Green Tea: A Winter Tonic

If you are trying to do everything you can to prevent colds and flu this winter, it might be time to add green tea to your list. A new study found that taking a green tea extract reduced the number of sick days and the severity of cold symptoms.

Tea is made from the leaves of the tea bush, Camellia sinensis. Once the leaves are picked, an oxidation process called fermentation begins naturally. Fermenting leaves form tannins, and varying degrees of fermentation result in different flavors and colors. Black tea is completely fermented and has the most tannins of all teas, while oolong tea is slightly less fermented. Green tea is minimally fermented, so many of the antioxidant nutrients in the tea leaves are preserved.

Green tea is a popular beverage in Asian cultures, where many people drink eight or more cups per day. It has become increasingly popular in the West, owing in part to reports of its health benefits, such as preventing heart disease and cancer. Studies have suggested that the powerful antioxidants in green tea can stimulate the immune system and improve the course of a number of chronic diseases.

The new study, published in the Journal of the American College of Nutrition, looked at the effect of a green tea extract on the occurrence and severity of the common cold. The study included 118 healthy adults who took one capsule of green tea extract or placebo twice per day for three months during the flu season. The decaffeinated green tea extract contained standardized amounts of two immune-activating plant components: L-theanine and epigallocatechin gallate (EGCG).

Throughout the study, the people kept a daily log of cold and flu symptoms including fever, runny nose, stuffy nose, sore throat, cough, headache, diarrhea, and nausea. Compared with placebo, 32.1% fewer people in the green tea group experienced any cold and flu symptoms. Green tea users reported 22.9% fewer illnesses lasting two or more days, and only 5.7% of them sought medical care, compared with 12.7% in the placebo group.

The study’s authors noted that the degree of symptom prevention observed in this study could have an enormous impact on public health. “Cold and flu symptoms can be perennial sources of misery and lost productivity for most healthy adults, and the introduction of a safe, effective, and natural capsule that can prevent such symptoms represents a significant breakthrough in preventive medicine.”

To sidestep the cold and flu, many doctors recommend that you eat lots of fruits and vegetables, avoid sugar, get plenty of sleep, wash your hands frequently, gargle with plain water twice a day, and take 1 to 4 grams of vitamin C each day. So now you might also consider drinking a lot of green tea—or supplementing with a green tea extract, such as the one used in this study, estimated to contain as much L-theanine and EGCG as about ten cups of tea. Because green tea has caffeine (between 15 and 50 mg, depending on how it is prepared), people who are sensitive to caffeine should look for decaffeinated green tea.

November 8, 2007; (J Am Coll Nutr 2007;26:445–52)

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Maureen Williams, ND, received her bachelor’s degree from the University of Pennsylvania and her Doctorate of Naturopathic Medicine from Bastyr University in Seattle, WA. She has a private practice in Quechee, VT, and does extensive work with traditional herbal medicine in Guatemala and Honduras. Dr. Williams is a regular contributor to Healthnotes Newswire.

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