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11 Green Tea Side Effects You Never Knew About

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Going green is the key, they said. And that’s what we thought too. And we started drinking green tea. All well, until some person in some laboratory, does some research and comes up with something not-so-appealing. That green tea has side effects.And we better understand that too. Because yes, green tea has side effects.

Green Tea – A Brief

In a way, this could be the healthiest drink on the planet. And all those claims about green tea that have been grabbing your eyes and ears all these years, well, they are true. At least, most of them.

The tea has been found to enhance brain function and prevent age-related memory issues. It also helps prevent cancer and is an effective ingredient that goes into most weight loss diets. Antioxidants, if you ask me. That is what green tea is made of. Additional benefits include enhanced dental health and improved immunity. Numerous benefits. But there is another point you might have goofed. It happened to me too. The side effects.

How Can Green Tea Be Bad For You?

Green tea is, you know, tea. And like any tea, it contains caffeine. That’s something we must accept first. Excessive caffeine consumption has been linked to nervousness, shakiness, and anxiety. And people who are intolerant to caffeine suffer more – they experience the symptoms even with little amounts of caffeine.

Also, green tea can damage the body’s ability to absorb iron. Now, that’s a problem. A deficiency of iron can give you a whole set of serious problems. Green tea also interacts with certain medications, and the consequences are painfully unpleasant.

One research conducted sometime in the previous decade suggested that the link between green tea and cancer prevention was weak and contradictory. So is the case with dementia and Alzheimer’s. Another research found a pretty weak link between green tea intake and reduced cholesterol levels. Numerous contradictions.

Drinking green tea in excess can end in caffeine overload, which consequently causes insomnia, tremors, restlessness, upset stomach, etc. Of course, this is more noticeable in people who tend to consume it in excess all of a sudden. In other words, if you are sensitive to caffeine, you are more receptive to the side effects. As per researches, up to 400 mg of caffeine in a day is safe for most adults. Which is roughly the amount in 4 cups of brewed coffee or 10 to 12 cups of green tea.

The Side Effects Of Green Tea

1. Stomach Problems

Caffeine could be the most common culprit. Though it has a lower amount of caffeine than other types of tea, it still can cause problems. This is because caffeine increases the amount of acid involved in the digestive process. This can cause pain or nausea.

Also, though green tea has been touted to prevent cancer, especially gastric cancer, studies say that there is insufficient information in this regard.

As per a report published by the University of Rochester Medical Center, if you experience stomach pain after drinking green tea, visit your doctor right away.

2. Insomnia

Another possible bad effect of green tea is a problem with sleeping. This can be averted by limiting green tea consumption, as the fatal dose of the caffeine in green tea is estimated to be 10 – 14 grams in a day.

Taking green tea too late in the day can also cause this effect. One very obvious reason for this is the caffeine, which stimulates the nervous system and can interfere with one’s sleep. More importantly, pregnant and lactating women must limit their green tea intake as it may pass into breast milk and cause insomnia in nursing infants.

A report by the Southern Illinois University states that green tea can cause numerous other sleep disorders as well if taken in excess.

3. Heartburn

Green tea is acidic, and hence can irritate the esophageal lining, causing acid reflux or heartburn. The condition could get worse if an individual is already suffering from heartburn (or acid reflux). Though normal brewed green tea could not be so potent, the bottled green tea that you so often find in the markets could be the real threat. This is because most of the green teas that come in bottles are fortified with an acidic preservative like ascorbic acid. This preservative can loosen the lower esophageal sphincter, which otherwise keeps the stomach acid from rising up the esophagus.

Certain bottled green teas come with a citrus flavoring, making them all the more acidic.
And in case you prefer to go for green tea capsules, discuss with your doctor once. Because the green tea extract in the capsules might also trigger heartburn symptoms. Also, only buy high-quality tablets at a proper health food store.

According to a Japanese study, green tea consumption has been linked to GERD, or gastroesophageal reflux disease. The caffeine in green tea was also found to increase stomach acid, which can lead to gastritis.

4. Iron Deficiency And Anemia

As per a Taiwanese study, consuming too much of green tea could lead to iron deficiency anemia. More importantly, taking green tea after an iron-rich meal can make the main compounds in the tea bind to the iron. If this happens, the green tea will lose its potential as an antioxidant.

EGCG is the main compound in green tea. This compound is known to inhibit an enzyme called myeloperoxidase, which might cause inflammation. But when the tea is consumed along with iron-rich foods, EGCG loses its ability to inhibit the inflammatory action of myeloperoxidase, thereby leading to inflammation. In other words, it’s not just what you eat, but also what you eat it with, which determines the benefits.

Green tea contains tannins that block the absorption of iron from food and food supplements. Certain sources say that adding lemon to green tea or drinking it in between meals can counter this issue. Further research adds that consuming tea can decrease the absorption of iron from plant-based sources (as much as by 64%). For mitigating the effect, one can drink tea at least one hour before or after meals; and also include more foods rich in vitamin C (as vitamin C aids in iron absorption).

