Green tea leaves contain catechins and other substances such as theaflavins, quercetin, theanine, gallic acid, chlorogenic acid, and caffeine [ 2 ], [ 3 ]. The primary catechin found in green tea extracts is epigallocatechingallate EGCG [ 2 ]. As a significant polyphenol, EGCG has been shown in animal and laboratory studies and clinical trials to have anti-inflammatory and antioxidant properties [ 4 ], [ 5 ].

Due to its properties, it is believed that EGCG may have therapeutic effects on chronic inflammatory diseases such as arthritis, atherosclerosis, and dry eye [ 6 ], [ 7 ].

A study [ 8 ] that examined the effectiveness of green tea extracts in reducing inflammation in eye cells called cornea epithelial cells showed that it could reduce inflammation and prevent cell damage to the cornea.

Interleukin-1β is a cytokine, one of the cells secreted by the immune system, that mediates the inflammatory response [9 ]. Interleukin-1β is critical for the reaction of the human body against pathogens.

However, it can exacerbate damage during chronic disease and lead to tissue injury [ 9 ]. In the study [ 8 ], EGCG inhibited multiple cytokines, including interleukin-1β. This demonstrates that EGCG from green tea extracts may have beneficial effects against corneal inflammatory disease.

In addition, EGCG has also been shown to have beneficial effects against rheumatoid arthritis, another chronic inflammatory disease. Patients with RA experience a limited range of motion, swelling, and redness of the joints.

There is currently no cure for RA. However, treatment strategies may include reducing inflammation to delay the progression of the disease.

A study [ 11 ] discovered that catechins found in green tea extracts interfere with the interleukin-1β IL-β signaling pathway. In the body, IL-β signals the production of pro-inflammatory mediators and Cox-2 in cells called human rheumatoid arthritis synovial fibroblasts FASFs.

So, it appears green tea may reduce the ability of IL-β to signal premature cells lining the synovial joints to produce cells that will lead to inflammation of the joints.

Results [ 11 ] reinforce earlier findings that green tea extracts can potentially reduce inflammation of the joints in those with rheumatoid arthritis. A group of investigators [ 12 ] suggested that unfermented green tea yields the highest catechins level compared to fermented teas.

When set side by side with black tea, green tea has a higher content of catechins. Since black tea is fermented, catechins are oxidized to theaflavins, lowering the content of catechins in the process [ 12]. Since catechins have antioxidant properties, the higher the content of catechins, the greater the antioxidant and anti-inflammatory properties.

Black teas have lower antioxidant and anti-inflammatory properties than green teas. Although green tea remains the best source of catechins, the antioxidant and anti-inflammatory properties may still be uneven. It is reported [ 13 ] that the origin and type of green tea will influence the level of catechins found in its leaves.

How green tea is cultivated and the climate and temperature in which it grows also affect the level of catechins produced in the leaves [ 14 ].

Over the years, Sencha has probably been recognized as the most popular of all the green teas. Sencha is mainly cultivated and produced in Japan [ 15 ].

The quality of the leaf, also known as leaf grade, and the place in Japan where it is grown will influence its taste. Sencha tea, once treated, can be transformed into Matcha, Bancha, and Gyokuro tea species.

Matcha green tea leaf infusion has the highest amount of L-theanine and caffeine compared to Gyokuro and Bancha teas [ 16 ]. On the other hand, infusions of Bancha green tea have lower amounts of caffeine and L-theanine compared to Gyokuro tea infusions [ 16 ].

L-theanine is described as an amino acid involved in the formation of proteins used to produce insulin, adrenaline, and neurotransmitters [ 17 ].

A scientific study [ 1 8] showed that L-theanine could modify the effects of caffeine, especially the stimulant activities of caffeine. The presence of L-theanine results in improved cognitive function, decreased blood pressure, and improved mood and concentration. Antibiotics are lifesaving medications, but they may also pose problems with autoimmune conditions like rheumatoid arthritis.

Infrared saunas may help people with rheumatoid arthritis heal tissue, improve mobility, and reduce pain. There's limited evidence for cryotherapy's effectiveness for RA. However, some people report temporary pain relief and reduced joint swelling.

Joints affected by rheumatoid arthritis may feel tender, painful, and stiff. This can make it challenging to fall and stay asleep. E-stim is often used to target pain and promote muscle recovery, but its benefit to people with RA has not been proven.

Learn more. A Quiz for Teens Are You a Workaholic? How Well Do You Sleep? Health Conditions Discover Plan Connect. Rheumatoid Arthritis. Basics Pain Management Living with RA Mental Health Community Newsletter. Going Green: Green Tea for Rheumatoid Arthritis.

Medically reviewed by Imashi Fernando, MS, RDN, CDCES — By Ann Pietrangelo — Updated on August 2, Green tea Research Other health benefits Preparation Supplements Interactions FAQs Bottom line Green tea contains powerful antioxidants with anti-inflammatory properties.

About green tea. What does the research say? Other health benefits of green tea. How do you take your tea? Green tea supplements. Possible interactions.

