Story URL: http://news.medill.northwestern.edu/chicago/news.aspx?id=179061
Story Retrieval Date: 12/13/2013 3:36:25 AM CST
Health benefits from regularly drinking green tea may include protection from Alzheimer’s disease and other forms of dementia and cancer.
Debate on health benefits of tea still brewing
Regularly drinking green tea could protect people from Alzheimer’s disease and other forms of dementia as well as cancer, according to a study completed by scientists at Newcastle University, located in northeast England.
Tea has been used for thousands of years as an important part of traditional Eastern medicine for various ailments, in addition to being a beverage, according to Dr. Ed Okello, the lead researcher in the Newcastle study. Today, he said, the three major commercial varieties of tea are black, green, and oolong teas, which all come from the Camellia sinensis plant. Green and oolong teas are especially popular in Asia, while black tea is more popular in the West.
The teas’ health benefits are due to compounds called polyphenols, according to Okello. The polyphenol content in teas varies depending on the kind of tea, where it was grown and the manufacturing process. For example, in black tea, which goes through more processing, polyphenols called catechins are transformed into different forms through oxidation.
Judy Fulop, a doctor of naturopathic medicine at Northwestern Memorial Hospital’s Center for Integrative Medicine and Wellness, explained that green tea leaves and black tea leaves are prepared for consumption through different processes. Green tea leaves are steamed, which leaves the polyphenol content intact. Black tea leaves are dried. The more polyphenols in the tea, the more health benefits there are.
Doctors and herbalists disagree about the potential health benefits of green and black teas. According to Okello, studies indicate there may be benefits including prevention of cancer, heart disease, diabetes, obesity and neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease.
Dr. Michael Seidman, medical director for Henry Ford Health System’s Center for Integrative Medicine and head of integrative medicine at the Henry Ford West Bloomfield Hospital, said the antioxidants in black and green teas have anti-inflammatory properties. “Inflammation is a precursor for many things,” he said - including heart disease, cancer and neurodegenerative problems.
Seidman said regular consumption of black and green teas may lower cholesterol, and drinking green tea reduces the risk of cancer.
But Seanna Tully, clinical services manager of the Apothecary at Whole Health Chicago, said the benefits of teas made from Camellia sinensis are still being researched. For example, there is not enough evidence to say definitively that green tea prevents cancer.
Marc Gentzler, spokesman for the Chicago-based Alzheimer’s Association, said there is little scientific information indicating that tea drinking helps prevent Alzheimer’s. He said the best prevention method is to stay healthy and active.
But green tea does have other benefits, Tully said. It can play a role in preventing tumor formation, and it has metabolic effects as well.
Seidman said that while some studies showed weight loss in moderately obese patients who drank black and green teas, there is conflicting evidence about their effect due to the presence of caffeine and stimulants in the teas.
People in Asia, where they consume more green tea than do Westerners, have a lower incidence rate of of certain diseases. For example, Seidman said Japanese adults who drink at least six cups of green tea a day have a 33 percent lower risk of developing Type II diabetes compared with those who drink one cup or less.
Dr. Chun-Su Yuan, director of the University of Chicago Medical Center’s Tang Center for Herbal Medicine Research, said the antioxidants in green tea protect the cardiovascular system and strengthen the immune system, while promoting overall health.
Doctors recommend drinking black and green teas regularly to maximize the health benefits. Yuan said people should drink tea multiple times a day the way they drink coffee; Seidman recommends three to seven cups a day, in addition to a balanced diet.
Decaffeinated tea should still have the same benefits as caffeinated tea, Yuan said.
Seidman and Yuan disagree over whether the temperature of tea is important. Seidman said as long as it has been steeped in hot water at some point to extract the polyphenols, the health benefits will still be present whether one drinks it hot or cold.
But Yuan said the polyphenol levels in tea could be reduced if the tea is allowed to sit after steeping, exposed to air and subject to oxidation. If someone does not want to drink scalding hot tea, he suggests adding an ice cube to cool the tea and drinking it quickly before oxidation can occur.
Other herbal teas are also good for health and wellness. “Drinking tea in a relaxed environment affects not only the body but also the mind and spirit,” Fulop said. Tea can have a placebo effect, calming the nervous system and the body.
Lavender and chamomile teas are good for relaxing, and chamomile, mint, and ginger teas help digestion. Mint and ginger teas help regulate the immune system.
Ginger tea is excellent for cramps, as well as cold and flu symptoms. Fulop recommends drinking it while taking a hot bath, and wrapping up in a blanket to sweat out an illness.
Ginger tea helps with heartburn and nausea related to motion sickness or chemotherapy. Seidman said cancer patients often drink it and suck on ginger lozenges to fight the side effects of chemotherapy.
Fulop said that herbal stores can make combination teas with multiple herbs to help one or more health problems. For example, recovering drug addicts sometimes drink a chamomile and oat straw tea, which calms the nervous system. Adding lemon balm adds flavor in addition to helping calm the nervous system.
Yuan agreed that mixing different herbs together combines their effects and flavors.
Doctors and herbalists agree that tea should not be the only remedy someone uses for an illness. Seidman, as an integrative medicine practitioner, believes it is important to take advantage of both conventional and alternative medicine.
Fulop agreed that tea should never be a substitute for any medication. Patients should work with a practitioner to determine what herbs may work for their illnesses, and communicate with doctors if their symptoms change and they need to adjust their medications.
The U.S. Food and Drug Administration considers teas safe. Herbalists agree that they have few side effects, but still recommend caution. Fulop said some herbs are toxic to the liver. “People need to be aware of what they’re doing if they’re going to make their own teas (with herbs they collect themselves),” she said.
Fulop cautions individuals with hypertension against consuming licorice tea, which can cause potassium loss and sodium and water retention. Additionally, the loss of potassium can affect the heart.
Some herbs react with prescription drugs. For example, many herbs react with anticoagulant medications. Seidman advises people on blood thinners to consult a doctor. He also said there is a relationship between caffeine and high blood pressure and heart rate.
“Most of these aren’t terribly clinically relevant, but they’re things you have to be careful of,” he said.
According to the National Cancer Institute, excessive amounts of caffeine could have side effects including heart palpitations, insomnia, restlessness, nervousness, tremors, headache, nausea and diarrhea.
People with a ragweed allergy may want to avoid chamomile, said Fulop. Peppermint tea, which soothes stomach and menstrual cramps, can relax the sphincter going into the stomach, causing acid reflux.
However, teas generally have fewer side effects than herbal capsules because teas are diluted forms of the herbs.
“Many people had tea as the basis of their culture,” Fulop said. “Just like we have Starbucks today, they would get together over a cup of tea. If we could spend time around a campfire with a good cup of tea, we could solve a lot of problems.”