydrate in the diet and the use of oral contraception on metabolism of young women. Am J Clin Nutr (1980) 33:825–831.
Benes B, Spevackova V, Smid J, Batariova A, Cejchanova M, Zitkova L. Effects of age, BMI, smoking and contraception levels of Cu, Se, Zn in the blood of the population in the Czech Republic. Cent Eur J Public Health (2003) 13:202–207.[CrossRef]
Berg G, Kohlmeier L, Brenner H. Use of oral contraceptives and serum beta - carotene. Eur J Clin Nutr (1997a) 51:181–187.[CrossRef][Web of Science][Medline]
Berg G, Kohlmeier L, Brenner H. Effect of oral contraceptive progestins on serum copper concentration. Eur J Clin Nutr (1998b) 52:711–715.[CrossRef][Web of Science][Medline]
Brown L, Hoong I, Doggrell SA. The heart as a target for oestrogens. Heart Lung Circ (2000) 9:113–125.[CrossRef][Medline]
Bureau I, Laporte F, Favier M, Faure H, Fields M, Favier A, Roussel AM. No antioxidant effect of combined HRT on LDL oxidizability and oxidative stress biomarkers in treated post - menopausal women. J Am Coll Nutr (2002) 21:333–338.
Butterworth PH, Baum H, Porter JW, Ellman GL. A modification of the Ellman procedure for the estimation of protein sulfhydryl groups. Arch Biochem Biophys (1967) 118:716–723.[CrossRef][Web of Science][Medline]
Capel ID, Jenner M, Williams DC, Donaldson D, Nath A. The effect of prolonged oral contraceptive steroid use on erythrocyte glutathione peroxidase activity. J Ster Biochem (1981) 14:729–732.[CrossRef][Web of Science][Medline]
Carr BR, Ory H. Estrogen and progestin components of oral contraceptives: relationship to vascular disease. Contraception (1997) 55:267–272.[CrossRef][Web of Science][Medline]
Chang MC, Hafez ES, Merrilla A, Pincus G. Effect of certain 19-nor steroids on reproductive process in animals. Science (1956) 124:890–891.
Chiang K, Parthasarathy S, Santanam N. Estrogen, neutrophils and oxidation. Life Sci (2004) 75:2425–2428.[CrossRef][Web of Science][Medline]
Ciavatti M, Blache D, Renaud S. Hormonal contraceptive increases plasma lipid peroxides in females rats. Relationship to platelet aggregation and lipid biosynthesis. Arteriosclerosis (1989) 9:84–89.
Ciavatti M, Renaud S. Oxidative status and oral contraception. Its relevance to platelet abnormalities and cardiovascular risk. Free Rad Biol Med (1991) 10:325–338.[CrossRef][Web of Science][Medline]
Chilvers DC, Jones MM, Selby PL, Dawson JB, Hodgkinson A. Effect of oral ethinyl oestradiol and norethisterone on plasma copper and zinc complexes in post - menopausal women. Horm Metab Res (1985) 17:532–535.[Web of Science][Medline]
Clemente C, Caruso MG, Berloco P, Notarnicola M, D'Attoma B, Osella AR, Guerra V, Buonsante A, Giannandrea B, Di Leo A, et al. Antioxidant effect of short - term hormonal treatement in postmenopausal women. Maturitas (1999) 31:137–142.[CrossRef][Web of Science][Medline]
Crews MG, Taper LG, Ritchey SJ. Effects of oral contraceptive agents on copper and zinc balance in young women. Am J Clin Nutr (1980) 33:1940–1945.
Cutler RG. Oxidative stress profiling: part I. Its potential importance in the optimization of human health. Ann NY Acad Sci (2005) 1055:93–135.[CrossRef][Web of Science][Medline]
Dantas AP, Tostes RCA, Fortes ZB, Costa SG, Nigro D, Carvalho MH. In vivo evidence for antioxidant potential of estrogen in microvessels of female spontaneously hypertensive rats. Hypertension (2002) 39:405–411.
