Green tea helps fight the flu

Roman Bystrianyk, "Green tea helps fight the flu", Health Sentinel, November 29, 2005,

Each year there is a mounting fear as the flu season approaches. With much of the attention given to the avian flu this year, the level of anxiety has increased in many people. With these concerns there is an interest in finding alternatives that can help fight the flu.

Several studies show that green tea – in particular chemicals called polyphenols – decrease the infectivity of the influenza virus. A study conducted at Pace University indicated that green tea extracts and polyphenols have an adverse effect on bacteria that cause strep throat and other infections. Milton Schiffenbauer, PhD, a microbiologist and biology professor at Pace University in New York City, stated in a news release that, “Our research shows tea extracts can destroy the organism that causes disease. If we can stimulate the immune system and at the same time we are destroying the organisms then it makes sense to drink more tea.”

Green tea is produced from the leaves of an evergreen plant called Camellia sinensis. The major active ingredient in green tea is believed to be the polyphenol compounds called catechins. These key compounds include EGCG, EGC, and ECG.

A study in the August 2005 journal Antiviral Research, examines these compounds against three currently circulating influenza viruses. The authors performed a number of experiments to examine the effects of green tea on these flu strains.

They found that these compounds were effective in reducing the plaque forming capabilities of the viruses. A plaque is produced when a virus infects a cell, replicates, and then kills that cell. EGCG and ECG at 50 μM (micromolar) inhibited more than 50% of the plaque forming ability of the influenza viruses. However, when all the polyphenols were combined the mixture reduced the plaque forming by over 90% and in the case of one flu strain (A/Chile/1/83 – H1N1) by nearly 100%.

Other experiments showed that the greater the concentration of green tea polyphenols the more of the flu virus was inhibited. “The results suggest that the antiviral effect is exerted not only in the initially infecting viruses but newly propagated viruses as well.”

After drinking 1 cup of tea, the maximum blood concentration of EGCG in humans reaches 60 micromoles in adults weighing 60 kg (132 pounds). Some authors recommend as many as 10 cups of green tea per day to achieve green tea’s optimal benefits, although the study authors caution that this study was done outside the human body and should be interpreted with some caution.

The author’s emphasize that the “total tea extract” was much more effective than any single of the green tea polyphenols that were tested in isolation. They note that, “dietary uptake of tea would be beneficial for direct intervention of influenza virus infection.”

SOURCE: Antiviral Research, August 2005