Green tea and its health risks - what is really true?
Mr. Takayuki presents our Sencha No.1
Green tea is healthy. Most people now agree on this. But there are always voices warning of certain side effects: iron absorption is said to be inhibited or bones become brittle. This is unsettling. To inform you about the alleged dangers of Sencha and Matcha, we have taken a closer look at the three most widespread warnings and explain the harmful substances in green tea. It is important to us to describe the current state of knowledge as objectively as possible. You will therefore find many sources in link form. So if you are interested, you can read in detail and make your own picture of the studies.
Overview
Green tea inhibits iron absorption in the body
A typical Buddhist meal in a temple on Koyasan. Very tasty and completely vegan. The monks drink only green tea with it. Iron deficiency is not an issue here.
A delicious dinner and a hot green tea to go with it - better not, some warn. Green tea is said to inhibit the absorption of iron and could therefore cause an iron deficiency. What is the truth of this claim? Many studies have already been conducted on the subject and all agree on one thing: The absorption of iron from animal products and from tablets is not inhibited by green or black tea. Only in the absorption of iron from plant products there is disagreement. French researchers studied nearly 1000 healthy individuals and found no correlation between iron absorption and tea drinking. [1] In contrast, a Tunisian research group found that green tea inhibited the absorption of iron from couscous in rats.[2] To this end, it is important to know that the iron in plant foods has a lower bioavailability. This means vegetarians and vegans need a greater amount of plant-based iron to get to a healthy level. Here, therefore, the daily intake of iron tablets is worth considering.
In short, a healthy adult who eats a well-balanced diet without making any sacrifices can drink green tea without hesitation. This does not impair iron absorption. Only the absorption of iron from purely plant-based foods is controversial. However, as vegetarians or vegans supplement iron, nothing stands in the way of green tea enjoyment. If you suffer from iron deficiency anemia, are pregnant or unsure, talk to a doctor or nutritionist before consuming large amounts of green tea.
People with osteoporosis should not drink green tea
Many elderly people, such as this Chinese woman from Dali in southern China, benefit from the bone-protecting effect of green tea.
An Instagram user asked the question whether it is dangerous to drink green tea if you suffer from osteoporosis. This question surprised me. Until now, I only knew that green tea protects against osteoporosis.[3] In fact, however, from time to time you can find the warning that the high content of fluoride in green tea makes bones brittle. To say it right away: There is no such danger. A normal person would have to drink over 10 liters of green tea a day to trigger a negative effect on bones. In fact, just the opposite is true: green tea supports the healing of bones affected by osteoporosis. This effect is even stronger if you also do sports. So green tea is absolutely recommended for osteoporosis.[4]
But then where does this claim come from? It is true that an overdose of fluoride removes calcium from the bones and makes them brittle. However, this would require an adult to consume over 10 mg of fluoride daily. But there is just 1 mg of fluoride in a liter of green tea. Other foods contain even much less fluoride. Meeting or even exceeding the daily fluoride requirement of 4 mg through food is therefore not possible at all.[5]
In short, green tea protects against osteoporosis and helps bones heal. It does not contain enough fluoride to have a negative effect on bone structure. A complete diet plan that includes green tea is a good way to counteract osteoporosis. It is best to talk to a nutritionist about this.
Anxiety and nervousness get worse with green tea
Buddhist monks drink green tea to stay awake during meditation while calming the mind.
Before we dive into the scientific findings: Nervousness, anxiety and stress are highly subjective feelings. Even if studies show certain effects, you are the best judge of your own feelings. So if you are sensitive to green tea, it may be worth trying different varieties (Sencha, Matcha, Karigane,...) or looking for alternatives.