Falkeborn M, Lithell H, Persson I, Vessby B, Naessen T. Lipids and antioxidative effects of estradiol and sequential norethisterone acetate treatment in a 3-month randomized controlled trial. Climacteric (2002) 5:240–258.[Web of Science][Medline]
Gaetke LM, Chow CK. Copper toxicity, oxidative stress and antioxidant nutrients. Toxicology (2003) 189:147–163.[CrossRef][Web of Science][Medline]
Galan P, Viteri FE, Bertrais S, Czernichow S, Faure H, Arnaud J, Ruffieux D, Chenal S, Arnault N, Favier A, et al. Serum concentrations of beta-carotene, vitamins C and E, zinc and selenium are influenced by sex, age, diet, smoking status, alcohol consumption and corpulence in a general French adult population. Eur J Clin Nutr (2005) 59:1181–1190.[CrossRef][Web of Science][Medline]
Gey KF. Optimum plasma levels of antioxidant micronutrients—ten years of antioxidant hypothesis on atherosclerosis. Bibli Nutr Diet (1994) 51:84–89.
Gey KF. Vitamins E plus C and interacting conutrients required for optimal health. A critical and constructive review of epidemiology and supplementation data regarding cardiovascular disease and cancer. Biofactors (1998) 7:113–174.[Medline]
Ha EJ, Smith AM. Plasma selenium and plasma and erythrocyte glutathione peroxidase activity increase with estrogen during the menstrual cycle. J Am Coll Nutr (2003) 22:45–51.
Heikkinen AM, Niskanen L, Yla-Herttuala S, Luoma J, Tuppurainen MT, Komulainen M, Saarikosi S. Postmenopausal hormone replacement therapy and antibodies against oxidized LDL. Maturitas (1998) 29:155–161.[CrossRef][Web of Science][Medline]
Hernandez I, Delgado JL, Diaz J, Quesada T, Teruel MJ, Llanos MC, Carbonell LF. 17 - estradiol prevents oxidative stress and decreases blood pressure in ovariectomized rats. Am J Physiol Regul Interg Comp Physiol (2000) 279:R1599–R1605.
Holvoet P, Vanhaecke J, Janssens S, Van de Werf F, Collen D. Oxidized LDL and malondialdehyde-modified LDL in patients with acute coronary syndromes and stable coronary artery disease. Circulation (1998) 98:1487–1494.
Horwitt MK, Harvey CC, Dahm CH. Relationship between levels of blood lipids,vitamins C, A, E, serum copper compounds, and urinary excretions of tryptophan metabolites in women taking oral contraceptive therapy. Am J Clin Nutr (1975) 28:403–412.
Hwang J, Peterson H, Hodis HN, Choi B, Sevanian A. Ascorbic acid enhances 17 -estradiol-mediated inhibition of oxidized low density lipoprotein formation. Atheroscl (2000) 150:275–284.[CrossRef]
Karbownik M, Reiter RJ, Burkhardt S, Gitto E, Tan DX, Lewinski A. Melatonin attenuates estradiol-induced oxidative damage to DNA: relevance for cancer prevention. Exp Biol Med (2001) 226:707–712.
Kluft C, Leuven JA, Helmerhorst FM, Krans HM. Pro-inflammatory effects of estrogens during use of oral contraceptives and hormone replacement therapy. Vascul Pharmacol (2002) 39:149–154.[CrossRef][Web of Science][Medline]
Kose K, Dogan P, Ozesmi C. Contraceptive steroids increase erythrocyte lipid peroxidation in female rats. Contraception (1993) 47:421–425.[CrossRef][Web of Science][Medline]
Leone N, Courbon D, Ducimetiere P, Zureik M. Zinc, copper, and magnesium and risks for all—cause cancer, and cardiovascular mortality. Epidemiol (2006) 17:308–314.[CrossRef][Web of Science][Medline]
Limpongsanurak S, Jenkins N, Fotherby K. Effect of contraceptive steroids on serum levels of sex hormone binding globulin and caerulopasmin. Curr Med Res Opin (1981) 7:185–191.[Web of Science][Medline]
