Green tea, which includes matcha tea, is recognised for its many benefits thanks to its high content of antioxidants. However, could these virtues come with certain risks? Recent studies raise the question: is green tea dangerous for the liver or beneficial? And what about its effects on the stomach? Let's see how to get the most out of it while avoiding health risks.
Summary of the effects of green tea on the liver and stomach
Here's what you need to know to find a balanced approach to green tea consumption:
- Benefits for the liver: Green tea, rich in antioxidants such as EGCG, can reduce the risk of liver disease according to scientific studies. However, excessive consumption can be toxic to the liver.
- Digestive effects: Matcha can soothe digestive inflammation and balance acidity thanks to its polyphenols. However, excessive consumption can cause problems such as bloating, diarrhea, or stomach ache due to the tannins and caffeine.
- Recommended consumption: Limit yourself to 2 cups per day to enjoy the benefits without risk.
- Drug interactions: Green tea may interfere with certain medications such as warfarin or atorvastatin. Consult a doctor if you are taking regular medication.
Tip: Prepare your matcha with water at 70°C, avoid consuming it on an empty stomach, and choose an organic product, such as Yabukita organic matcha, to limit the risks.
Effects of green tea on the liver
The liver is one of the organs most sensitive to active substances. Let's examine the potential effects of green tea, both beneficial and risky.
Positive effects on liver health
Several scientific studies indicate that green tea, and more specifically matcha, may have a beneficial protective effect on the liver. Its antioxidant properties are mainly due to its high catechin content, particularly epigallocatechin-3-gallate (EGCG).
Among the notable results:
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A 2015 meta-analysis of 15 studies showed that regular consumption of green tea is associated with a reduced risk of liver disease.
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A study on mice fed a high-fat diet revealed that matcha limits fat accumulation in the liver and improves its function.
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ARN analyses have shown stimulation of cytochrome P450 enzymes, indicating improved hepatic metabolism.
"The catechins in green tea increase the genetic expression of these enzymes, which may be beneficial for people with initially low levels." - H.-H. Sherry Chow, Ph.D., Associate Research Professor at the University of Arizona
However, these benefits depend heavily on the quantity consumed. In excess, green tea can also have significant adverse effects, as we will view below.
Risks associated with excessive consumption
While green tea can be beneficial in moderate doses, excessive consumption—particularly in the form of concentrated extracts—can cause toxic effects on the liver.
Here are the key points to remember:
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Green tea extracts (in capsules or supplements) present a higher risk of toxicity than brewed tea.
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High doses of EGCG, between 700 and 2,000 mg per day, have been associated with liver damage in several studies.
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The recommended safety threshold for adults is set at 338 mg of EGCG per day.
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A typical cup of green tea usually contains 90 to 300 mg of EGCG, which is still reasonable.
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Matcha, on the other hand, is more concentrated and also contains more caffeine (19–44 mg/g, compared to 11–25 mg/g for classic green tea), which can amplify side effects.
This raises a legitimate question addressed in another item: is it safe to drink matcha tea every day?
Interactions with medications
In addition to the risks of overconsumption, green tea can interfere with certain medications:
| Medicine | Level of interaction |
|---|---|
| Dicumarol | Major |
| Atorvastatin | Moderate |
| Warfarine | Moderate |
| Digoxin | Moderate |
| Tacrolimus | Minor |
"The key message is to consult your healthcare professional before taking any dietary supplement. They know your pre-existing conditions and can assess potential interactions with your current medications." - Kristi Muldoon-Jacobs, Ph.D., Director of Regulatory Affairs at USP
For people with liver disease, it is crucial to monitor symptoms such as jaundice, dark urine, or abdominal pain. As a general rule, moderate consumption of 1 to 2 cups per day is recommended for healthy individuals.
Green tea: dangerous for the stomach?
Let's dive into the impact of matcha on digestive health and therefore on the stomach by exploring its positive effects and possible drawbacks.
Benefits for the digestive system
Matcha can be a valuable ally for digestion, provided it is taken in the right doses. Its active ingredients act on different levels:
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Its catechins help reduce digestive inflammation, particularly in cases of intestinal irritation or imbalance.
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Thanks to its pH close to 7.5, it can neutralize excessive acidity in the stomach.
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Its polyphenols have a prebiotic effect, promoting a healthier gut microbiome.
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It is also rich in L-theanine, an amino acid recognised for its relaxation effects, which are useful when stress aggravates digestive problems.
In equivalent quantities, matcha offers much higher nutritional benefits than classic green tea:
| Component | Matcha (1 teaspoon) | Classic green tea (1 pouch) |
|---|---|---|
| Catechins | 105 mg | 63 mg |
| L-theanine | 45 mg | 9 mg |
| Vitamin C | 5 mg | 2 mg |
"Matcha offers a potential natural approach to supporting digestive health, particularly in people suffering from acid reflux and GERD." - Bonsai Cha
Warning: despite these benefits, excessive consumption can cause side effects.
