Green tea is a revolutionary drink in the world after it was promoted as an alternative to coffee for those trying to reduce caffeine intake, because it contains an amino acid known as “theanine” that slows down the absorption of caffeine and regulates blood sugar, in addition to supporting heart health, its richness in antioxidants that improves circulation It reduces the risk of blood clots and heart attacks, and helps reduce high blood pressure and bad cholesterol.

According to a study published by the American Medical Association, “those who drink at least one cup of green tea per day have a lower risk of death from heart disease,” as well as what some studies have proven to be effective in losing weight, enhancing athletic performance and endurance, to Besides its anti-inflammatory properties.

But this does not mean that there are some precautions that must be taken into account when drinking green tea in order to avoid many potential side effects in the event that its properties conflict with a person's health condition, or excessive drinking, or preparing it incorrectly, or taking it at inappropriate times.

Green tea supports heart health because it is rich in antioxidants that improve blood circulation, but it should not be consumed in excess (Shutterstock)

Green tea side effects

Chung S. says:

Yang, associate professor of chemical biology - in a study conducted by Rutgers University of America - said, "It is unlikely that people who consume less than 500 milligrams of green tea per day will develop toxic side effects, only high doses that may cause damage, if you drink a cup of coffee." Without feeling the following symptoms, you will not often experience the negative effects of this drink, and these are the most prominent damages of green tea

  • Stomach and digestive disorders

“People may experience stomach irritation after drinking green tea on an empty stomach,” says Dr. Yang, due to tannins or tannins, which increase stomach acids and lead to reflux and nausea, and steeping the tea in boiling water often exacerbates these effects.

Excessive consumption of green tea can also cause complaints of diarrhea, so it is recommended that people with irritable bowel syndrome, as well as patients with GERD and stomach ulcers, avoid it.

  • headache

The combination of caffeine and tannins (a headache trigger) in green tea can cause headaches for those sensitive to caffeine (a cup contains 22 to 40 milligrams), as well as those who suffer from daily headaches.

Green tea can cause headaches for those sensitive to caffeine (German)

  • vomiting

Experts advise to avoid drinking more than 4 cups of green tea per day, as excessive intake can lead to vomiting, so it is recommended to start taking one or two cups per day and increase it if you do not feel any side effects.

  • Anemia and iron deficiency

Containing green tea on tannins and some antioxidants that hinder the body’s absorption of iron can harm those suffering from anemia, according to two studies published in 2016 and 2017. This harmful effect can be avoided by drinking the drink before or an hour after a meal, to give the body time to absorb iron, or by adding lemon Vitamin C enhances iron absorption, although it is better to avoid green tea for those who suffer from anemia.

  • Bleeding disorders

A research published in 2020 stated that “in rare cases, if a person’s consumption exceeds 9 grams per day, green tea can lead to bleeding disorders,” as it prevents the oxidation of fatty acids, which may lead to blood thinning, and compounds in it reduce levels of “fibrinogen.” (Fibrinogen), a protein that helps blood clot, so if you have a blood clotting disorder it's best to avoid drinking green tea.

  • liver damage

High consumption of green tea (more than 4 to 5 cups a day) can harm the liver, as according to previous research, “the catechin component in green tea is the cause of hepatotoxicity in heavy drinkers.”

And researchers warn everyone who has had severe liver injury due to green tea extract to stop using it, (Green tea extract is a dietary supplement that may contain up to a thousand milligrams of antioxidants, which is different from green tea infusions that usually contain only 90 to 300 milligrams. of antioxidants), as “consuming more than 800 mg of antioxidants naturally found in green tea can lead to liver damage,” says the European Food Safety Authority (EFSA).

High consumption of green tea (more than 4 cups a day) can harm the liver (German)

  • Osteoporosis

Excessive consumption of green tea increases the risk of osteoporosis, as “compounds in it affect calcium absorption,” according to a study published in 2009, and the study confirmed “the interactive effects of green tea consumption on bone health,” noting that its conclusion requires further research. But experts advise reducing consumption of this drink to 2 or 3 cups, and taking calcium supplements for those who are prone to bone disease.

  • Pregnancy and breast-feeding risks

Experts link the contents of green tea from tannins, caffeine and antioxidants to an increased risk of pregnancy, but they allow quantities not to exceed 200 milligrams or two cups per day during pregnancy and lactation to avoid passing caffeine through breast milk.

  • sleep problems

Green tea contains an anti-sleep compound, caffeine, and although its percentage is lower compared to black tea, it may cause sleep problems for people sensitive to caffeine, in addition to other chemical compounds in green tea that prevent the secretion of sleep-inducing hormones, such as melatonin. While some people may benefit from a cup of green tea before bed, people with sensitivity to caffeine should drink it about 5 hours before bed.