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The green tea is one of the oldest herbal teas known to man. It quickly gained prominence in the West due to its supposed health benefits , with weight loss being one of the most popular. Some of these health benefits are supported by studies, while others still need to be investigated. In any case, we think we also need to be aware of its side effects. Green tea is safer for adults when consumed in moderation. Green tea extract is also considered generally safe for most people when taken orally or applied topically to the skin for a short period of time. However, drinking too much green tea (more than 5 cups a day) is considered unsafe. When consumed in excess, the side effects of green tea include stomach problems, heartburn, diarrhea, headache, palpitations and arrhythmias, anemia, tremor and muscle contractions, diabetes, glaucoma, high blood pressure and osteoporosis.

People who have a low natural tolerance to caffeine will suffer these symptoms even when they ingest small amounts. Some may already be suffering from problems that could be aggravated by the consumption of green tea. These people should limit the consumption of green tea to a maximum of 2 cups a day. The time to drink green tea is also crucial.

Green Tea Side Effects:

Like all teas, green tea contains caffeine; Excessive caffeine consumption can cause or aggravate a variety of problems, including the following:

1. Stomach Problems:

The tannins present in green tea increase heartburn that can cause stomach pain, nausea or constipation. For this reason, green tea is not consumed on an empty stomach in Japan and China. A study on dietary supplementation with green tea extracts found that green tea supplement on an empty stomach can affect the liver. It is better to drink green tea after a meal or between meals.

“People with peptic ulcers or acid reflux should not consume excess green tea”.

A 1984 study concluded that tea is a potent stimulator of gastric acid, which can be reduced by adding milk and sugar. Sometimes, improper infusion of green tea can also have adverse effects. Green tea is best prepared with water between 160 ° and 280 ° F. Excessively hot water can cause heartburn or upset stomach.

2. Iron Deficiency and Anemia:

Green tea reduces the absorption of iron from food. Its polyphenols bind iron and make it less available to your body. It was previously believed that green tea prevented the absorption of nonheme iron (iron of animal origin) by 25%. But recent findings suggest that it also hinders the absorption of heme iron or plants. However, vitamin C increases the absorption of nonheme iron, so you can squeeze lemon in your tea or eat other foods rich in vitamin C such as peas, broccoli and tomatoes with your meal. If you have an iron deficiency such as anemia, the National Cancer Institute recommends drinking tea between meals.

3. Mild to Severe Headaches:

Although green tea is considered a safe drink for migraine patients, it may still be off the diet chart for people with chronic daily headaches. Population-based research studies have shown that caffeine is a risk factor for the chronic onset of daily headache, and although green tea contains much less caffeine than coffee or other types of tea, it is better than these People avoid it.

4. Sleep Problems, Nervousness and Anxiety:

No matter how little caffeine green tea contains, it is not a sleeping drink. Caffeine by itself can block the chemicals that induce sleep in the brain and increase adrenaline production. Caffeine exerts obvious effects on anxiety and sleep, which vary according to your sensitivity to it. Green tea also contains the amino acid L-Theanine, which has the ability to calm down, but it will also make you alert and concentrate better, which will not allow you to sleep well at night.

5. Irregular or Fast Heartbeat:

The caffeine in green tea could cause an irregular heartbeat. It also stimulates the heart muscles to contract when they are at rest.

6. Vomiting:

Because caffeine affects the movement of food through the feeding tube, alternating contraction and relaxation of the muscles in the feeding tube can cause nausea.

7. Diarrhea:

Caffeine has a laxative effect. It contributes to peristalsis (the movement of food through the digestive system). It stimulates the muscles of the colon to contract and then relax, resulting in a greater need to defecate.

8. Tremors and Muscle Contractions:

By regulating the calcium ion channels inside the cells, caffeine forces the contractions of skeletal muscle.

9. Heartburn:

Caffeine increases the release of acid in your stomach. This causes discomfort similar to heartburn.

10. Dizziness:

Caffeine can decrease blood flow to the brain, leading to dizziness and dizziness.

11. Ringing in The Ears:

Caffeine can aggravate tinnitus or ringing in the ears.

