Drink iced teas for good health, but they must be true teas
Marukyu Koyamaen's tea room, courtesy of Yumi Nakatsugawa
National Iced Tea month (in the United States) may be ending soon, but for many the summer has just begun. And iced tea can be that perfect summer drink, because even iced, true teas – not fruit or herbal teas – offer numerous health benefits.
Earlier this year at the Sixth International Scientific Symposium on Tea and Human Health, leading nutrition scientists from around the world convened to present the latest evidence supporting the role of tea in promoting optimal health. With new findings from the international scientific community continuing to evidence tea’s healthy properties.
“There is a growing body of research from around the world demonstrating that drinking tea can enhance human health in many ways,” said symposium chair, Jeffrey Blumberg, PhD, an active Professor Emeritus in the Friedman School of Nutrition Science and Policy at Tufts University in Massachusetts. “True teas, which include black, green, white, oolong, and dark, can contribute significantly to the promotion of public health. Evidence presented at this symposium reveals results – ranging from suggestive to compelling – about the benefits of tea on cancer, cardiometabolic disease, cognitive performance, and immune function.”
So, for example, while no one is suggesting forgoing the use of sunscreen, green tea polyphenols have been linked to increased skin protection from UV (ultraviolet) rays and improved elasticity (microcirculation). In a 12-week trial, where women were randomised to drinking extracted green tea polyphenols, they saw improvements in skin elasticity, roughness and scaling thought to be a result of increased blood flow and oxygen delivery to the skin (per Heinrich U, Moore CE, De Spirt S, Tronnier H, Stahl W, J Nutr 2011; 141:1202-8).
Green tea/catechins have been shown to help immune systems fight illnesses and improve auto-immune disorders (per Rawangkan et al. Molecules, 2021). “Tea may help support your immune system and increase your body’s resistance to illnesses,” said Dayong Wu, MD, PhD, Nutritional Immunology Laboratory in the USDA Jean Mayer Human Nutrition Research Center on Aging at Tufts University. “In the event you do become sick, tea can help your body respond to illness in a more efficient way by ridding itself of the infection and may also alleviate its severity when they happen.”
In his presentation at the symposium, Wu explained that green tea/catechins have been shown to help the host fight against a variety of pathogens by decreasing the pathogen’s ability to infect the host and helping the host’s immune system spring into action. Additional research has revealed that green tea/catechins improve autoimmune disorders by promoting self-tolerance, suppressing autoantigen-induced inflammatory attacks, and enhancing tissue repair.
Furthermore, when it comes to cognitive function, tea may offer significant benefits. “There is strong evidence that tea and its constituents seem to be beneficial under conditions of stress. The most profound cognitive domain that tea seems to act upon is attention and alertness,” noted Louise Dye, PhD, Professor of Nutrition and Behaviour at the University of Leeds in the United Kingdom. “With these effects on attention, tea is an optimal beverage of choice during a time of elevated stress and burnout worldwide.”
In her review of published research on this subject, Dye revealed that evidence from randomised controlled trials supports the conclusion that tea consumption can produce short term acute beneficial effects on attention (measured by objective tests such as the attention switching test and on subjective reports of alertness). She noted that studies consistently show beneficial effects of a high dose of L-theanine, together with a lower dose of caffeine, on attention task performance. These findings indicate that the unique combination of caffeine and L-theanine that is found in tea can improve attention.
So, while out and about enjoying all the fun activities summer has to offer, keep hydrated and perhaps try an iced tea, but remember, to achieve the touted health benefits, it must be a true tea!
- Vanessa L Facenda, editor, Tea & Coffee Trade Journal.
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