Another Taiwanese study has also linked excessive tea consumption (green tea, in particular) to decreased iron absorption and resultant anemia. And according to a report by the Penn State University, the polyphenol antioxidants in green tea can inhibit iron absorption. This happens when the polyphenols bind to the iron in the intestinal cells and prevent it from entering the bloodstream. This polyphenol-iron complex is eventually excreted from the body.

5. Headaches

Again, because of the caffeine, green tea might cause mild to severe headaches. And headaches can also be caused by iron deficiency, which, as we have seen already, could occur through an excessive intake of green tea.

Apart from headaches, green tea can also cause dizziness. And as per studies, the maximum tolerated dose of green tea in humans is 9.9 grams per day – which is roughly equivalent to 24 cups of the beverage in a day. One important point to note is that though the green tea extract is listed in over 100 over-the-counter herbal supplements and preparations, its use as a treatment for any ailment is not strictly regulated by the FDA. Also, the safety of the long-term use of green tea extracts is not clearly defined.
Green tea can make one feel jittery and shaky, which may not be the case with decaffeinated green tea products.

6. Irregular Heartbeat

It’s caffeine, again. Caffeine is known to stimulate the heart as well. It causes your heart rate to speed up, causing irregularly fast heartbeat – a condition called tachycardia. This condition can make you feel as if your heart is pounding in your chest. You are more aware of your heartbeat than usual. Also called palpitations, this condition could even result in chest pain or angina (any other intense localized pain). A change in your normal heart rate could pose a serious threat.

According to another report by the Health University of Utah, intaking of a green tea capsule must be reconsidered in case you are suffering from heart disease or an irregular heartbeat.

7. Nausea and Vomiting

As per one Indian study, green tea polyphenols can, in fact, cause oxidative stress. And excessive intake of caffeine, including that from green tea, can trigger nausea and vomiting.

Moderate amounts of caffeine are noted to be 300 to 400 mg per day. If the amount exceeds, it can result in certain side effects, including vomiting.

8. Bleeding Disorders

Caffeine in green tea can increase the risk of bleeding. Which is why you must stay away from it if you have any bleeding disorder.

According to the University of Maryland Medical Center, green tea, when mixed with aspirin, might prevent the blood from clotting. Using the two at a time can increase your risk of bleeding.

9. Skin Allergies

The commonest allergies associated with green tea consumption are eczema and hives. An individual can also experience a tingling sensation on the face, lips, tongue, or in the throat.

Although rare, one severe allergic reaction green tea can cause is an anaphylactic shock. This is when the throat swells, blood pressure levels suddenly drop, hives break out, the abdomen might start to ache, and the individual might experience dizziness and anxiety.

10. Frequent Urination

The caffeine in green tea also acts as a natural diuretic. As per reports, keeping green tea intake within 5 cups per day (or 200 to 300 mg of caffeine per day) can be one solution.

Green tea is also one of those beverages that can aggravate the bladder. This is especially true if the individual is suffering from a urinary tract infection. In such an eventuality, they must avoid green tea (or any form of caffeine) and drink plenty of water instead.

The caffeine in green tea can also cause bladder spasms leading to bladder control issues. Caffeine can even constrict the smooth muscles of the bladder, making urination difficult. One alternative could be intake of decaffeinated green tea. But hey, consult your doctor first. In fact, frequent urination is one of the symptoms of caffeine sensitivity one must watch out for.

In certain sensitive women, tea might even cause bladder irritation and make them leak urine. In fact, avoiding tea or coffee or any caffeinated beverage (including green tea) is one way to help treat urinary tract infection.

11. Fertility

One study states that consuming green tea too often can lower fertility. In the study, embryos and larvae subjected to smaller doses of green tea were slower to develop. They also showed a decline in their ability to produce offspring.

In another study, the test group treated with green tea leaf extract showed a decrease in the serum testosterone levels.

Green tea was also found to impair development and reproduction in fruit flies. And similar results are potentially possible in humans as well.

How Much Of Green Tea Is Considered Safe?

An ideal dose of green tea is 3 to 5 cups per day, which could be equal to 1,200 ml (or 250 mg of catechins). Never take green tea on an empty stomach as it might cause liver toxicity.

If you are suffering from anogenital warts, the dosage would be topical application of the tea thrice a day for a minimum of 6 weeks. If you are suffering from heart disease, the dosage would be 400 to 716 mg of catechins per day. For diabetics, the dosage of EGCG would be 84 to 386 mg per day. And for obese individuals, it is 125 to 625 mg of catechins per day.

But like always, check with your doctor – as (s)he would know your condition best.


Go green. But not greener.

But before that, do let us know how this post on what are the side effects of drinking green tea has helped you. We are looking forward to hearing from you about other dangers of green tea. It helps us serve you better, which is all we care about.

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