| Author: | Lo, Wai-mei Rita |
| Title: | To study and compare the effects of two kinds of green tea (Loongjin and Screwed-shaped green tea) for health promotion, with particular focus on biomarkers of oxidant/antioxidant balance in a controlled human intervention trial |
| Degree: | M.Sc. |
| Year: | 2009 |
| Subject: | Hong Kong Polytechnic University -- Dissertations. Green tea -- Therapeutic use. Cardiovascular system -- Diseases -- Alternative treatment. |
| Department: | Department of Health Technology and Informatics |
| Pages: | xii, 138 leaves : ill. (some col.) ; 30 cm. |
| Language: | English |
| Abstract: | Vitamin C and vitamin E had been investigated to great extend for their antioxidant effects on delay of onset of oxidative stress related diseases. In recent researches, more investigation has been directed to some other antioxidant rich diet. Tea is one of the candidates suitable for the study for its increasingly recognized antioxidant property and its convenience as daily supplementation. The aim of this study was to test if the effect of green tea polyphenols supplementation can improve the total antioxidant capacity, plasma antioxidants concentration, red cell antioxidant enzymes activity and decrease lipid peroxidation in human. The antioxidant properties of green tea may also help to upgrade the body's defense against oxidative stress by increasing the total antioxidant capacity, upregulating the antioxidant enzymes and decreasing the progress of oxidation in various molecular levels. The hypothesis is that flavonoid in green tea can act as antioxidant, replace and spare the vitamin E to prevent the preoxidation of low density lipoprotein (LDL). As Vitamin C and polyphenols may "spare" vitamin E, green tea may in turn spare the vitamin C as the latter is less consumed in the antioxidant defense mechanism. In this single-blinded cross over study, 18 apparently healthy subjects (nine men and nine women) consumed 1.5 g green tea twice per day for 4 weeks in each intervention. Two kinds of mostly consumed Chinese green tea, the Loongjin green tea and the Screw shaped green tea were evaluated for the beneficial effects on antioxidant balance. Each subject acted as own placebo control and took the two kinds of green tea in turn. The whole study consisted of 3 intervention periods and separated by 6-week washout period between interventions. Total antioxidant capacity, plasma ascorbic acid and lipid standardized vitamin E concentration, red cell antioxidant enzymes of superoxide dismutase (SOD), glutathione peroxidase (GPx), lipid peroxidation products of malondialdehyde (MDA) and uric acid (UA) oxidation products of allantoin were measured to reveal the effects of green tea supplementation. In this study, there was no clear cut evidence of effects of the two kinds of green tea on various studied biomarkers as compared with placebo. However, the results may suggest a slight beneficial effect of the Screw shaped green tea in the oxidative status. Further study on these two kinds of green tea for their long term effect may needed to explore the dose, their role and effects on the whole body oxidative balance. |
| Rights: | All rights reserved |
| Access: | restricted access |
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| File | Description | Size | Format | |
|---|---|---|---|---|
| b23056113.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 8.3 MB | Adobe PDF | View/Open |
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