Green Tea May Combat Rheumatoid Arthritis

Antioxidants may reduce the severity of RA symptoms

Green tea, and other varieties of tea from the Camellia sinensis plant, may have health benefits that include preventing and treating rheumatoid arthritis (RA). This is believed to be due to the antioxidants it contains—specifically, catechins. Polyphenols like catechins stabilize molecules that have become unstable for a variety of reasons. These unstable molecules are called free radicals, and they're implicated in all kinds of diseases—including RA.

How Green Tea Catechins Help RA

Two catechins in green tea have been found to interfere with the body's natural inflammatory processes: EGCG (epigallocatechin 3-gallate) and EGC (epicatechin 3-gallate). Of these, research has shown EGCG to be the most effective of the two. EGCG also appears to have better bioavailability, meaning your body is able to absorb and use it.

The bulk of green-tea research has focused on EGCG. A paper published in Arthritis Research & Therapy called EGCG "one of the leading plant-derived molecules studied for its potential health benefits." According to the researcher, EGCG constitutes up to 63% of the total catechins in green tea. As an antioxidant, it's between 25% and 100% more potent than vitamins C and E.

Synovial Fibroblast Activity

The focus of some research has been synovial fibroblast activity (synovial meaning having to do with the joint lining, fibroblast meaning a cell in connective tissue that produces collagen and other important fibers).

In RA, synovial fibroblasts are produced at high levels and destroy the cartilage around joints. This can increase the pain and disability of the disease.

The surge in fibroblasts is theorized to be caused by several kinds of cells known to be important parts of the overactive immune system in RA, including tumor necrosis factor-alpha (TNFα) and interleukin-1beta (IL-1ß).

These excess fibroblasts then influence the activity of immune cells—leukocytes, cytokines, and chemokines—via specific types of signaling. That allows the fibroblasts to invade the cartilage and begin destroying it. Some scientists believe the fibroblast signaling process may be a valuable target for future drugs.

This idea is backed by a review of natural products for treating autoimmune arthritis that came out in 2018. It cites a rat study in which green tea significantly reduced levels of TNFα and IL-1ß. It also decreased the activity of certain chemokine receptors in the joints.

A 2017 study of RA fibroblast signaling used human synovial tissues from the knees and hips during joint replacement surgery or other surgical procedures. They found that both EGCG and EGC inhibited IL-1ß-induced production of interleukins 6 and 8, but that EGCG did it more effectively.

Other Benefits for RA

Other laboratory research has noted that:

  • EGCG appears to impact several types of T cells, which are also part of RA's immune over-response. 
  • Green tea may normalize metabolic functions that tend to be abnormal in arthritis.
  • In addition to catechins, green (and black tea) contains an amino acid called L-theanine, which has numerous health benefits for stress, mood, and sleep (in general, not just for RA).

Research on Dietary Use

A large-scale, real-world study released in 2020 looked at the association of RA and tea consumption, including green and black teas. Researchers analyzed data from more than 700 participants and concluded that people who had a high intake of tea had less RA disease activity than people who had a low tea intake or didn't drink tea at all.

This trend was strongest in women, non-smokers, and people over 60 years old. They concluded that tea does appear to have a beneficial effect on RA.

A a review of literature on dietary influences in RA, which was also published in 2020, found evidence that:

  • Black tea had an anti-inflammatory effect and decreased levels of several markers of RA, including CRP levels, the aggregation/activation of leukocytes and platelets
  • More than three cups of tea per day reduced the risk of developing RA.
  • Green tea had protective effects against inflammatory diseases like RA, as well as cardiovascular diseases, neurodegenerative diseases, and some types of cancer.

Furthermore, a 2018 study including a thousand participants concluded that green tea and coffee both appeared to help prevent the development of RA.

Green Tea vs. Other Teas

Green, white, and black teas all come from the Camellia sinensis plant. The only difference between them is when the leaves and buds are harvested. Earlier harvesting results in white, a little later results in green, and later still results in black.

The earlier the harvest, the higher the level of antioxidants and lower the level of caffeine. In fact, animal studies have shown the anti-inflammatory effect of green tea extract to be superior to that of black tea extract.

