EGCg in green tea inhibits flu infection

Joint research conducted by the Central Research Institute of ITO EN, Ltd. and Professor Takashi Suzuki of the School of Pharmaceutical Sciences, University of Shizuoka, showed that epigallocatechin gallate (EGCg), a kind of catechin contained in green tea, had an inhibitory effect against three types of influenza viruses, including the swine-origin H1N1 virus that caused pandemic flu in 2009, and that its effect did not depend on the type of virus. These findings once again suggest that green tea is effective in preventing flu.

- Background

Influenza viruses are highly contagious and susceptible to mutation. This is why flu spreads repeatedly each year. Recently, the swine-origin, new type of flu (H1N1) has become a pandemic, raising serious concerns. Gargling with green tea has already proved to prevent the onset of seasonal flu. It has become clear that catechin, a major type of polyphenol in green tea, plays a major role in prevention of flu infection, and that, among different types of catechin, EGCg displays the strongest antiviral activity. We conducted examinations to see if EGCg also shows antiviral activity against the new type of H1N1 virus, regardless of viral subtypes. (Patent applications were filled for related matters.)

- Research content

Solutions containing three types of viruses including the H1N1 virus were mixed with EGCg extracted from green tea. The mixture was added to cultured cells, which were thus infected. The cells were incubated for a set period of time, and the number of infected cells was counted. The concentration of EGCg at which virus infection was inhibited to 50% of the level of infection without EGCg was calculated.

- Results

The experiments showed that EGCg prevented flu virus infections at lower concentrations than Amantadine (a drug used to prevent and treat flu). A typical concentration of EGCg in green tea infused from a teapot is reported as 5,000-7,000 micromoles/L. Therefore, these results indicate that green tea diluted 1,000-fold or more is effective to halve infections by three types of viruses, including H1N1.

The study showed that EGCg contained in green tea has potential to inhibit flu infection regardless of its type, and suggested once again that green tea is effective in preventing flu.