The purpose of this study is to evaluate the beneficial effects of a long term (12 weeks) green tea drinking on plasma, erythrocytes and saliva oxidative stress biomarkers and antioxidant capacity, as well as on cardiometabolic risk factors: anthropometric, inflammation and metabolic parameters in a healthy aging men and women.
A prospective, crossover trial in which every individual served its own control. All subjects undergo a four weeks washout period, during which they briefed to avoid tea drinking and antioxidant supplements until the end of the study. At the end of the washout period, blood and saliva samples is collected after 12 hours of night fast. Subsequently, all subjects receive the maltodextrin containing placebo "tea bags". The subjects instructed to brew the placebo sachets for five minute in 240 mL boiling water without stirring and to drink 4 cups per day for 12 weeks period (placebo period). After the placebo period, fasting samples collected once more and the subjects receive the green tea bags. Preparation and drinking instructions are the same as the placebo drink. At the end of the 12 weeks, green tea drinking, fasting blood and saliva samples drawn for the third time. During the study, every 4 weeks the subjects get additional placebo or green tea bags. Assessment of nutritional consumption of macronutrients and antioxidants using a food diary, physical activity lifestyle as well as weight, body fat and circumference measurements is made at the beginning, middle and end of the study.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
43
Four green tea bags per day for 12 weeks
4 daily placebo tea bags for 12 weeks
Rambam MC
Haifa, Israel
Plasma protein carbonyls
Protein carbonyls, nmol/mg
Time frame: 24 weeks
Plasma thiobarbituric acid reactive substance
Thiobarbituric acid reactive substance , nmol/mL
Time frame: 24 weeks
Plasma lipid peroxides
Lipid peroxides, nmol/mL
Time frame: 24 weeks
Erythrocytes catalase
Catalase activity, milliunits/mg
Time frame: 24 weeks
Erythrocytes resistance to oxidative hemolysis
hemolysis test, percentage
Time frame: 24 weeks
Saliva enzymatic antioxidants
Oral peroxidase activity, milliunits/mg
Time frame: 24 weeks
Saliva antioxidant capacity
Total antioxidant capacity, millimolar/mg
Time frame: 24 weeks
Total body weight
Body weight, kg
Time frame: 24 weeks
Total body fat percentage
Body fat, %
Time frame: 24 weeks
Body circumference
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Waist and hip circumference, cm
Time frame: 24 weeks
Serum inflammatory status
Serum C-reactive protein mg/dL
Time frame: 24 weeks
Saliva inflammatory status Saliva matrix metalloproteinase 8 (MMP8)
Saliva matrix metalloproteinase 8, µg/L
Time frame: 24 weeks
Saliva inflammatory status - saliva interleukin 8 (IL8)
Saliva interleukin 8, ng/L
Time frame: 24 weeks