Stomach discomfort issues
For some people, green tea can cause digestive problems. Tannins, for example, increase stomach acidity, leading to pain, nausea, or even constipation. Caffeine, at 35 mg per cup, can also aggravate these symptoms.
Research shows that excessive consumption of matcha is linked to various digestive discomforts:
| Digestive effect | Frequency (%) |
|---|---|
| Diarrhea | 20 |
| Bloating | 15 |
| Stomach ache | 10 |
"The tannins in green tea increase stomach acidity, which can cause stomach upset, nausea, or constipation." - Dr. Richa Garg, Ayurveda
To limit these risks, here are a few simple tips:
- Avoid drinking matcha on an empty stomach.
- Prepare it with water between 70 and 82°C.
- Opt for ceremonial-grade matcha.
- Consume a maximum of 2 to 3 cups per day.
- Stay hydrated throughout the day.
If you suffer from irritable bowel syndrome (IBS) or gastric ulcers, consult a healthcare professional before adding matcha to your diet.
How to drink green tea for good health
To enjoy the benefits of green tea without suffering any adverse effects, there are a few best practices for consumption.
Recommended quantity per day
To avoid excess, moderate the quantity of tea you drink each day. Limit your green tea consumption to 2 cups per day, or approximately 16.5 ounces. Although green tea contains less caffeine than coffee, it is important to adjust your consumption based on your personal tolerance.
Proper preparation
To fully enjoy the health benefits of matcha, it is essential to prepare it properly. Val de Kumiko Matcha, an expert in matcha green tea, recommends the next traditional method of preparing matcha:
- Sift 2 g of matcha into a tea bowl.
- Add 60 ml of water heated to 70°C.
- Whisk with a Chasen (bamboo whisk) in a "W" motion until you obtain a fine froth.
- Then dilute with 120 ml of water to obtain a balanced drink.
Best times to consume
The time of day you drink your matcha can influence its effects. Here's when to drink matcha green tea:
- Take it 30 to 60 minutes before or after a meal to maximize its appetite-suppressing effect and aid digestion. Avoid taking it with meals, as this may interfere with iron absorption.
- If you are sensitive to caffeine, avoid drinking it in the late afternoon or evening.
- For greater comfort, accompany your matcha with a light snack to avoid any stomach discomfort.
Conclusion: Green tea, beneficial or dangerous for the liver and stomach?
Green tea, and matcha tea in particular, can be a valuable ally for liver and digestive health, thanks to its high content of antioxidants, such as EGCG. However, these health benefits depend directly on the dosage and quality of the product consumed.
Moderate consumption—about 2 cups per day—generally prevents adverse effects such as digestive problems or liver damage. However, excessive consumption or the use of concentrated supplements can make green tea dangerous for the liver and sometimes irritating to the stomach in sensitive individuals.
Key recommendations for safe consumption:
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Choose high-quality organic matcha to avoid contaminants.
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Stick to the daily dose of 2 to 4 g to stay below the EGCG toxicity threshold.
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Avoid consuming it on an empty stomach or too late in the day, especially if you are sensitive to caffeine.
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Prepare it with water at 70°C to preserve its benefits without upsetting the digestive system.
In summary, green tea is not inherently dangerous for the liver or stomach, but moderate consumption is essential. If in doubt or if you have a specific medical condition (reflux, ulcers, medication), it is best to seek the advice of a healthcare professional.
FAQ on green tea being harmful to the liver or stomach
What are the signs of liver damage caused by green tea?
Liver damage caused by excessive consumption of green tea can manifest itself in several symptoms to watch out for, including jaundice (coloured skin and eyes), dark urine, pain or discomfort in the upper right abdomen, unexplained fatigue, and nausea or vomiting. If you experience these symptoms after consuming large amounts of green tea or green tea supplements, it is important to consult a healthcare professional promptly.
Can green tea cause acid reflux?
Although green tea is often beneficial for digestion, in some sensitive individuals, its caffeine and tannins can promote gastroesophageal reflux disease (GERD) by relaxing the esophageal sphincter. It is therefore recommended to consume it in moderation and avoid drinking it just before bedtime.
Can green tea cause liver damage in healthy people?
In healthy individuals, moderate consumption of green tea is generally safe for the liver. The risk of liver damage mainly occurs in cases of excessive consumption, particularly through supplements focused on catechins. It is therefore recommended to follow the recommended doses to avoid any problems.
Can green tea be consumed during pregnancy without risk to the liver or stomach?
Pregnant women should consume green tea in moderation due to its caffeine content. It is advisable not to exceed 1 to 2 cups per day and to consult your doctor to avoid any potential risks to liver or stomach health.