Ling S, Komesaroff P, Sudhir K. Cellular mechanisms underlying the cardiovascular actions of estrogens. Clin Sci (2006) 111:107–118.[CrossRef][Web of Science][Medline]
Markides CS, Roy D, Liehr JG. Concentration dependence of prooxidant and antioxidant properties of catecholestrogens. Arch Biochem Biophys (1998) 360:105–112.[CrossRef][Web of Science][Medline]
Massafra C, Buonocore G, Berni S, Gioia D, Giuliani A, Vezzosi P. Antioxidant erythrocyte enzyme activities during oral contraception. Contraception (1993) 47:591–596.[CrossRef][Web of Science]
McManus J, McEneny J, Young IS, Thompson W. The effect of various oestrogens and progestogens on the susceptibility of low density lipoproteins to oxidation in vivo. Maturitas (1996) 25:125–131.[CrossRef][Web of Science][Medline]
McManus J, McEnemy J, Thompson W, Young IS. The effect of hormone replacement therapy on the oxidation of low density lipoprotein in postmenopausal women. Atherosclerosis (1997) 135:73–81.[CrossRef][Web of Science][Medline]
Mezzetti A, Pierdomenico SD, Costantini F, Romano F, De Cesare D, Cuccurullo F, Imbastara T, Riario-Sforza G, Di Giacomo F, Zuliani G, et al. Copper/zinc ratio and systemic oxidant load: effect of aging and aging - related degenerative diseases. Free Rad Biol Med (1998) 25:676–681.[CrossRef][Web of Science][Medline]
Misra R, Mangi S, Joshi S, Mittal S, Gupta SK, Pandey RM. LycoRed as an alternative to hormone replacement therapy in lowering serum lipids and oxidative stress markers: a randomized controlled clinical trial. J Obstet Gynaecol Res (2006) 32:299–304.[CrossRef][Web of Science][Medline]
Miura T, Muraoka S, Fujimoto Y. Effect of estrogens on the oxidative damage induced by ferrylmyoglobin. J Steroid Biochem Mol Biol (1998) 67:57–62.[CrossRef][Web of Science][Medline]
Mooij P, Thomas C, Doesburt W, Eskes T. Multivitamin supplementation in oral contraceptive users. Contraception (1991) 44:277–288.[CrossRef][Web of Science][Medline]
Mueck AO, Seeger H, Wallwiener D. Fluvastatin combined with 17 - estradiol: effect on the oxidation of human low density lipoprotein. Exp Clin Endocrinol Diabetes (2000) 108:316–317.[CrossRef][Web of Science][Medline]
Nessa A, Latif SA, Siddiqui NI. Risk of cardiovascular diseases with oral contraception. Mymensingh Med J (2006) 15:220–224.[Medline]
Omaye ST, Tumbull JD, Sauerlich HE. Selected methods for the determination of ascorbic acid in animal cells, tissues and fluids. Methods Enzymol (1979) 62:3–11.[Medline]
Palan PR, Rommey SL, Vermund SH, Mikhail MG, Basu J. Effects of smoking and oral contraception on plasma beta-carotene levels in healthy women. Am J Obstet Gynecol (1989) 161:881–885.[Web of Science][Medline]
Palan PR, Magneson AT, Castillo M, Dunne J, Mikhail MS. Effects of menstrual cycle and oral contraceptive use on serum levels of lipid-soluble antioxidants. Am J Obstetrics Gynecology (2006) 194:e35–e38.[CrossRef]
Plaa GL, Wittchi H. Chemical drugs and lipid peroxidation. Ann Rev Pharmacol (1976) 16:125–141.[CrossRef][Web of Science][Medline]
Prasad AS, Lei KY, Oberleas D, Moghissi KS, Stryker JC. Effet of oral contraceptive agents on nutrients: II vitamins. Am J Clin Nutr (1975a) 28:385–391.
Prasad AS, Oberleas D, Moghissi KS, Ley KY, Stryker JC. Effect of oral contraceptive agents on nutrients: I. Minerals. Am J Clin Nutr (1975b) 28:377–384.
