Researchers wanted to know if matcha green tea—a popular powdered tea—could interfere with nadolol, a common heart medication. They tested this in rats by giving some animals matcha tea before the medication and measuring how the body processed the drug. The good news: a single dose of matcha didn’t cause problems. Even taking matcha daily for three weeks showed only minor changes in how the body handled the medication, and these changes weren’t statistically significant. However, the medication did stay in the body slightly longer with regular matcha use. Scientists say more research is needed before we know if this matters for people taking both together.
The Quick Take
- What they studied: Whether matcha green tea changes how the body absorbs and processes nadolol, a medication used to treat high blood pressure and heart conditions.
- Who participated: 32 male rats divided into four groups: one control group, one getting a single matcha dose, one getting a known drug interaction (itraconazole) as a comparison, and one getting matcha daily for 21 days.
- Key finding: A single matcha dose had no meaningful effect on nadolol. Daily matcha for three weeks caused the medication to stay in the body about twice as long (7.7 hours instead of 4 hours), but this difference wasn’t statistically significant for most measurements.
- What it means for you: If you take nadolol and drink matcha tea occasionally, there’s likely no problem. However, if you consume matcha regularly and take nadolol, talk to your doctor—the medication may stay in your system longer, though we don’t yet know if this causes real health concerns.
The Research Details
Scientists used 32 male rats and divided them into four groups to test different scenarios. Group 1 received only the heart medication (nadolol) as a baseline. Group 2 got a single dose of matcha powder mixed with salt water, then the medication 30 minutes later. Group 3 received itraconazole (a known medication that interferes with nadolol) to prove the test could detect interactions. Group 4 received matcha powder daily for 21 days before getting the medication. The researchers collected blood samples at 11 different time points over 24 hours and measured how much nadolol was in the blood using specialized laboratory equipment (HPLC-FL). They used another test (HPLC-UV) to verify the matcha quality by measuring its caffeine content.
This research approach matters because matcha is increasingly popular, and many people take it without knowing if it could interfere with their medications. By testing in animals first, scientists can safely explore potential interactions before recommending anything to humans. The study included a positive control group (itraconazole) to prove the test could actually detect interactions, which strengthens confidence in the results.
The study was well-designed with proper controls and used validated laboratory methods. The positive control group (itraconazole) successfully showed an interaction, proving the test could detect real effects. However, this was an animal study using rats, not humans, so results may not directly apply to people. The sample size (32 rats) is reasonable for this type of research. The study was published in PLoS ONE, a peer-reviewed journal, which means other scientists reviewed it before publication.
What the Results Show
When rats received a single dose of matcha followed by nadolol, there were no meaningful changes in how the body processed the medication compared to the control group. The amount of medication in the bloodstream, how quickly it peaked, and how long it stayed in the system were all similar to the control group. This suggests that occasional matcha consumption probably won’t interfere with nadolol. When rats received matcha daily for 21 days before getting nadolol, the results were more interesting. The peak amount of medication in the blood increased by about 45%, and the total amount of medication in the body over time increased by 18-22%. However, these increases were not statistically significant, meaning they could have happened by chance. The one statistically significant finding was that nadolol’s half-life (the time it takes for half the medication to leave the body) nearly doubled, from 4 hours to 7.7 hours.
The researchers confirmed their test was working properly by showing that itraconazole (a known medication interaction) significantly increased nadolol levels in the blood, as expected. They also verified the matcha quality by measuring caffeine content at about 4.2% by weight, which is consistent with typical matcha products. These quality checks strengthen confidence in the study’s validity.
This is the first study to examine the interaction between matcha tea and nadolol specifically. Previous research has shown that matcha contains compounds called catechins that can affect how the body transports certain medications. This study tested whether that theoretical concern translates to a real problem with nadolol, and found minimal effects. The results suggest matcha’s interaction potential may be weaker than some other herbal supplements.
The biggest limitation is that this study used rats, not humans. Rats metabolize medications differently than people do, so results may not directly apply. The study used relatively high doses of matcha (250 mg/kg in rats), which may not match typical human consumption. The sample size of 32 rats is small, which means some real effects might have been missed. The study only looked at nadolol and didn’t test other heart medications. Finally, the researchers couldn’t determine why the medication stayed longer in the body with regular matcha use, so the practical importance remains unclear.
The Bottom Line
Based on this research (low to moderate confidence due to animal study): If you occasionally drink matcha tea and take nadolol, there’s likely no need to change anything. If you regularly consume matcha and take nadolol, discuss it with your doctor—the medication may stay in your system longer, though we don’t know if this causes problems. Don’t stop taking nadolol or matcha without medical guidance. More human studies are needed before definitive safety recommendations can be made.
This research matters most for people taking nadolol (a beta-blocker used for high blood pressure, heart disease, and migraines) who also consume matcha tea regularly. It’s less relevant for people who drink matcha occasionally or those taking other heart medications. People with heart conditions should be especially cautious about any potential medication interactions.
If matcha does affect nadolol in humans, the effect would likely build up over weeks of regular consumption, similar to what happened in the 21-day rat study. You wouldn’t expect immediate changes from a single matcha drink. If you’re concerned, discuss monitoring options with your doctor.
Want to Apply This Research?
- If you take nadolol and consume matcha regularly, track your matcha intake (cups per week) and any symptoms like dizziness, fatigue, or irregular heartbeat. Note the timing of matcha consumption relative to medication doses.
- Use the app to log matcha consumption and nadolol doses separately, noting the time gap between them. This creates a record to discuss with your doctor if you experience any unusual symptoms.
- Set weekly reminders to check in on how you’re feeling if you consume both matcha and nadolol. Track heart rate, blood pressure (if you monitor it), and any side effects. Share this data with your healthcare provider at regular checkups to ensure the combination remains safe for you.
This study was conducted in rats and has not been tested in humans. The findings do not constitute medical advice. If you take nadolol or any prescription medication and consume matcha tea, consult your doctor or pharmacist before making any changes to your routine. Do not stop taking prescribed medications without medical guidance. This research suggests matcha may have minimal interaction with nadolol, but more human studies are needed. Individual responses may vary based on genetics, health conditions, and other medications.