With the onset of cold weather comes the dreaded cold and flu season. Aside from the flu vaccine, people often wonder what they can do from getting sick this year. Besides having a full night’s rest, clean hands, and a proper diet, drinking tea can help fight back the flu.
Tea leaves produce organic compounds that help defend the plant against infection. These same compounds are preserved in both green and black tea, and have been shown to inhibit the spread and growth of the flu virus. Numerous studies have found that both tea and tea extracts significantly reduces the incidence of flu in the young, elderly, and healthcare workers who are at higher risk of infection.
In addition to vitamins and caffeine, certain beneficial compounds are present in green tea—catechins. Catechins have been shown to have antioxidative, antitumor, and antiviral properties. These compounds are concentrated as tea leaves are dried, and account for about 10% of the dry weight of green tea. Catechins interfere with the flu virus before it infects cells, and throughout the infection cycle, essentially throwing a monkey wrench in the machinery of the flu virus.
While catechins are more concentrated in green teas, they are present in oolong and black teas as well. In addition, catechins are oxidized during the fermentation of oolong and black teas, turning the catechins into theaflavins. Theaflavins impart a black color in black and oolong teas, and posses antimicrobial properties as well.
In essence, green teas as well as fermented teas such as oolong and black teas possess an array of healthy compounds that fight the flu before and after infection. The more tea that is consumed throughout the day, the more these beneficial compounds come in contact with any flu virions attempting to enter the body. One study among elderly home residents involved gargling a tea extract three times daily. The idea being that the throat is a major site of infection. By gargling the tea, the contact time with the throat was increased. The result was that only 1.3% of those who gargled tea contracted the flu, compared to a nearly tenfold increase in the incidence of flu among those who didn’t gargle.
Aside from the benefits of the catechins, theflavins, vitamins, and caffeine present in tea, there is the important benefit of rehydrating and flushing the body with fluids. There is a certain amount of misinformation regarding tea and rehydration; it is a popular belief that the caffeine in tea creates a diuretic effect, and actually dehydrates the body. According to a 2001 study by Maughan and Griffin entitled, Tea Drinking And Fluid Balance: A Review, the authors found that tea consumption did not produce a net diuretic effect unless the caffeine equivalent of six or seven cups of tea was consumed in one sitting.
Whatever the tea that fits your personality, keep drinking to stay one step ahead of the cold and flu season!
Friedman, Mendel. Overview of antibacterial, antitoxin, antiviral, and antifungal activities of tea flavonoids and teas. Mol. Nutr. Food Res. 2007, 51, 116 – 134.
Jae-Min Song, Kwang-Hee Lee, Baik-Lin Seong. Antiviral effect of catechins in green tea on influenza virus. Antiviral Research 68 (2005) 66-74.
Matsumoto et al. Effects of Green Tea Catechins and Theanine on Preventing Influenza Infection among Healthcare Workers: A Randomized Controlled Trial. BMC Complementary and Alternative Medicine 2011, 11:15.
Yamada H, Takuma N, Daimon T, Hara Y. Gargling with tea catechin extracts for the prevention of influenza infection in elderly nursing home residents: a prospective clinical study. J Altern Complement Med. 2006 Sep;12(7):669-72.
EJ Gardner, CHS Ruxton and AR Leeds. Black Tea - helpful or harmful? A Review of the Evidence. European Journal of Clinical Nutrition (2006), 1–16
Park, Mijong et al.Green Tea Consumption Is Inversely Associated with the Incidence of Influenza Infection among Schoolchildren in a Tea Plantation Area of Japan. J. Nutr. October 1, 2011 jn.110.137547