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Xenohormesis & Immunity

Updated: Nov 17, 2020

Harness the stress of plants for your own immune benefit. Learn about the antiviral and anti-inflammatory benefits of green tea...


The human population currently sits at around 7.8 billion people, making us a fairly successful species from that standpoint. But it is worth noting that in nature, most animal populations are routinely kept in check when they reach a certain critical mass by lack of food, predation, and microbial infection. Pathogens, like any other organism, are trying to assert their evolutionary dominance, just like we are. If we are going to remain healthy in a changing environment, then we need to utilize all resources at our disposal to reinforce our innate immune defense mechanisms. Sound scary? Nature is a contest of forces at all times, but we are also part of nature and we can strive to be the best version of ourselves, physically and mentally, to ebb and flow with life.


The current epidemic of the Wuhan Coronavirus (2019-nCoV) is the largest outbreak of its kind in recent years, concentrated in the Hubei province of China, but now spread throughout much of the world. SARS (severe acute respiratory syndrome) and MERS (Middle Eastern respiratory syndrome), in 2002 and 2012, respectively, were also caused by related coronaviruses (Tesini, 2018). This family of viruses are enveloped, single-stranded, positive-sense RNA; they are widespread throughout nature, infecting birds and mammals (Hussein and Gallagher, 2010). The most recent iteration of this virus is still running its course and appears to be extremely contagious through fluid droplets that land on mucus membranes. The world’s researchers have raced to sequence the viral genome, but there is still much we do not know about it. Although this may or may not seem relevant to you, it is a stark reminder that all things evolve, including pathogens. Even the common cold or flu takes its toll on the world population each year. As these microorganisms adapt, so must we all. The importance of quality nutrition cannot be underestimated to bolster our innate immune response. You are what you eat…


Humans have always relied on the power of plants to boost our own physiological responses to stress. The phenomenon of “xenohormesis” is the technical term for this, defined as the “biological principle that explains how environmentally stressed plants produce bioactive compounds that can confer stress resistance and survival benefits to animals that consume them” (Hooper et al, 2010). In other words, when a plant’s environment changes, since the plant cannot get away, it instead produces various compounds as part of its own stress response. A common example are grapes and olives grown in hotter and more arid conditions, which are micro (or “hormetic”) stresses to the plant. The wine and oil rendered from these plants will have a higher polyphenol content than if they were grown in cooler and moister environments; resultantly, these polyphenols will confer their antioxidant effects to those that consume them. The same concept is true for the tea plant, Camellia sinensis, which is used to make matcha. Green tea, including matcha, is from tea plants in their mature yet non-roasted and non-fermented state. The specific combination of altitude, shade and humidity result in specific plant characteristics. For example, more direct sunlight will result in more catechin (a tea polyphenol) production as an antioxidant for the plant. More shade will result in more chlorophyll production (rich in magnesium and also an antioxidant) as the plant tries to make the most of the limited sunlight. Both are examples of phytochemicals that serve an adaptive benefit to the plant, but also an additional secondary benefit to us when we consume them. What an elegant concept!


When it comes to the immune-boosting properties of tea, there is a large amount of research supporting the benefits to us from various phytochemicals, broadly categorized as polyphenols, and subdivided into flavonoids and further into catechins (Reygaert, 2018). There are four main catechins that occur in green tea: epicatechin (EC), epicatechin-3-gallate (ECG), epigallocatechin (EGC), and epigallocatechin-3-gallate (EGCG). Most of the research has been done on EGCG (Reygaert, 2018). It has shown anti-inflammatory and anti-cancer properties, as well as anti-microbial properties. EGCG has been shown to have various anti-viral effects against several different types of viruses, including influenza, HIV, Epstein-Barr, Herpes, Hepatitis B and C, and Human T-cell lymphotropic virus type 1 (Tran, 2013). These mechanisms can happen at various stages of the infection cascade, from interfering with viral adhesion to the cell membrane, to interfering with transcription and translation of viral proteins (Xu et al, 2017).

EGCG appears to be the most potent catechin against viruses. Its chemical structure is unique in that it has both pyrogallol and galloyl groups, which seem to be essential for its ability to interfere with viral replication (Xu et al, 2017). In addition to direct hinderance of viral activity, EGCG has been shown to work epigenetically in our own genome by upregulating genes that enhance the immune response. For example, EGCG has been show to increase numbers of regulatory T cells found in the spleen and lymph nodes of mice (Wong et al, 2011), which are essential to a healthy immune response that modulates activity without overshooting into autoimmunity.


The above properties are shared in all quality green teas. One of the things that makes matcha unique is the presence of a full spectrum of phytochemicals that not only boost immune function, but also boost your mood and have elevating flavor. The high level of L-theanine from the shade-grown environment, which confers the steady energy and “feel good” mood that this tea is known for, along with the delicate sweet flavor from the carefully picked leaves, makes drinking your matcha that much more enjoyable. We could go on and on about the specific health benefits it boasts, but it is important to remember that part of the power of ritual is not only the biochemistry alone, but in the perspective and mindfulness that you put into it. Carving out space, intentionally putting nutrition into your body, and knowing there is a vast database of knowledge supporting it, all synergize into a fortifying practice for your morning (or anytime!). Flu (and Corona?) season is still at hand, but you can be confident that drinking matcha daily, in addition to your other healthy practices, will give you a fighting chance to adapt alongside the microbes and be a more resilient human being!

© Sabine Harrington 2020, all rights reserved.

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