12. Seizures:

Caffeine stimulates the central nervous system. Activates neurons when consumed in excess, causing seizures.

13. Hemorrhagic Disorders:

The caffeine in green tea may increase the risk of bleeding.

14. Diabetes:

The caffeine in green tea could interfere with blood sugar control. If you drink green tea and have diabetes, carefully control your blood sugar level.

15. Glaucoma:

Drinking green tea increases the pressure inside the eye. The increase occurs within 30 minutes and lasts at least 90 minutes.

16. High Blood Pressure:

The caffeine in green tea may increase blood pressure in people with high blood pressure. However, this does not seem to occur in people who regularly drink green tea or other products that contain caffeine.

17. Liver Disease:

Green tea extract supplements have been linked to several cases of liver damage. Green tea extracts may make liver disease worse because blood caffeine can accumulate and last longer.

18. Osteoporosis:

Drinking green tea can increase the amount of calcium that is eliminated in the urine, which can lead to deterioration of bone health and osteoporosis, especially in those who may be predisposed to the same due to other factors. Caffeine should be limited to less than 300 mg per day (approximately 2-3 cups of green tea). It is possible to compensate for some calcium losses caused by caffeine by ingesting calcium supplements.

19. Health Risks of Pregnancy and Infant:

Green tea contains caffeine, catechins and tannic acids. All three substances have been related to the risks of pregnancy. If you are pregnant or breastfeeding, green tea in small amounts – about 2 cups per day – is safe. This amount of green tea provides about 200 mg of caffeine. However, drinking more than 2 cups of green tea a day has been linked to an increased risk of miscarriage and other negative effects. Caffeine passes into breast milk and can affect a nursing baby. In addition, drinking a large amount can cause congenital neural tube defects in babies.

20. Nutrient Absorption Problems in Children:

The tannins in green tea can block the absorption of nutrients such as proteins and fats in children. It can also lead to overstimulation due to the caffeine present in green tea.

Can People Who Take Medicine Drink Green Tea?

 Green tea should not be taken with these narcotic drugs and medications as it is known to cause negative reactions:

Highly Interactive:

Stimulant drugs such as amphetamines, nicotine, cocaine and ephedrine.

Moderately Interactive:

Adenosine, quinolone antibiotics, contraceptive pills, Cimetidine (Tagamet), Clozapine (Clozaril), Dipyridamole (Persantine), Disulfiram (Antabuse), estrogen pills, Fluvoxamine (Luvox), Lithium, Depression medications (MAOX), Hepatotoxic drugs , medicines that slow blood clotting (Anticoagulants / Antiplatelets), Pentobarbital (Nembutal), Phenylpropanolamine, Riluzole (Rilutek), Theophylline, Verapamil and Warfarin.

Slightly Interactive:

Alcohol, Fluconazole, Anti-diabetes, Mexiletin (Mexitil) and Terbinafine.

How to Consume Green Tea?

The United Kingdom Tea Council recommends not drinking more than 6 cups of tea a day. To obtain the best health benefits, 3 to 4 cups are recommended. However, doses of green tea vary significantly, but usually range from 1-5 cups daily is considered safe. The commonly used dose of green tea is based on the amount typically consumed in Asian countries, which is about 3 cups per day, providing 240-320 mg of the active ingredients, polyphenols. To make tea, people typically use 1 teaspoon of tea leaves in 250 ml of boiling water. Drink green tea when it is fresh but slightly cold. Scalding tea can damage your digestive system. In addition, recent studies suggest that too much hot tea can promote throat cancer. The compounds in tea such as catechins, theanine and vitamins C and B decrease over time through oxidation, so the health benefits are stronger with fresh tea. If you are preparing the same tea leaves, do them in moderation. With each successive infusion, the cancerous substances in the leaves themselves (often pesticides) are extracted and can even be toxic. Old tea can also harbor bacteria, especially because its antibacterial properties decrease over time.


You don’t have to stop drinking your favorite cup of green tea, but if you have any of the medical conditions mentioned above or are taking prescription medications, be careful and ask your doctor about how many cups you can drink per day. Moderation is the key to enjoying all the benefits of green tea.



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