Green Tea: Health Benefits, Negative Side Effects & Risks

Green Tea, a product made from the leaves and leaf buds of plant Camellia sinensis, is an unfermented tea (beverage or an extract) produced by steaming fresh leaves at high temperatures. Green tea has become popular world-wide because of its medicinal value. However, along with various health benefits, green tea is also associated with some negative side effects and risks. We will be discussing all that in this article.

Picture Showing a Cup of Fresh Green Tea Along with Leaves

Health Benefits

Green tea contains large amounts of many vital natural antioxidants, especially the micronutrients called Catechins and its derivatives called Polyphenols, which promote good health. Green tea contains potent antioxidants that counteract the effects of oxidant (free) radicals; the byproducts of the body that can damage cells & tissues. The catechins provide anti-viral and anti-bacterial properties that protect our respiratory, gastro-intestinal & urinary tracts. High doses of green tea are shown to reduce the degradation of tissues and improve the blood flow, thereby maintaining a healthy circulatory system.

Green tea helps to improve mental alertness and thinking, promotes healthy skin and may help stave off colds and flues. However, some manufacturers and suppliers sell green tea and its supplements with wide variety of health claims that are not complete facts. They say that green tea lowers Cholesterol levels, the risks of cardio vascular diseases and even prevents & treats Cancer. You can read a detailed analysis on all those claims on facts analysis website

Picture Showing a Green Tea Plantation Field

Side Effects

Apart from its health benefits, green tea can cause side effects in some people, especially in large doses. In some people green tea consumption can cause stomach upset and constipation.

Other possible side effects of green tea include irritability, mild to serious headache, nervousness, dizziness, ringing in the ears, sleep problems, vomiting, diarrhea, irregular heartbeat, tremor, heartburn, convulsions and confusion.

The Caffeine in the green tea can increase the amount of calcium flushed out in the urine and cause Osteoporosis (weak bones). So caffeine intake should be limited to less than 300 mg per day (around 2-3 cups of green tea).

In pregnant people, daily consumption of more than 2 cups of green tea has been linked to an increased risk of miscarriage and other negative effects. Moreover, caffeine passes into breast milk and can affect a nursing infant, so do not take excessive amounts of green tea if you are pregnant or breast-feeding.

In people with Diabetes, the caffeine content in green tea might affect blood sugar control, so they have to monitor their blood sugar carefully.

Health Risks

People with low tolerance for caffeine will suffer many side effects of green tea discussed above, even when taken in small amounts.

In rare cases, green tea extracts & supplements containing concentrated amounts of polyphenols have been reported to cause liver problems, they might make liver disease worse.

Drinking green tea may cause “tired blood,” i.e. make iron-deficiency anemia worse, because it seems to reduce the bioavailability and absorption of nonheme iron. Nonheme iron is the primary type of iron found in eggs, dairy and some plant foods like beans. To reduce this effect, you can squeeze lemon into your green tea or take other vitamin-C rich foods like broccoli along with your meal.

If you have a bleeding disorder, do not drink green tea, because the Caffeine content might increase the risk of bleeding.

Green tea interacts with many medications like antibiotics, blood thinners, stimulants, certain asthma and hormone medications, or any drug posing a risk to liver health. So in such cases, it is necessary to check with your doctor before taking green tea.


Green tea: MedlinePlus Supplements

Prashanth Damarla

I write.

2 thoughts on “Green Tea: Health Benefits, Negative Side Effects & Risks

  • February 21, 2016 at 2:19 PM

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    • February 23, 2016 at 12:48 PM

      Thank you Amat! We are glad to hear that. 🙂

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