Caffeine-related side effects
Matcha contains a significant amount of caffeine, more than regular green tea and potentially comparable to a shot of espresso per serving. While the amino acid L-theanine tempers the typical coffee-like jitters, providing a state of "calm alertness," consuming too much can still lead to undesirable effects, particularly in caffeine-sensitive individuals.
Common caffeine-related issues include:
- Anxiety and jitters: Excessive caffeine can overstimulate the nervous system, exacerbating feelings of anxiety, nervousness, and restlessness.
- Sleep disruption: Drinking matcha late in the day can interfere with sleep patterns and cause insomnia, even in those less sensitive to caffeine.
- Increased heart rate and blood pressure: High caffeine intake may cause heart palpitations and temporarily elevate blood pressure, which is a concern for people with heart conditions.
Digestive problems
Certain compounds in matcha, such as tannins and catechins, can cause digestive upset if consumed in large quantities or on an empty stomach. This is because tannins can irritate the stomach lining and increase acidity.
Digestive symptoms can include:
- Nausea and upset stomach: Often triggered when drinking matcha on an empty stomach, the tannins and acidity can lead to a queasy feeling.
- Diarrhea or constipation: The high fiber and caffeine content can have a laxative effect for some, while the astringent quality of tannins can lead to constipation in others.
- Acid reflux and heartburn: Increased stomach acid production can worsen symptoms for those with gastritis, ulcers, or GERD.
Risk of heavy metal contamination
Since matcha involves consuming the entire green tea leaf in powdered form, any contaminants present in the leaves or soil are also ingested. Tea plants are known to absorb heavy metals like lead and arsenic from their environment. The quality and origin of the matcha are critical factors in mitigating this risk.
Contamination concerns are especially high with low-quality, unregulated, and untested products, particularly from certain regions like China, where studies have found higher levels of lead in some tea products. Reputable Japanese producers, in contrast, often adhere to stricter safety regulations and testing protocols, yielding a safer, higher-quality product. Always choose organic, tested matcha from a trusted source to minimize heavy metal exposure.
Interference with nutrient absorption and medication
The compounds in matcha can interact with the body's absorption of certain minerals and the effectiveness of some medications.
- Iron absorption: The tannins in matcha can bind to non-heme iron (from plant-based foods), making it harder for the body to absorb. Those with anemia or at risk for iron deficiency should avoid drinking matcha with meals.
- Medication interactions: The high concentration of catechins in matcha can interact with certain medications, including blood thinners, cholesterol-lowering drugs, and blood pressure medications. Consult a doctor to determine if matcha is safe to consume alongside your medication regimen.
- Liver considerations: In very rare cases, extremely high doses of green tea extract (not typically from drinking tea) have been associated with liver toxicity. This risk is generally associated with concentrated supplements, but it is still wise for individuals with liver disease to consult a healthcare provider.
Matcha quality vs. drawbacks
Quality plays a significant role in determining potential downsides. A low-quality, less vibrant matcha may contain more tannins and heavy metals, leading to more pronounced side effects.
| Feature | High-Quality (Ceremonial Grade) | Low-Quality (Culinary Grade) |
|---|---|---|
| Sourcing & Purity | Typically from Japan, with stringent testing for heavy metals and pesticides. | Often from less regulated areas; potential for contaminants. |
| Flavor Profile | Sweet, mellow, and less bitter due to younger leaves and higher L-theanine. | More astringent and bitter from older leaves and fewer beneficial compounds. |
| Caffeine Impact | L-theanine provides a smoother, longer-lasting energy boost with fewer jitters. | Often contains more raw, unmitigated caffeine that can cause jitters. |
| Digestive Impact | Less likely to cause nausea or upset stomach due to lower tannin content. | Higher tannin levels may irritate the stomach, especially on an empty stomach. |
| Cost | More expensive due to delicate processing and higher standards. | Cheaper due to less meticulous sourcing and processing. |
Conclusion: Moderation is key
While matcha is lauded for its health benefits, understanding its potential downsides is essential for responsible consumption. The primary risks are linked to overconsumption, low-quality products, and individual sensitivity to caffeine or tannins. To minimize these negatives, choose high-quality, reputable matcha brands and consume in moderation, typically 1–2 cups per day. If you have pre-existing health conditions or take medications, consult a doctor before incorporating matcha into your daily routine. With mindful consumption, most people can enjoy the benefits of matcha without experiencing the drawbacks. Read more on responsible consumption here.
