|Ph.D Student||Narotzki Baruch|
|Subject||Green Tea and Physical Activity - Effects on|
Cardiometabolic Risk Factors and Oxidative Status
in the Elderly
|Department||Department of Medicine||Supervisors||ASSOCIATE PROF. Abraham Reznick|
|PROF. Dror Aizenbud|
|CLINICAL PROFESSOR Yishai Levy|
|Full Thesis text|
Sedentary lifestyle augments age related diseases, while physical activity (PA) reduces those diseases, but increases reactive oxygen species (ROS) formation. Green tea (GT) is rich in polyphenols and has potential cardiovascular benefits. However, its interaction with PA and specifically in elderly people has not been yet determined. We have hypothesized that antioxidants supplementation to elderly people may attenuate exercise-related oxidative damage and that GT modification of cardiometabolic risk may be dependent on prior PA.
We report on the exercise enhancing effects of 12-weeks GT drinking (3 cups/d) and vitamin E (400 IU) on weight and waist circumference and on glucose metabolism, in 22 elderly men and women. Plasma biomarkers of oxidative damage (protein carbonyls) dropped and erythrocyte catalase activity (H2O2 scavenger) increased.
In the next project we have conducted, four GT cups/d were given for 12-weeks to 43 elderly subjects. Physical Activity Scale for the Elderly (PASE) questionnaire assessed PA level. GT had PA-dependent effects. In subjects with active lifestyle, HDL increased and LDL/HDL-cholesterol ratio decreased more than in the less active subjects. An opposite trend was observed regarding body weight and fasting glucose. Oxidative status parameters were not related to PA level. Erythrocytes' ability to resist oxidation-induced hemolysis and saliva total antioxidant capacity were enhanced. GT did not affect inflammatory status as monitored by serum CRP and salivary IL-1β and MMP-8.
Since aging and obesity are both linked to elevated oxidative stress, we have analyzed the influence of excessive body fat on oxidative status. Excessive vs. normal body fat (6% higher), resulted in an increase in cardiometabolic risk. In this group, oral peroxidases (OPO) enzymes activities were compromised.
Oral peroxidases enzymes can be activated by exercise as seen in our clinical trial. An exercise-induced elevation of nitric oxide and salivary nitrites was suggested as a cause of OPO activity increase. Our In Vitro experiments confirmed nitric oxide activation of OPO enzymes, which were also modified by GT.
The effect of GT on HDL elevation may be due to an exercise-dependent pathway with activation of the peroxisome proliferator-activated receptor-γ coactivator-1α. GT effects on body weight and glucose metabolism are suggested to act in pathways similar to exercise, such as increase in adipocyte glucosetransporter-4 (GLUT-4) and sympathetic nervous system activation. Collectively, our work uncovers GT, vitamin E, PA and body fat effects on the anthropometric, metabolic, inflammatory and anti-oxidative status in healthy elderly men and women.