Dokument: Oxidants and Antioxidants in Human Health. Nutritional Intervention Study Based on the Campaign "5 a Day"
| Titel: | Oxidants and Antioxidants in Human Health. Nutritional Intervention Study Based on the Campaign "5 a Day" | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=3416 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20060606-001416-3 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | Carrillo Pelaez, Juan-Carlos [Autor] | |||||||
| Dateien: |
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| Beitragende: | Prof. Dr. Stahl, Wilhelm [Gutachter] Prof. Dr. Wunderlich, Frank [Gutachter] | |||||||
| Stichwörter: | Carotinoide, antioxidantien, biomarker, 5 am Tag, obst, gemüse, intervention, liposomenCarotenoids, antioxidants, biomarker, 5 a day, fruits, vegetables, intervention, liposomes | |||||||
| Dewey Dezimal-Klassifikation: | 600 Technik, Medizin, angewandte Wissenschaften » 610 Medizin und Gesundheit | |||||||
| Beschreibungen: | Epidemiological studies have shown a clear correlation between the increased consumption of antioxidant-rich foods and a decreased risk for several diseases related to oxidative stress. Consequently, a daily intake of at least 400 g of fruit and vegetables has been recommended by the WHO and the world wide campaign "5 a Day" aims at achieving this recommendation. In the frame of the present thesis an intervention study on a working population within the world wide campaign of "5 a Day" was carried out to test whether a counseled diet of five portions of fruits and vegetables a day for a period of 3 months, leads to an increase in antioxidant/micronutrient levels in blood and consequently to a decrease in biomarkers for oxidative stress and cardiovascular diseases. Blood levels of antioxidants/micronutrients as well as biomarkers for oxidative stress and cardiovascular diseases were analyzed by means of HPLC and ELISA. Another aspect of the study was to evaluate volunteers' compliance and collect information about the consumption of specific food items. Increases in micronutrient levels (especially carotenoids) were compared and correlated to intake frequencies of selected food. The present work shows dietary counseling is efective in motivating individuals from a working population to increase their daily fruit and vegetable intake. The intervention not only increased fruit and vegetable intake of individuals with an almost optimal consumption of these foods, but also kept participants motivated and interested. Concomitantly to the increase in fruit and vegetable intake, levels of circulating antioxidants and micronutrients were significantly increased over base line. Although levels of antioxidants and micronutrient increased, biomarkers of oxidative damage were not afected by the intervention. It is concluded that a further increase of dietary antioxidants in a healthy and already well-nourished population has no lowering effect on the selected biomarkers of diseases related to oxidative stress. No apparent improvement of health conditions and/or benefit from an increased defense systems against oxidative damage were observed. The lack of an effect on biomarkers of oxidative stress may be due to the short duration of the intervention (3 months). Also the suitability of the biomarkers as selective indicators for oxidative stress conditions or cardiovascular diseases may be questionable. Additionally, those carotenoids, which increased in blood levels, were further tested for their antioxidant properties alone and in combinations to determine possible synergistic effects in liposomes. Carotenoid mixtures and single compounds were also evaluated for antioxidant potency and synergism in a single compartment model using homogeneous solutions. In vitro systems provide a suitable tool to understand the antioxidant properties of dietary constituents. It has been shown that a bilayer membrane system such as unilamellar liposomes, can be used to mimic the structure of a cell membrane to test antioxidants for additive and/or synergistic effects. In the present work mixtures of carotenoids in unilamellar liposmes had an additive antioxidant effect in oxidative stress conditions. Furthermore the model of unilamellar liposomes is superior to that of multilamellar systems when investigating antioxidant effects in vitro. Combining results from in vivo modeling of prooxidant/antioxidant reactions with intervention studies is essential to understand mechanisms of oxidative damage and and develop strategies of defense including the use of dietary components.Epidemiological studies have shown a clear correlation between the increased consumption of antioxidant-rich foods and a decreased risk for several diseases related to oxidative stress. Consequently, a daily intake of at least 400 g of fruit and vegetables has been recommended by the WHO and the world wide campaign "5 a Day" aims at achieving this recommendation. In the frame of the present thesis an intervention study on a working population within the world wide campaign of "5 a Day" was carried out to test whether a counseled diet of five portions of fruits and vegetables a day for a period of 3 months, leads to an increase in antioxidant/micronutrient levels in blood and consequently to a decrease in biomarkers for oxidative stress and cardiovascular diseases. Blood levels of antioxidants/micronutrients as well as biomarkers for oxidative stress and cardiovascular diseases were analyzed by means of HPLC and ELISA. Another aspect of the study was to evaluate volunteers' compliance and collect information about the consumption of specific food items. Increases in micronutrient levels (especially carotenoids) were compared and correlated to intake frequencies of selected food. The present work shows dietary counseling is efective in motivating individuals from a working population to increase their daily fruit and vegetable intake. The intervention not only increased fruit and vegetable intake of individuals with an almost optimal consumption of these foods, but also kept participants motivated and interested. Concomitantly to the increase in fruit and vegetable intake, levels of circulating antioxidants and micronutrients were significantly increased over base line. Although levels of antioxidants and micronutrient increased, biomarkers of oxidative damage were not afected by the intervention. It is concluded that a further increase of dietary antioxidants in a healthy and already well-nourished population has no lowering effect on the selected biomarkers of diseases related to oxidative stress. No apparent improvement of health conditions and/or benefit from an increased defense systems against oxidative damage were observed. The lack of an effect on biomarkers of oxidative stress may be due to the short duration of the intervention (3 months). Also the suitability of the biomarkers as selective indicators for oxidative stress conditions or cardiovascular diseases may be questionable. Additionally, those carotenoids, which increased in blood levels, were further tested for their antioxidant properties alone and in combinations to determine possible synergistic effects in liposomes. Carotenoid mixtures and single compounds were also evaluated for antioxidant potency and synergism in a single compartment model using homogeneous solutions. In vitro systems provide a suitable tool to understand the antioxidant properties of dietary constituents. It has been shown that a bilayer membrane system such as unilamellar liposomes, can be used to mimic the structure of a cell membrane to test antioxidants for additive and/or synergistic effects. In the present work mixtures of carotenoids in unilamellar liposmes had an additive antioxidant effect in oxidative stress conditions. Furthermore the model of unilamellar liposomes is superior to that of multilamellar systems when investigating antioxidant effects in vitro. Combining results from in vivo modeling of prooxidant/antioxidant reactions with intervention studies is essential to understand mechanisms of oxidative damage and and develop strategies of defense including the use of dietary components. | |||||||
| Lizenz: |  Urheberrechtsschutz | |||||||
| Fachbereich / Einrichtung: | Medizinische Fakultät | |||||||
| Dokument erstellt am: | 06.06.2006 | |||||||
| Dateien geändert am: | 12.02.2007 | |||||||
| Promotionsantrag am: | 10.05.2006 | |||||||
| Datum der Promotion: | 10.05.2006 |