Prema K, Ramalakshmi BA, Babu S. Serum copper and zinc in hormonal contraceptive users. Fertil Steril (1980) 33:267–271.[Web of Science][Medline]
Rosenberg L, Palmer JR, Sands MI, Grimes D, Bergman U, Daling J, Mills A. Modern oral contraceptives and cardiovascular diseases. Am J Obstet Gynecol (1997) 177:707–715.[CrossRef][Web of Science][Medline]
Russ EM, Raymund J. Influence of oestrogen on total serum copper and ceruloplasmin. Proc Soc Exp Biol Med (1956) 92:465–466.[Medline]
Saha A, De AU, Sengupta C. Ethinyl estradiol: its interaction on blood-lipid. Indian J Exp Biol (2000) 38:906–911.[Medline]
Seeger H, Wallwiener D, Mueck AO. Additive antioxidative effect of hormone replacement therapy combined with a statin. Clin Exp Obstet Gynecol (2000) 27:179–181.[Medline]
Sher PP. Drug interference with laboratory tests: oral contraceptives. Drug Ther (1977) 2:61–63.[Web of Science]
Sissan MA, Menon VP, Leelamma S. Effects of low-dose oral contraceptive oestrogen and progestin on lipid peroxidation in rats. J Int Med Res (1995) 23:272–278.[Web of Science][Medline]
Souci, Fechmann, Kraut. La composition des aliments, tableaux des valeurs nutritives. (2000) 6th edn. London, England: Medpharm Scientific Publishers.
Sturup S, Hayes RB, Peters U. Development and application of a simple routine method for the determination of selenium in serum by octopole reaction with ICPMS. Anal Bioanal Chem (2005) 381:686–694.[CrossRef][Web of Science][Medline]
Subakir SB, Abdul Madjid O, Sabariah S, Affandi B. Oxidative stress, vitamin E and progestin breakthrough bleeding. Hum Reprod (2000) S3:18–23.
Sugioka K, Shimosegawa Y, Nakano M. Estrogen as natural antioxidant of membrane phospholipid peroxidation. FEBS Letters (1987) 210:37–39.[CrossRef][Web of Science][Medline]
Telci A, Cakatay U, Akhan SE, Bilgin ME, Turfanda A, Sivas A. Posmenopausal hormone replacement hormone therapy use decreases oxidative protein damage. Gynecol Obstet Invest (2002) 54:88–93.[CrossRef][Web of Science][Medline]
Thibodeau PA, Kachadourian R, Lemay R, Bisson M, Day BJ, Paquette B. In vitro pro- and antioxidant properties of estrogens. J Steroid Biochem Mol Biol (2002) 81:227–236.[CrossRef][Web of Science][Medline]
Wakatsuki A, Okatani Y, Ikenoue N, Shinohara K, Watanabe K, Fukaya T. Effect of lower dose of oral conjugated equine estrogen on size and oxidative susceptibility of low-density lipoprotein particles in postmenopausal women. Circulation (2003) 108:808–813.
Wagner KH, Kamal - Eldin A, Elmadfa I. Gamma - tocopherol - an underestimated vitamin? Am Nutr Metab (2004) 48:169–188.[CrossRef]
Wen Y, Doyle MC, Cooke T, Feely J. Effect of menopause on low-density lipoprotein oxidation: is oestrogen an important determinant? Maturitas (2000) 34:233–238.[CrossRef][Web of Science][Medline]
Wu T, Sempos CT, Freudenheim JL, Muti P, Smit E. Serum iron, copper and zinc concentrations and risk of cancer mortality in US adults. Ann Epidemiol (2004) 14:195–201.[CrossRef][Web of Science][Medline]
Wynn V, Adams PW, Godsland I, Melrose J, Niththyananthan R, Oakley NW, Seed M. Comparison of effects of different combined oral-contraceptives on carbohydrate and lipid metabolism. Lancet (1979) 1:1045–1049.[CrossRef][Web of Science][Medline]
Yen CH, Hsieh CC, Chou SY, Lau YT. 17 -estradiol inhibits oxidized low density lipoprotein-induced generation of reactive oxygen species in endothelial cells. Life Sci (2001) 70:403–413.[CrossRef][Web of Science][Medline]
Yeung DL. Relationships between cigarette smoking, oral contraceptives, and plasma vitamins A, E, C, and plasma triglycerides and cholesterol. Am J Clin Nutr (1976) 29:1216–1221.
Zhao B, Tham SY, Lai MH, Lee LK, Moochhala SM. Simultaneous determination of vitamins C, E and beta-carotene in human plasma by high-performance liquid chromatography with photodiode-array detection. J Pharm Pharm Sci (2004) 30:200–204.
Submitted on November 10, 2006; resubmitted on April 4, 2007; accepted on April 17, 2007.
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