Since ancient times, green tea has been considered by traditional Chinese medicine as capable of improving various ailments. Recent studies suggest green tea has a beneficial effect on some cancers, cardiovascular disease, diabetes, Parkinson's disease and Alzheimer's disease. Can green tea help to protect against Autoimmune diseases?
Polyphenols in green tea
Tea whether it is oolong, black or green comes from the plant Camellia sinensis. Green tea is unfermented, whereas the processes used in the manufacture of black tea may decrease levels of polyphenols known as catechins.
The most abundant and biologically active catechin in green tea is called epigallocatechin-3 gallate (EGCG). EGCG has been studied extensively to have the following benefits:
antioxidant
anti-inflammatory
anti-fibrotic
anti-microbial
anti-viral
immuno-modulatory
neuro-protective
gut-protective
How does green tea help in Autoimmune diseases?
EGCG in green tea has been suggested to have potential protective effects in Autoimmune diseases. However, most of the evidence is from animal studies so far. Some of the underlying Autoimmune mechanisms studied to date suggest EGCG:
Inhibits B cell proliferation.
Inhibits neutrophil recruitment to inflammation sites.
Inhibits production of pro-inflammatory molecules in monocytes/macrophages.
Inhibits antigen-specific T cell proliferation and T cell differentiation.
Suppresses Th1 and the proinflammatory Th17 cells.
Inhibits proinflammatory cytokines IL-6, IL-17A, IL-1β and TNF-alpha.
Stimulates production of regulatory T cells which support immune tolerance.
Suppresses proliferation of auto-reactive T cells in Autoimmunity.
Regulates signalling pathways such as the inflammatory NF-kB pathway .
The following Autoimmune diseases have seen benefits with EGCG intake in both animal and human studies:
Rheumatoid arthritis - various studies detail the effects of EGCG in animal models reducing the onset and progression of arthritis. Consumption in rheumatoid arthritis patients, showed reduction in disease activity and pain scores.
Inflammatory bowel disease - in one study, less severe colitis and reduced levels of inflammation markers in the colon and circulation were seen.
Sjogren's syndrome - significantly less salivary gland damage was seen in a group treated with green tea extract.
Type 1 diabetes - in a study using mice as a model, EGCG delayed the onset and progression of type 1 diabetes. Epidemiological studies also reveal that Chinese and Japanese populations, who consume a lot of green tea, show the lowest incidence of type 1 diabetes in the world.
Multiple sclerosis - mouse models for human multiple sclerosis given EGCG, reduced their clinical symptoms, brain pathology and pathological immune responses.
Systemic Lupus Erythematosus - EGCG suppresses the inflammatory cytokine TNF-alpha in the Systemic Lupus Erythematosus model.
Is green tea suitable for everyone with Autoimmunity?
Although green tea has been recognised for its many benefits, it may not suit some individuals. Firstly, it contains caffeine, so those who do not tolerate caffeine due to compromised liver detoxification, are not advised to drink more than they can tolerate. This is especially important for matcha green tea which is known to be higher in caffeine.
Secondly, green tea can can polarise the immune system's T helper cells to be more TH2 dominant. Therefore, Autoimmune patients who have an imbalanced immune system towards TH2, may not be advised to drink excessive amounts of green tea.
Thirdly, green tea may not be suitable to take with some medications, since green tea may interfere with their effectiveness. Furthermore, green tea has been known to interfere with iron bioavailability. It is good to consult with a health professional in these circumstances.
Finally, excessive amounts of green tea may be toxic in humans. A better knowledge of the toxicity at a higher dosage needs to be determined through further studies. Therefore it is recommended to drink green tea within moderation.
How to consume green tea?
It’s best to let green tea leaves or tea bags steep in hot water for three to five minutes. Adding other antioxidant herbs and spices such as ginger, turmeric, rosemary, mint or even lemon may add to the taste.
Matcha green tea is a concentrated powdered form of green tea, carefully produced using the entire leaf and therefore retaining higher levels of catechins and antioxidants. Besides brewing matcha powder into tea as per the packet instructions, you can also add it to baking recipes, smoothies, breakfast bowls, lattes and desserts.
If you’re considering taking green tea supplements, it is probably best to talk to a health professional, to understand dosages and any risks involved.
Can green tea protect against Autoimmune diseases?
Overall the current research suggests that green tea and its bioactive polyphenols may certainly have some preventive or healing potential in Autoimmune conditions. However, more human studies are needed to validate these findings further.
In Autoimmunity, it is always important to take a personalised approach. If tolerated by the individual, green tea in moderation, may be a healthy addition to a balanced, nutrient dense, anti-inflammatory diet.
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