Boosting Immunity with Green Tea

If you like to drink green tea, you’re part of a big fan club: it is the most widely consumed beverage in the world. Green tea, the dried leaves of Camellia sinensis, has no known serious side effects. However, recent studies have found that green tea could possibly promote a healthy immune system. This is largely due to the components found in the leaves. They are mainly composed of polyphenols (10–25%), which are naturally occurring antioxidants. Antioxidants have been getting a lot of attention recently because they have been found to play a role in preventing serious diseases, like cancer and osteoporosis. The main polyphenolic compounds in green tea (epicatechin (EC), epigallocatechin (EGC), EC-3-O-gallate (ECG), and EGC-3-O-gallate (EGCG) possess anti-inflammatory and anti-carcinogenic properties [1,2,3,4].

Stopping Disease Before It Starts

Oxidants have the potential to damage most kinds of molecules, including DNA. Oxidative stress occurs when too many oxidants override the antioxidant capability of the cell. When this happens. DNA may get damaged, tumor-suppressor genes could mutate, or the cell might die. These harmful events are associated with cardiovascular, neurodegenerative, and carcinogenic illnesses like heart disease, Azheimer’s or lung cancer. Not surprisingly, an improved antioxidant defense decreases the chance of getting these kinds of illnesses. Consuming green tea directly affects the body’s immune system, since its compound EGCG is known to be a very potent antioxidant [5]. Current studies show that using green tea as a dietary supplement can aid in preventing certain diseases. It is especially effective for cardiovascular disease and other ailments in which oxidative stress and inflammation are the main causes.

Immune System Basics

Immunity is the ability of an organism to fight against any abnormal function occurring in the body. The immune system prevents infections and diseases by handling dangerous cells found in the body. Organs like the spleen and thymus are part of the immune system. Lymph nodes and bone marrow also help the immune system function properly by making and storing specific immunity cells. All cells of the immune system originate from a special stem cell in the bone marrow. This stem cell gives rise to two major kinds of progenitor cells (cells that create only specific kinds of cells): the myeloid progenitor cells and the lymphoid progenitor cells. These two kinds of cells create a big family of cells that are used by the body in both the innate (non-specific) and adaptive (specific) immune systems. For example, myeloid cells create large white blood cells (monocytes) and macrophages, cells that are activated by inflammation. Lymphoid cells make natural killer (NK) cells, which fight infection. The organs and cells of the immune system are directly impacted by food consumption, since a healthy diet brings in the fuel for proper operation.

Soothing the Inflamed, Stimulating the System

Green tea enhances the immune system’s cells and fluids, decreasing the risk of certain cancers and cardiovascular diseases [6]. The polyphenols in green tea promote the immune system’s disease-fighting properties with no harmful side effects. Animal studies also bear testimony to the immunity-boosting power of green tea. Mice with arthritis that consumed green tea polyphenol extract had a lower incidence of the disease as well as a less severe form of it [7]. The extract has also been shown to reduce the symptoms of certain autoimmune diseases like Sjogren’s syndrome, which causes a dry mouth and eyes (among other symptoms). Another component in green tea extract, tea polysaccharide (TPS), stimulates the immune system. It has been reported that the TPS from immature leaves was better at stimulating the immune system than that from mature leaves (its ability depended on the content of the strictinin, an antiviral chemical, in the leaf extract) [8]. Notably, the researchers tested a mixture of catechin and TPS without polyphenols; they found that this mixture did nothing to further enhance the immune system. This shows that these compounds need to work in concert with polyphenols in order to have a beneficial effect.

Green Tea: Stimulating in Many Ways

While green tea has typically been viewed simply as a popular drink, it has become clear that its advantages go beyond quenching our thirst. The anti-inflammatory and antioxidant potential of green tea have been demonstrated in a variety of studies. Researchers are now examining green tea and its constituents to determine their effectiveness in disease prevention and management. Green tea may be a safe and effective nutraceutical treatment for a variety of illnesses and ailments.

References

1. Katiyar SK, Mukhtar H. Tea consumption and cancer. World Rev Nutr Diet. 1996;79:154–84.

2. Graham HN. Green tea composition, consumption, and polyphenol chemistry. Prev Med. 1992;21:334–50.

3. McKenna DJ, Hughes K, Jones K. Green tea monograph. Altern Ther Health Med. 2000;6:61–8, 70–2, 4 passim.

4. Arab L, Il’yasova D. The epidemiology of tea consumption and colorectal cancer incidence. J Nutr. 2003;133:S3310–8.

5. Salah, N., Miller, N. J., Paganga, G., Tijburg, L., Bolwell, G. P. and Rice-Evans, C. (1995). Arch. Biochem. Biophys. 322:339–46.

6. Klein, C., Sato, T., Meguid, M. M. and Miyata, G. (2000). From food to nutritional support to specific nutraceuticals: a journey across time in the treatment of disease. J Gastroenterol. 35:1–6.

7. Haqqi, T. M., Anthony, D. D., Gupta, S., Ahmad, N., Lee, M. S., Kumar, G. K. and Mukhtar, H. (1999). Proc. Natl. Acad. Sci. U.S.A. 96:4524– 29.

8. Monobe M, Ema K, Kato F, Maeda-Yamamoto M. J. Agric. Food Chem. 2008, 56, 1423–1427