Green tea contains two components that have a significant effect on our well-being: Caffeine and Theanine. Theanine has a calming effect. It reduces both personal anxiety and situational stress, such as in an exam.[6] Caffeine, on the other hand, can aggravate anxiety and nervousness.[7] You may have heard of the typical "caffeine jitters" in connection with coffee. In contrast to coffee, however, green tea contains not only caffeine but also theanine in effective concentrations. Theanine acts like a buffer that balances the effect of caffeine. Therefore, tea does not usually have the stimulating effect of a cup of coffee. In fact, the effect of theanine seems to predominate in most people: studies have shown that green tea reduces anxiety and nervousness, and increases concentration and memory performance.[8]
In short, green tea can reduce anxiety and nervousness. However, individual reactions vary. To determine what works best for you, try different varieties. Caffeine and theanine content varies slightly by variety, harvest date, quality, and preparation. If you are sensitive to caffeine, we can recommend our Genmaicha, which contains almost no caffeine. This way you can slowly get used to green tea. Green tea is certainly not a miracle cure, but it could support you in difficult situations.
A word about green tea extracts
Even dogs are given extract of green tea. The usefulness of this is debatable. Image: RR_Medicinals (Pixabay)
Green tea extracts contain green tea and thus also the particularly health-promoting antioxidants in concentrated form. In high doses, however, these can be dangerous for health. Especially with fat burners that contain other extracts in addition to green tea, the effect is difficult to assess. The Canadian[9] and Norwegian[10] ministries of health, for example, have already expressly warned against highly concentrated preparations and their effect on the liver.
In short, the safest and also most relaxing option is drinking green tea. Especially shaded varieties, such as our Kabusecha green tea or Matcha te as naturally contain a high concentration of antioxidants. Green tea extracts, on the other hand, can have adverse effects. It is best to talk to your doctor before taking such supplements.
Pesticides in green tea
In order to benefit from the many positive effects of green tea, it is very important not to ingest pollutants that can get into the tea during cultivation and harvesting. But how can you be sure that it is really green tea without pesticides? Stiftung Warentest, for example, found pesticides in all 25 green teas tested (organic and conventional cultivation) in a test [11]. Therefore, it is quite clear: Whether it is conventional green tea or organic tea - pesticide-free must be proven by testing. This is also the reason why we have each of our teas once again externally tested for pesticides. We provide you with the corresponding test report in our green tea store on the product page of each of our Senchas & Matchas and show you where exactly the tea comes from. Only in this way can you be sure that only what is in it, should be in it: 100% pesticide-free & unblended green tea.
CONCLUSION: Listen to your body and common sense
Green tea has many positive effects on the body. The effect on metabolism & fat burning we have summarized for you in the article Lose weight with green tea. The negative effects on iron absorption and osteoporosis are largely scientifically refuted. Some study results also speak for the consumption in case of anxiety or nervousness. Nevertheless, if you notice any undesirable effects, are uncertain or suffer from chronic diseases, consult your doctor or nutritionist beforehand. Also for women in pregnancy: Please talk to your doctor about the allowed amount of caffeine. Neither this blog entry, nor other well-meaning advice from the Internet or acquaintances replace a professional expert opinion.
[1] Consumption of black, green and herbal tea and iron status in French adults.
[2] Effect of Tea on Iron Absorption from the Typical Tunisian Meal 'Couscous' Fed to Healthy Rats.
[3] Association between tea consumption and osteoporosis
[4] Effect of green tea and Tai Chi on bone health in postmenopausal osteopenic women: a 6-month randomized placebo-controlled trial.
[5] Fluoride - protection for the teeth
[6] Anti-stress effect of theanine on students during pharmacy practice: Positive correlation among salivary α-amylase activity, trait anxiety and subjective stress.
[7] Panic disorder and social anxiety disorder subtypes in a caffeine challenge test.
[8] Green tea effects on cognition, mood and human brain function: A systematic review.
[9] Summary Safety Review - Green tea extract-containing natural health products - Assessing the potential risk of liver injury (hepatotoxicity).
[10] Safety assessment on levels of (-)-Epigallocatechin-3-gallate (EGCG) in green tea extracts usedin food supplements.
[11] https://www.test.de/Tee-Einige-gruene-Tees-fuer-die-Gesundheit-auf-Dauer-riskant-4914954-0/