Frequently asked questions. The bottom line. Evidence-Based Benefits of Green Tea. How we reviewed this article: Sources. Healthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. We avoid using tertiary references.

You can learn more about how we ensure our content is accurate and current by reading our editorial policy. Aug 2, Written By Ann Pietrangelo.

Medically Reviewed By Imashi Fernando, MS, RDN, CDCES. Dec 6, Written By Ann Pietrangelo. Share this article. related stories Does Green Tea Make You Poop? This hormone helps with insulin sensitivity, inflammation, and fatty acid breakdown [ Despite some potential benefits on the scale, green tea extract is not a miracle weight loss pill.

Evidence shows that by itself, green tea extract does not lead to reductions in key measurements like weight or waist circumference [ Researchers are also exploring the potential benefit of green tea extract for cancer.

Early clinical studies have shown that the polyphenols present in green tea may play an important preventative role in the following types of cancer [ 1. Endometrial cancer: Green tea has been linked to a reduced risk of developing cancer of the lining of the uterus [ 1.

Ovarian cancer: Regularly drinking green tea seems to reduce the risk of ovarian cancer [ 1. Researchers also believe that polyphenols may help kill cancerous cells and stop them from growing.

For example, laboratory studies have found that green tea extracts prevent the growth of prostate cancer cells in test tubes. Still, more research is needed to explore whether these benefits can be replicated in a clinical setting and whether green tea extract has any treatment benefit [ 3.

While these results seem promising, much of the research has involved green tea drinkers, not supplements, and many other studies have produced conflicting results. More research is needed to explore green tea's potential anti-cancer benefits, specifically using green tea extract.

For example, some green tea supplements contain only dry green tea leaves, while others contain isolated forms of one or more polyphenols, like EGCG. Supplements made with isolated antioxidants will be more potent and potentially provide more significant benefits.

Whether it contains EGCG: You will find antioxidants listed as polyphenols, catechins, or EGCG on a green tea supplement label. Since EGCG is the most widely researched green tea antioxidant and is closely linked to its health benefits, you should look for a supplement that contains this polyphenol [ 2.

How much caffeine the supplement contains: Green tea extract supplements can contain vastly different amounts of caffeine, from zero to mega doses of mg or more. At Elo, we provide science-backed personalized smart supplements. We also offer dietitian support with our Elo Health coaches so you can stay accountable, reach your goals, and better understand your health.

Get your personalized supplements started today! Green tea extract supplements come in liquid, powder, and capsule form and are typically standardized to the amount of polyphenols or antioxidants they provide [ 1.

If you like the taste of green tea, you can dilute green tea extract liquid in a glass of water and blend green tea extract powder into smoothies.

While green tea supplements are generally well tolerated, consuming large doses of green tea extract can increase the risk of side effects due to the caffeine content [ 1. Green tea extract also contains a chemical linked with liver injury when used in high doses [ 1.

If you suddenly stop using green tea extract, you may experience caffeine withdrawal symptoms, such as headaches, irritability, and nervousness.

To help prevent withdrawal, lower your dose slowly. Withdrawal is more likely if you have used green tea extract for a long time or in high doses [ Consult your doctor or pharmacist before taking green tea extract if you have any of the following conditions [ Here are some other things to keep in mind before adding green tea extract to your routine.

Green tea catechins, primarily EGCG, have been shown to inhibit iron absorption. To avoid this, consider taking green tea supplements two hours before or after eating iron-rich foods like meat, poultry, shellfish, beans, tofu, and fortified breakfast cereals.

You can also reduce this interaction and enhance iron absorption by pairing your plant-based iron-rich foods with vitamin C [ 2. Green tea has been shown to reduce blood levels and the effectiveness of certain blood pressure and heart medicines at high doses.

Consult your healthcare provider before taking high doses of green tea extract [ If you are pregnant, consult your doctors about the risks and benefits of green tea extract supplements before taking them. As previously mentioned, most green tea supplements contain caffeine, and it is recommended that women limit caffeine during pregnancy.

This product may also decrease folic acid, and low levels of folic acid are associated with an increased risk of neural tube defects [ Toxicity can occur from very high doses of green tea extract.

In humans, the maximum tolerated dose is around 4. For example, for someone who is 5 feet 10 inches tall and weighs pounds, acute toxicity would occur at a daily dose of 7. While you may experience benefits sooner, many studies have shown green tea extract benefits in as little as weeks of supplementation [ 2.

Green tea extract comes from the leaves of the Camellia sinensis plant. For green tea, young leaves of the plant are harvested, withered, steamed, or pan-fried, then dried. This process preserves many beneficial compounds in green tea, which can then be extracted and consumed as a supplement.

Green tea extract often has caffeine. Up to mg of caffeine daily appears safe for most healthy adults [ If you prefer to avoid caffeine, decaffeinated green tea supplements contain little to no caffeine.

Green tea extract is a highly concentrated form of green tea that contains potent antioxidants.