Technically, green tea isn't much different from other types of tea. Its distinct look and taste is a result of the way it's processed.
Green tea is made by steaming fresh leaves of the Camellia sinensis plant at a very high temperature. This process unlocks a class of powerful antioxidants called polyphenols, which account for many green tea benefits. In addition to green tea benefits for digestive health, the polyphenols found in green tea have been shown to have cancer-fighting, anti-inflammatory, and anti-microbial properties.
The consumption of green tea for digestive health dates back thousands of years to its earliest uses in India and China. Today, green tea retains its reputation as an aid for digestion and is available as a drinkable tea or an over-the-counter extract.
How Green Tea May Affect Obesity
Scientific studies demonstrating a direct link between green tea and digestive health are limited. But research performed in other areas provides some insight on why green tea may help digestion.
For example, one recent animal study looked at how one of the polyphenols found in green tea, catechins, may affect obesity. In doing so, these researchers discovered that rats that consumed a diet high in tea catechins had changes in their digestion that were not found in the control group. Rats consuming tea catechins excreted 5.8 percent of the gross energy (calories) consumed versus the 1.6 percent excreted by rats that ate regular diets. They also lost weight and lost some of their stomach fat tissue. The researchers concluded that tea catechins, like those found in green tea, slow down the actions of digestive enzymes. This slowdown means that the intestines aren’t absorbing all of the calories eaten — so the body isn’t gaining weight.
Possible Anti-Inflammatory Effects of Green Tea
Other studies on green tea catechins have uncovered evidence that anti-inflammatory effects may be another green tea benefit. Researchers from the University of Cincinnati College of Medicine recently looked at how a green tea catechin known as epigallocatechin-3-gallate (EGCG) may help in cases of colitis, an inflammatory disorder that disrupts digestive health. They found that EGCG may hamper the signaling pathways involved in colitis inflammation.
Additional research on ulcerative colitis and Crohn’s disease supports these findings on green tea benefits in cases of inflammatory bowel disease (IBD). Green tea has been, and continues to be, studied extensively for its effects on certain types of cancer, effects which may have an indirect application to green tea for digestive health. Since IBD patients are at increased risk for colon cancer, green tea may be doubly beneficial.
Green Tea Dosing for Digestive Health
Green tea is generally considered safe in moderate amounts. In the average cup of green tea, expect a dose of 50 to 150 milligrams (mg) of polyphenols. The recommended dose is two to three cups of green tea per day (for a total of 100 to 320 mg of polyphenols, depending on the brand of tea) or 100 to 750 mg per day of a green tea extract. An important thing to remember is that green tea contains caffeine, which can cause or worsen insomnia, anxiety, irritability, and headaches. Caffeine in some people also can wreak havoc on digestive health, causing upset stomach, nausea, and diarrhea.
For people who are sensitive to caffeine, green tea extracts may be an option, and can be purchased in caffeine-free form. Studies on green tea extracts have demonstrated similar benefits to those associated with drinking it as a tea.
For example, researchers in the United Kingdom showed that green tea extracts affect the way the body breaks down food, concluding that the extracts increase fat oxidation and improve insulin sensitivity and glucose tolerance. Increased fat oxidation refers to what happens during exercise — it means that the body is doing a better job at converting stored fats into energy, which is a good thing if you’re trying to lose weight. The findings on insulin and glucose suggest that green tea extracts may help insulin work more efficiently in the body.
Although much of the research demonstrating green tea benefits is performed using extracts — it’s easier to control than having study participants drink cups of tea — it’s important to note that concentrated green tea extracts are metabolized differently than regular tea. There have been some reports of concentrated green tea extracts causing liver problems. These incidents are rare and have not been reported with other forms of green tea. But if you do take concentrated extracts, take them with food. People with existing liver problems should not take concentrated green tea extracts.
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