Whether drinking, gargling or swallowing an extract in a capsule, green tea is effective at warding off influenza and other upper respiratory tract illnesses.
These are the findings of a new meta-analysis that included a review of the effectiveness of tea gargling and tea catechin consumption in preventing viral infections.
The meta-analysis included six random control trials (RCTs) and four prospective cohort studies.
The research was conducted in Tokyo, and was published in the European Journal of Nutrition in September 2021.
The researchers found that catechins present in green tea inhibit the proliferation of viruses in the upper respiratory tract (URT) by forming “a protective barrier in the pharynx.”
One flavanol in particular, epigallocatechin gallate (EGCG), has a direct anti-viral effect and physically binds to and flushes out viruses in the URT.
“Given the evidence that EGCG, a main component of tea catechins, provides effective protection against influenza virus and adenovirus, it may also protect against respiratory infections caused by other viruses,” the researchers reported.
To conduct the review, researchers utilized published studies from PubMed, Cochrane Library, Web of Science, and Ichushi Web databases. Five of the RCTs the researchers reviewed were conducted in Japan, while one was conducted in the U.S.
Interventions in the RCTs included data from 3,748 subjects who consumed either green tea extracts or bottled green tea. Four of the RCTs used a placebo for the control group, while two RCTs used water.
Thousands of studies – no media attention
Interest in non-pharmaceutical interventions that can fight the spread of infectious disease has increased due to recent pandemics involving influenza and COVID-19.
When research is conducted on non-pharmaceutical interventions such as hand washing, it receives a lot of media attention. However, even though thousands of studies have been conducted on non-pharmaceutical interventions that include herbals, medicinal foods, vitamins and minerals, the data is heavily censored.
One school of thought regarding this unfortunate circumstance is that the media is heavily funded by pharmaceutical companies—companies that see non-pharmaceutical interventions as a threat to profits.
Notwithstanding the censorship, all studies reviewed in the meta-analysis showed a positive benefit. One study demonstrated consumption of catechin capsules reduced the incidence of influenza-like symptoms by 32.1%, while another study noted “strong effects” following consumption of large amounts of catechins per day.
“EGCG and epigallocatechin bind to the hemagglutinin spike on the viral surface and neuraminidase to inhibit attachment of the virus to the cell surface, thereby preventing influenza infection,” the research team wrote.
The findings of this meta-analysis are consistent with previous studies during the past two decades which have demonstrated the robustness of green tea as a potent immune enhancer.
The take-away from the study can be summed up in the researchers’ concluding remark: “Incorporating tea catechin consumption and/or tea gargling into the daily routine may be effective non-pharmaceutical interventions for preventing viral respiratory infections.”
Besides offering protection against respiratory tract infections, green tea is associated with a number of other health benefits. For this reason, green tea—or EGCG from green tea—can be found in several Optimal Health Systems product blends:
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Source: European Journal of Nutrition.