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  • Writer's pictureDr. Nada Milosavljevic


As we enter cold and flu season, it’s time to strengthen our immune systems to face the onslaught of sniffles, coughs and sneezes. Research shows that tea possesses compounds which can enhance the immune system and offer added defense against illnesses that tend to occur more often this time of year. These compounds include catechins (a chemical found in plants, especially green tea), amino acids (important in building proteins that help the immune system) and polyphenols (an antioxidant).

Fighting Viruses

Influenza – one of the most common infections – poses a serious health problem. In a typical year, this virus can affect 10-20% of the U.S. population. Catechins, found in green tea, have antiviral properties. Research evaluating green tea catechins found that they exert multiple effects to reduce influenza infection.

One 2006 study had patients gargle with green tea to determine whether this may prove to be a cost-effective way to curb upper respiratory infection. This clinical study measured the effectiveness of a green tea throat rinse in 124 elderly residents in a Japanese nursing home. Participants gargled with a green tea solution three times per day for three months. Those who used the rinse had a significantly lower incidence of the virus. Other studies examine green tea in the form of extract capsules and as a hand wash. Both forms demonstrated positive antiviral effects.

Children also appear to reap immune benefits from tea. In 2011 Japanese scientists examined the effects on 2,600 children who consumed several cups of green tea each week. The children who drank five cups of green tea per week had significantly fewer sick days from school. Even those who drank one cup per day reaped positive benefits.

Catechins and the amino acid theanine both appear to support immune function. While tea contains many healthy compounds, these two particular complexes found in tea bolster T-cell function to fight viruses (as well as autoimmune disorders). Current research focuses on one of tea’s catechins, EGCG (epigallocatechin gallate). EGCG is a biologically active compound that shows many effects on numerous cellular systems. An animal study conducted in 2011 found that EGCG increased the production of regulatory T-cells in the spleen and lymph nodes. While the response was not as robust as some medications, EGCG also invites less concerns about side effects and toxicity.

Fighting Bacteria

Tea research also observes antibacterial properties. Bacteria are another immune system invader that can wreak havoc on our bodies, and cause infection and illness. In 2007, a study looked at the most common bacterial microbe linked to dental cavities, Streptococcus mutans, and whether polyphenols, present in tea, played a protective role in oral health. The results showed that polyphenols made for a less hospitable environment to the bacteria, and reduced its ability to adhere and grow.

In 2013, Pharmacognosy Review published research that conducted a thorough review of studies specific to cavity prevention and oral health. This literature review determined that tea can play a supportive role to help curb dental caries. In both studies, green tea polyphenols appear to be effective against Streptococcus mutans, and provide some protection to impede its growth and adherence in the oral cavity. A more recent study suggests that black tea can also be helpful in mitigating periodontal disease.

Possibilities in Gene Therapy

Tea and its immune implications have also caught the attention of genetic researchers. An area of genetic science called epigenetics now focuses on EGCG’s potential to affect gene expression. Epigenetics evaluates the mechanisms that do not alter the underlying DNA code, but affect downstream gene expression. EGCG may be a compound that promotes the expression of certain genes and signals what cells get turned “on” and “off.” In this way, immune cell production may be altered, triggered or decreased. This is one theory regarding how tea, through EGCG, might affect T-cell production and the immune response.

Tea may prove to be a tasty, cost-effective, whole-food approach to enhancing immune health. While more human studies need to be conducted to make conclusive statements about tea’s connection to immune function, there appears to be positive benefit from tea against a host of bacteria and viruses. Seems like a tasty way to protect yourself from bacteria and the flu may be right in your tea cup.


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