Promising Tea Research Addresses Three Conditions

WASHINGTON, D.C.

World Tea NewsThe breadth of last week’s scientific research on the health benefits of tea is breathtaking.
 
During the past five years 5,649 laboratory, clinical and meta-studies of tea worldwide conclusively demonstrate its wide-ranging benefits.  The study of tea itself is now seen as the tea-health field with branches investigating benefits to mental acuity, heart health, bone and muscles, cancer prevention and tumor reduction and even weight loss.
 
Drinking tea daily is a simple pleasure but “when you translate all of this data, a little increase in bone strength, a decrease in blood pressure, across a whole population, little changes make a big difference,” said Dr. Jeffrey Blumberg who chaired the 5th International Scientific Symposium on Tea and Human Health. 
 
"There is now an overwhelming body of research from around the world indicating that drinking tea can enhance human health,” Dr. Blumberg said. "The many bioactive compounds in tea appear to impact virtually every cell in the body to help improve health outcomes, which is why the consensus emerging from this symposium is that drinking at least a cup of green, black, white or oolong tea a day can contribute significantly to the promotion of public health."
 
“Bottom line” Blumberg told The Atlantic, unlike the many popular beverages that do harm, tea is healthful and it “contains zero calories." 
 
Blumberg is professor at the Friedman School of Nutrition Science at Tufts University. He briefed reporters Sept. 19 at the D.C. headquarters of the U.S. Department of Agriculture on the latest findings related to health.
 
  • Only one cup of black tea per day may improve blood vessel function, lower blood pressure and reduce the incidence of stroke, heart attack and other cardiovascular diseases by 10%.
  • Just one cup of tea may boost one’s ability to solve difficult language and mathematical problems.
  • Drinking two cups of black tea may help raise one’s alertness and attention span.
  • Tea has anti-cancer properties: Men who drank more than 1.5 cups of green tea per day had a 70% lower color cancer risk.
  • Two cups of black tea per day have been shown to enhance work performance, reduce tiredness and improve clarity and energy. 
  • Black tea may also help to improve cognitive functional in particular, attention.
  • Drinking several cups of green tea may help burn 100 calories a day.
  • Drinking tea along with a weight-bearing exercise like Tai Chai are an effective way to improve muscle strength, reduce inflammation and improve low bone mass, which may help to reduce the risk for osteoporosis and fractures, especially among the elderly.
 
Tea is not viewed as a typical green, leafy vegetable promoted by the USDA, but Blumberg pointed out that the flavonoids extracted from tea leaves are similar to the beneficial phytochemicals found in fruits and vegetables. If we can't get Americans to eat the recommended daily amounts of fruits and vegetables, he suggests, why not let tea count as one or two servings?
 
The benefits may go beyond those gained from adding more plant food to your diet. The research presented at the symposium covered the gamut of health benefits attributed to tea — from reduced risks of gastrointestinal cancers to improved mental acuity in older adults. And new studies suggest that tea could play an important role in three major public health issues:
 
Tea and Body Weight 
 
Obesity is the largest public health concern in the United States and there are few strategies that provide long-term success. New research on tea catechins suggests that they may provide a benefit in maintaining body weight or promoting weight loss. In a comprehensive review of the published data on this topic, researchers from Maastricht University, Maastricht, The Netherlands, found that 24-hour energy expenditure and fat oxidation increased when subjects consumed green tea and caffeine. The results of a meta-analysis suggest that the increase in caloric expenditure is equal to about 100 calories over a 24-hour period, or 0.13 calories per mg catechins. In addition, green tea and caffeine also appear to boost fat oxidation over 24 hours by an average of 16% or 0.02 grams per mg catechins. In a related review, researchers concluded that subjects consuming green tea and caffeine lost an average of 2.9 pounds within 12 weeks, while adhering to their regular diet.
 
Beverages now account for 20% of total calories in the typical American diet. "As tea is calorie-free, it's an ideal choice to help consumers meet fluid requirements without adding calories to their diet, and the modest increase in energy expenditure and fat oxidation can also add to the role of tea as part of a healthy, calorie-controlled diet that promotes weight loss or maintenance," explains researcher Rick Hursel, PhD, of Maastricht University, The Netherlands.
 
Tea and Bone and Muscle Strength 
 
Osteoporosis is a major public health concern for many older women and men as the disease is responsible for two million fractures a year and 300,000 hip fractures in 2005. The disease leads to loss of mobility, independence and reduces quality of life for many older Americans.
Researchers at Texas Tech University Health Sciences Center conducted studies with 150 postmenopausal women with low bone mass to see if the addition of green tea flavanols, Tai Chi exercise or both green tea plus Tai Chi could help improve markers for bone health and muscle strength in study participants. At the end of the six-month clinical trial they found that 500 mg green tea extract (equivalent to 4-6 cups of green tea daily), alone or in combination with Tai Chi, improved markers for bone formation, reduced markers of inflammation and increased muscle strength in study participants.
 
"The results of our study are consistent with earlier work suggesting that green tea flavanols exert bone health benefits by reducing inflammation and providing antioxidant protection. Our work suggests that green tea and weight bearing exercise like Tai Chi may be an effective way to help improve muscular strength, reduce inflammation and improve bone biomarkers, which may help reduce the risk for osteoporosis and fractures among older Americans," said Chwan-Li (Leslie) Shen, PhD, the lead researcher at Texas Tech University Health Sciences Center in Lubbock, TX. 
 
Tea May Improve Mental Sharpness
 
Consuming black tea improved attention and self-reported alertness in a human study conducted by Unilever R&D, Vlaardingen, The Netherlands. In this placebo-controlled study, designed to measure attention, task performance and alertness, subjects drinking tea were more accurate on an attention task and also felt more alert than subjects drinking a placebo. This work supports earlier studies on the mental benefits of tea. In addition, two other studies provide a broader perspective on tea's effects on psychological well-being, showing benefits for tiredness and self-reported work performance, as well as mood and creative problem solving. These studies provide support for tea's benefits for mental sharpness, as measured by attention, mood and performance. 
 
According to symposium presenter Suzanne Einother, PhD, Unilever R&D, Vlaardingen, The Netherlands, "In our study with adult subjects, we found drinking tea improved attention and allowed individuals to be more focused on the task at hand. These effects were found for two to three cups of tea consumed within a time period of up to 90 minutes."
 

COMMENT