Is matcha bad for you? Real risks and limits

Matcha is not bad for you, but it is a caffeinated drink, and that is where its real limits sit. A bowl made with 2 g of powder carries around 48 mg of caffeine, based on the 2.4 g per 100 g the USDA database gives for matcha in general, roughly half a cup of coffee. Trouble comes from excess, from individual sensitivity and from specific medical situations. This page sets out the actual risks and how to avoid them.

What matcha is, and what is in it

Matcha is a green tea made by milling the whole leaf of Camellia sinensis. Because you drink the unfiltered powder, compounds that would stay behind in a discarded teabag end up in the bowl. Specifically:

• Catechins, mainly EGCG. An analytical paper published in the Journal of Chromatography A in 2003 (Weiss and Anderton, PMID 14518774) measured, per gram of dry leaf, an EGCG concentration 137 times higher than the green tea China Green Tips.
• Chlorophyll and fibre from the leaf itself, behind the deep green colour and the dense texture of a whisked bowl.
• L-theanine and caffeine. A randomised placebo-controlled trial published in Nutrition Research in 2021 (Baba et al., PMID 33744591) gave 2 g of matcha daily for two weeks to 42 adults aged 25 to 34 and measured reaction times in the Stroop test after a stress task.
• Vitamin K, lutein and the amino acids of the leaf, which form part of the nutritional profile of the powder.

If you want to see what has been measured in clinical trials, in whom and for how long, we set it out with full references in our guide to matcha and the published research.

And if the chemistry interests you, we go through the catechins one by one in Matcha catechins: EGCG, ECG, CG and GCG explained.

So what are the real risks?

Matcha is a caffeinated drink, and caffeine is a stimulant of the central nervous system. In excess it can cause jitteriness, insomnia, a racing heart or anxiety, and those effects are the reason for every precaution below.

The amount of caffeine varies with grade and dose. According to the USDA database, 100 g of matcha contains 2.4 g of caffeine, about 24 mg per gram. A bowl made with 2 g therefore carries around 48 mg, roughly half a cup of coffee.

Matcha also contains L-theanine, an amino acid present in the tea leaf. On the combination of theanine and caffeine, a systematic review with meta-analysis of 50 randomised trials in healthy people published in Nutrition Reviews in 2025 (Payne et al., PMID 40314930) measured attention and mood tests during the first and second hour after intake, and the authors themselves stress that the confidence intervals leave the size of the effect in doubt. The caffeine in matcha is still caffeine, and the precautions are those of any drink that contains it.

Excess intake can produce caffeine overdose, which is a genuine medical event rather than a figure of speech. Symptoms include:

• Headache
• Nausea and vomiting
• Diarrhoea
• Irritability
• Tremor
• Palpitations
• Raised blood pressure
• Seizures
• Arrhythmia
• Heart attack

According to the Mayo Clinic, the maximum recommended caffeine dose for a healthy adult is 400 mg a day, which would be about 8 bowls of matcha. That figure varies with sensitivity, weight, age, health status and other factors, so the sensible line is 2 or 3 bowls a day, and not alongside other caffeine sources such as coffee, tea, chocolate, energy drinks or medicines that contain it. Reaching 8 bowls would take a determined afternoon and a great deal of whisking.

Some people should avoid or limit matcha altogether: pregnant or breastfeeding women, children, older adults, anyone with cardiac, kidney, liver, gastric or nervous system conditions, and anyone taking medication that interacts with caffeine.

One more warning sign of problem powder is the taste. If it tastes of fish, seaweed or metallic bitterness, that usually means low grade, oxidation or bad preparation. We break that down in what matcha tastes like, and why it sometimes tastes of fish.

How to drink matcha safely

• Choose good quality matcha, ideally organic, with no additives, colourings, sugars or pesticide residues.
• Prepare it with hot but not boiling water, around 80 °C, and whisk with a bamboo or electric whisk until a foam forms.
• If you add milk, cream, sugar or sweeteners, remember they change both the profile and the flavour. If you want milk, oat works best.
• Drink it in moderation, no more than 2 or 3 bowls a day, and avoid it in the evening or alongside other caffeine sources.
• If you have never had caffeine, have a medical condition, are pregnant, breastfeeding or taking medication, speak to your doctor first.

Conclusion

Matcha is a caffeinated drink, and that is both the point of it and the limit. One to three bowls of 2 g a day come to 48 to 144 mg of caffeine, well below the 400 mg that health authorities use as a daily reference for healthy adults. If you are pregnant, breastfeeding, taking medication or living with a medical condition, speak to your doctor before changing your caffeine intake. If you would rather start with a good ceremonial grade, ours is in the Matcha Zen collection.

References

1. Weiss DJ, Anderton CR., Determination of catechins in matcha green tea by micellar electrokinetic chromatography. Journal of Chromatography A, 2003. PMID 14518774. https://pubmed.ncbi.nlm.nih.gov/14518774/
2. Baba Y, Kaneko T, Takihara T., Matcha consumption maintains attentional function following a mild acute psychological stress without affecting a feeling of fatigue: A randomized placebo-controlled study in young adults. Nutrition Research, 2021. PMID 33744591. https://pubmed.ncbi.nlm.nih.gov/33744591/
3. Payne ER, Aceves-Martins M, Dubost J, Greyling A, de Roos B., Effects of Tea (Camellia sinensis) or its Bioactive Compounds l-Theanine or l-Theanine plus Caffeine on Cognition, Sleep, and Mood in Healthy Participants: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Nutrition Reviews, 2025. PMID 40314930. https://pubmed.ncbi.nlm.nih.gov/40314930/