Green, black, and white teas come in different varieties. Because they're all from the Camillia sinensis plant, they contain the same polyphenols, although the amounts may differ. Some of these varieties are:

  • Jasmine (green)
  • Matcha (green)
  • Oolong (harvested between green and black stages)
  • Assam (black)
  • Ceylon (black)
  • Chai (a blend of tea and spice, usually made with black tea)
  • Pu-erh (a naturally fermented variety harvested even later than black tea)

Of note, herbal teas (also called tisanes or herbal infusions), rooibos, and honeybush teas do not come from the Camellia sinensis plant. While some of them may offer health benefits, they don't contain the same polyphenols or have the same effects as the varieties above.

Dosage and Intake

Several studies recommend dosages of EGCG between 90 milligrams (mg) and 300 mg a day. Since a cup of green tea contains between 60 mg and 125 mg, you can get the target amount in a few cups a day. Research suggests that doses of up to 800 mg a day may be safe; however, side effects are more likely at this level.

Research suggests that green tea extract is more effective when taken on an empty stomach.

But it's difficult to determine the specific amount of catechins you're getting from any particular tea. If you want a consistent therapeutic dosage, you may want to look into green tea extract supplements.

Side Effects and Warnings

Even natural products can cause side effects, so any time you add something medicinal to your regimen, you should know the potential side effects and watch for any that may crop up.

It's also important to talk to your doctor before taking anything, as it may not be safe for you based on your medical history or may interfere negatively with other treatments.

Possible side effects of green tea, which tend to be more common at higher dosages, mainly include those caused by the caffeine it contains. They include:

  • Anxiety
  • Tremors
  • Irritability
  • Trouble sleeping

However, green tea is less likely than other caffeinated beverages to cause these symptoms. If you're sensitive to the effects of caffeine, you may want to look for decaffeinated options.

Liver toxicity has been noted in animal studies, but only at doses that far exceed recommended human intake. Still, if you have liver disease, talk to your doctor about the potential risks of green tea.

Little is known about the impact of green tea consumption during pregnancy and lactation. One animal study suggests that it may cause metabolic changes in both the mother and baby that may lead to abnormal deposits of fatty tissue. The caffeine in green tea may also be a concern. If you're pregnant, trying to get pregnant, or breastfeeding, talk to your doctor about green tea before using it.

Tannic acid in green tea may stain teeth.

Drug Interactions

Green tea may cause other medications to work differently than they're intended. It may lessen the effects of:

  • Corgard (nadolol) for blood pressure and heart disease
  • Blood thinners, due to the tea's vitamin K content

Because of the stimulating effect of green tea, you shouldn't combine it with other stimulants.

Selecting and Brewing Green Tea

If you're looking for a quality green tea to brew, avoid tea bags from the average grocery store. They tend to be lower quality and not as fresh as other teas. Places to find better quality teas include:

  • Local tea shops
  • Higher-end grocery stores or specialty markets
  • Asian grocery stores
  • Online tea shops and vendors

You may be able to find high-quality tea bags, but you'll typically get the best results using loose-leaf teas.

It's hard to gauge the medicinal value, if any, of pre-bottled tea. You likely won't be able to get information on tea quality, steep time, or catechin levels. You may also be consuming large amounts of sugar and carbohydrates along with numerous other ingredients. For medicinal use, brewing your own or using supplements are probably better choices.

To Prepare Green Tea

Brewing your green tea properly is important to getting the maximum benefits it can offer.

  • Use water that is simmering, not boiling (between 150 and 180 degrees F is ideal)
  • Follow the steep time for the variety you get (if noted). Generally, green teas have a short steep time—somewhere between 20 seconds and four minutes.

Buying Green Tea Supplements

Remember that supplements are not regulated by the U.S. Food and Drug Administration (FDA). Always be sure to read the labels on any supplements you buy. That will tell you the strength of the product you're getting along with any additional supplements and inactive ingredients it contains.

To make sure the green tea supplement you purchase contains the amounts of catechins and caffeine listed, look for a seal of approval from a third-party testing organization. ConsumerLab is a common one. That lets you know the label is accurate and the product isn't contaminated in potentially harmful ways.

A Word From Verywell

Antioxidants are beneficial substances found not just in green tea, but in all plants and animals—including humans. Polyphenols are found in certain plants, including apples, grapes, olives, cocoa beans, grains, legumes, and spices like turmeric—as well as green tea. Eating a diet high in antioxidants can have myriad benefits for RA and beyond.

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