TORONTO, Sept. 18 2007 - New scientific research suggests that drinking tea may lower an individual's risk of developing dementia and other neurodegenerative disorders such as Parkinson's and Alzheimer's diseases.
This data and other new research that suggest drinking tea may improve and maintain brain health and function and even help us think more clearly were presented today at the Fourth International Scientific Symposium on Tea & Human Health in Washington, DC. The Symposium is a forum for leading global scientists to gather and share their latest research findings.
"This new data adds to the growing evidence which shows that diet influences the likelihood and risk of an individual experiencing cognitive decline or dementia, including Alzheimer's Disease, with aging," said Canadian tea and health expert Dr. Carol Greenwood.
The body of research presented at the Symposium suggests tea may help maintain and improve brain health both directly and indirectly, said Dr. Greenwood, a Professor of Nutritional Sciences at the University of Toronto, a Senior Scientist at Baycrest in Toronto, and a leading authority on the relationship between diet and cognition.
"The research shows that tea likely directly impacts brain health by maintaining brain cell function and by assisting in the repair of damaged cells," she said. "Drinking tea may further help because it reduces the risk of developing other disorders which increase the risk of cognitive decline and dementia."
One animal study by Dr. Sylvia Mandel, of the Eve Topf Center for Neurodegenerative Diseases in Israel, found that tea consumption helps maintain the health of neurons in the brain and improved their ability to combat stressors, said Dr. Greenwood.
In the study, Dr. Mandel provided an amount of purified tea flavonoids equal to about two to four cups of Green Tea per day to animals with induced Parkinsonism as part of their diet to evaluate how their symptoms improved or progressed. She found that in animals that were fed Green Tea flavonoids, the polyphone appeared to prevent brain cells from dying, and showed improvements in reducing compounds that lead to lesions in the brains of animals with Alzheimer's disease.
"Dr. Mandel's work shows that tea may not only help prevent brain cells from dying, it appears that tea flavonoids may even rescue the neurons once they have been damaged, to help them repair," said Dr. Greenwood.
"Researchers have been actively searching for better ways to support brain cells repair for many years", she said, adding "this finding that tea, a natural product consumed by millions of Canadians every day, can help repair them is especially exciting."
The latest findings on other potential health benefits of tea, including how it may play a role in shifting metabolism to favour weight loss and better manage blood sugar levels, were also unveiled at the Symposium. As well, other new studies which add to the existing body of knowledge about tea's potential ability to reduce risk for several chronic diseases were presented. These included research that shows tea flavonoids may improve cardiovascular health by reducing inflammation and improving blood vessel function.
All of these additional findings also support tea's potential role in preventing cognitive decline and dementia, said Dr. Greenwood. "The research shows that tea may help combat high cholesterol & atherosclerosis, type 2 diabetes and inflammation which are diseases and disorders that increase the risk of dementia."
Furthermore, she added, that tea's potential role in helping to maintain healthy body weight may also help prevent dementia because most of the diseases and disorders associated with risk for cognitive decline and dementia are more prevalent among with those with obesity.
Data which shows how tea impacts brain waves and potentially helps improve the mind's ability to concentrate was also presented at today's Symposium, which was sponsored by the American Cancer Society, American College of Nutrition, American Medical Women's Association, American Society for Nutrition, The Linus Pauling Institute and the Tea Council of the U.S.A.
Results from several ongoing human trials presented at the Symposium by Dr. John Foxe, Professor of Neuroscience, Biology and Psychology at City College of the City University of New York, found that theanine from tea actively alters the attention networks of the brain. Theanine is an amino acid present almost exclusively in the tea plant. After drinking tea, the amino acid theanine, which is present in Green, Black and Oolong varieties, is known to be absorbed by the small intestine and to cross the blood-brain barrier where it affects the brain's neurotransmitters, and increases alpha brain-wave activity. This alpha brain rhythm is known to induce a calmer, yet more alert, state of mind.
Dr. Foxe used electrophysiological measures to monitor brain activity after individuals drank solutions containing either 250 mg theanine or placebo. The subjects were asked to complete a variety of attention-related computerized tasks. "Our results showed that after having theanine, individuals showed significant improvements in tests for attention and that activity in cortical regions responsible for attention functions was enhanced," said Dr. Foxe.
Additional research by Dr. Foxe suggests that the effects of theanine in combination with caffeine are even greater than with either one alone in improving attention. Theanine may work synergistically with caffeine to help induce a more calming, relaxed state, but one that allows the mind to focus and concentrate better at tasks. A cup of tea contains an average of 20-25 mg of theanine.
"What's more, we have seen that just 20 minutes after consuming theanine, the blood concentrations increase and the brain's alpha waves are impacted. It lasts about three to four hours, which we have speculated may be why people tend to drink a cup of tea every three-to-four hours during the day," said Dr. Foxe.
