Matcha has gained significant popularity as a health beverage, praised for its high antioxidant content and calming, focused energy. Unlike traditional green tea, which is brewed and discarded, matcha powder involves consuming the entire tea leaf, resulting in a more concentrated dose of its compounds. While this offers amplified benefits, it also increases the potency of potential negative effects that can arise from overconsumption or low-quality products.
Caffeine and associated side effects
Matcha naturally contains caffeine, and while the L-theanine amino acid provides a sense of calm alertness, excessive intake can lead to problems, especially for those who are caffeine-sensitive. A typical 1-gram serving of high-quality matcha can contain around 35-50mg of caffeine, though this varies significantly by grade and preparation. The average adult should not exceed 400mg of caffeine per day from all sources.
Common caffeine-related side effects include:
- Anxiety and jitteriness: High doses can overstimulate the nervous system.
- Insomnia: Consuming matcha too late in the day can interfere with sleep patterns.
- Heart palpitations: Excessive caffeine can cause a racing or irregular heartbeat.
- Headaches: Sometimes a symptom of overconsumption, especially when accompanied by dehydration.
Contaminants in matcha powder
Since matcha involves consuming the entire ground tea leaf, there is a risk of ingesting contaminants absorbed by the plant from the soil.
Heavy metals and pesticides
Tea plants can absorb lead, arsenic, and other heavy metals from polluted soil. While reputable brands, particularly those from Japan, conduct rigorous testing to ensure levels are safe, cheaper products from unregulated sources may pose a risk. Pesticide contamination is also a concern, with some studies highlighting the presence of hazardous pesticides in green tea samples. Choosing high-quality, organic, and third-party-tested matcha is the best way to mitigate this risk.
Potential liver and kidney impact
Some research suggests that extremely high doses of catechins, the powerful antioxidants in green tea, may negatively impact liver and kidney function, though this is most often linked to concentrated green tea supplements rather than the tea powder itself. Moderate consumption of matcha tea poses little to no risk for most people with healthy liver function.
Digestive problems
For some, drinking too much matcha can cause gastrointestinal discomfort.
Stomach upset and acid reflux
The tannins and caffeine in matcha can irritate the stomach lining, especially when consumed on an empty stomach. This can lead to nausea, stomach pain, and heartburn in sensitive individuals. Drinking matcha with or after a meal can help reduce this risk.
Constipation or diarrhea
Matcha's high fiber content can sometimes trigger a laxative effect in those unaccustomed to it, leading to diarrhea. In other cases, excess consumption has been linked to constipation.
Interference with nutrient absorption
The catechins and tannins present in matcha can interfere with the absorption of certain nutrients, most notably non-heme iron from plant-based foods. Individuals with anemia or iron deficiency should consume matcha at least two hours before or after meals to avoid affecting iron levels. Similar effects have been noted regarding folate absorption.
Considerations for specific populations
Pregnancy and breastfeeding
Medical guidance suggests that pregnant and breastfeeding women limit their caffeine intake to 200mg or less per day. While moderate matcha consumption (1-2 cups) can fit within this limit, concerns about potential contaminants and catechins mean a consultation with a healthcare provider is recommended.
Individuals on medication
Matcha's compounds can interact with various medications. For example, it may affect blood pressure, stimulant, or sedative drugs. Interactions with certain supplements, like calcium, magnesium, and folate, have also been identified. It is essential to consult a doctor if you take prescription medications.
Comparison: Matcha vs. Coffee side effects
| Feature | Matcha | Coffee |
|---|---|---|
| Caffeine Jitters | Less common, thanks to L-theanine creating calm focus and sustained energy. | More common, with a rapid spike and crash, especially in high doses. |
| Stomach Irritation | Possible due to tannins and caffeine, especially on an empty stomach, but generally gentler than coffee. | More acidic, which can cause significant stomach upset and reflux in many people. |
| Nutrient Absorption | Catechins and tannins can interfere with iron and folate; best consumed away from meals. | Tannins can also affect iron absorption, though matcha's effect might be more pronounced due to consuming the whole leaf. |
| Contamination Risk | Higher risk if sourcing is poor, as the whole leaf is consumed, potentially ingesting heavy metals and pesticides. | Lower risk from contaminants since the leaves are not consumed; risks are primarily from pesticides. |
Conclusion
While matcha offers numerous health benefits, potential risks and side effects exist and are often linked to overconsumption, low-quality products, and individual sensitivity. These range from caffeine-related issues like anxiety and insomnia to digestive upset and the presence of heavy metal contaminants. To minimize these risks, moderation is key, with 1 to 2 cups daily being a standard recommendation for most healthy adults. Selecting ceremonial-grade matcha from a reputable, certified source that provides third-party testing for heavy metals and pesticides is paramount. By being mindful of your intake and choosing quality products, you can enjoy matcha's advantages while avoiding the potential pitfalls. Always consult a healthcare professional regarding any dietary changes, especially if you are pregnant, breastfeeding, or on medication.
For more information on the safety of green tea catechins, refer to the EFSA Journal.
