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Drinking Tea After Smoking May Reduce Oxidative Stress

Drinking Tea After Smoking May Reduce Oxidative Stress

WASHINGTON—Forget those smoke-filled cocktail lounges, tobacco addicts, and head for a local tea room. “Drinking tea after smoking reduces levels of oxidative stress,” reported James E. Klaunig, PhD, professor of pharmacology and toxicology, Indiana University School of Medicine. Oxidative stress has been linked to cancer and other diseases .

What Causes Oxidative Stress?

Oxidative stress may be due to either decreased levels of antioxidants or increased levels of reactive oxygen species in the body. It is linked to cancer, cardiovascular disease, aging, and neurodegenerative diseases such as Parkinson’s and Alzheimer’s disease, Dr. James Klaunig said at the tea symposium.

There are two sources of the reactive oxygen species that result in oxidative stress, he said. Some arise within the body in mitochondria, in inflammatory cells, and from cytochrome p450. Exogenous sources include ozone, radiation, xenobiotics, and hyperoxemia.

Tobacco smoke is a known source of reactive oxygen species that can overwhelm the normal antioxidant defenses of the individual, resulting in oxidative stress. Increasing antioxidant levels could prevent this scenario. Dr. Klaunig reported higher levels of oxidative stress in the urine and blood of smokers vs nonsmokers.

Dr. Klaunig spoke at the Second International Scientific Symposium on Tea and Human Health, cosponsored by the American Health Foundation, the American Cancer Society, the Nutrition Committee of the American Heart Association, and the Tea Council of the USA.

Along with his colleagues J. Chen and C. Han from the Chinese Academy of Preventive Medicine, Beijing, Dr. Klaunig set out to study, in smokers, the effects of tea drinking on oxidative damage, production of reactive oxygen species, and modulation of antioxidants.

In the China arm of the study, army recruits drank three cups of green or black tea a day and were allotted six cigarettes a day to smoke after meals. After one week, the smokers showed a “dramatic” decrease in reactive oxygen species and oxidative stress, Dr. Klaunig said. Green tea had a greater effect than black tea.

Back home in Indiana, Dr. Klaunig recruited volunteers aged 25 to 45. They were either nonsmokers or pack-a-day smokers. The volunteers quaffed a total of 30 ounces of green tea daily, drinking the tea four times a day with meals and snacks. Neither diet nor physical activity was controlled.

Baseline tests of levels of 8-hydroxy-2´-deoxyguanosine and lipid peroxidation (measures of oxidative stress) showed that smokers had higher levels of oxidative stress prior to the trial’s start. While both smokers and nonsmokers showed a reduction in oxidative stress parameters during the study, the smokers exhibited a much greater response to drinking tea.

Using the Syrian Hamster Embryo (SHE) Cell Transformation Assay, Dr. Klaunig found that components from black and green tea “prevented or reduced carcinogen-induced cell transformation in a dose-dependent manner.”

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