Food, supplement, and medication interactions are more common—and more nuanced—than many clinicians realize.
Everyday foods and supplements can quietly alter drug effectiveness or safety – and often go unrecognized in practice. Grapefruit juice, orange juice, and green tea extract are just a few examples that may have more clinical significance than expected.
In this episode, NatMed editors Jeff Langford, Andrea Stafford, and Kelly Daniels break down clinically relevant interactions using atorvastatin as a case study—and show how to apply a practical framework for identifying, interpreting, and managing these interactions at the point of care.
Questions we answer in this episode:
- Which common beverages, foods, and supplements interact with atorvastatin – and how do they affect the drug?
- How do interactions differ between increased drug levels (toxicity risk) vs reduced drug effectiveness?
- When should clinicians recommend avoidance vs timing adjustments vs monitoring?
- How can clinicians identify interactions patients don’t think to mention in routine conversations?
🏷️ Our listeners can get 10% off a new or upgraded subscription with code natmed1026b at checkout.
NatMed / TRC Healthcare Editor Hosts:
- Jeff Langford PharmD, BCPS, BCCP (Managing Clinical Editor)
- Andrea Stafford, PharmD (Assistant Editor)
- Kelly Daniels, BA (News Editor & Associate Content Manager)
Guest:
- Cathi Dennehy, PharmD, FCSHP (Health Sciences Professor of Clinical Pharmacy, UCSF School of Pharmacy)
CE Information:
This podcast is sourced from the NatMed June 2026 Newsletter. To claim CE credit, subscribers should read the newsletter and click “Take the CE Quiz” link to take the quiz.
The clinical resources mentioned during the podcast are part of a subscription to NatMed:
- 🌱 NatMed Pro
- 💊 TRC Healthcare
- Newsletter
- Interaction Checker
- Monograph: Grapefruit
- Monograph: Green Tea
- Monograph: Orange Juice
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The content of this podcast is not intended to be a substitute for professional medical advice, diagnosis, or treatment.
Natural Medicines: Evidence in Practice is a production of TRC Healthcare.
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Transcript:
Introduction
Jeff Langford 0:04
If a patient on atorvastatin asks, can I drink grapefruit juice with this med? Most clinicians feel pretty confident answering that.
Andrea Stafford 0:12
But what about green tea or orange juice? And more importantly, how do you know you’re catching all the interactions that actually matter?
Jeff Langford 0:20
Well, welcome back to Natural Medicines Evidence in Practice. I’m Jeff Langford, a pharmacist and managing editor at NatMed.
Andrea Stafford 0:26
And I’m Andrea Stafford, a pharmacist and assistant editor. And I’m Kelly Daniels, news editor and associate content manager.
Jeff Langford 0:33
And on this show, we’re going to cut through the noise and trends to bring you practical and evidence-based guidance.
Andrea Stafford 0:38
And today we’re using atorvastatin interactions with foods and supplements as a starting point.
Jeff Langford 0:45
Yes, because this is a window into a much bigger issue, how foods, supplements, and meds can interact and how easily that can be missed in clinical practice.
Kelly Daniels 0:54
And not just the ones everyone knows, like grapefruit, but the less obvious ones that can still impact safety and effectiveness.
Andrea Stafford 1:01
And we’ll walk through a few key examples and discuss how we can apply it in practice.
Kelly Daniels 1:05
And CE credit is available for our podcast through our monthly Nat Med newsletter. Plus, we just released a new full CE course on drug supplement interactions that goes much deeper. Check the show notes for details.
Jeff Langford 1:17
So,
Why Interactions Are Missed
Jeff Langford 1:18
Andrea, you know my question is coming. Why are we focusing on this today?
Andrea Stafford 1:23
Well, that’s because atorvastatin is the most prescribed medication in the United States. And we know that interactions with foods and supplements are always a concern in general.
Kelly Daniels 1:34
Plus, social media is full of buzz about the natural medicine’s benefits, but discussions about possible interactions are really much less common. And they can be very easy to overlook, partly because patients don’t always think of foods or supplements as something that can even interact in the first place.
Jeff Langford 1:51
Yeah, they might expect a drug-drug interaction or even proactively ask about that, but they might not be thinking about what they drink, eat, or even consume over the counter could impact their medications.
Andrea Stafford 2:03
Right. And so you might hear things like this coming from patients saying, oh, I started drinking green tea recently, or I’m trying to eat healthier, or I’ve added a supplement, which all of those can mean very different things.
Jeff Langford 2:16
Yeah, they don’t sound like an interaction risk, but they might be.
Kelly Daniels 2:20
Right. And that’s what makes this tricky. These might already be part of a patient’s daily routine. So they’re not obvious red flags to bring up.
Andrea Stafford 2:28
And when you actually look at the data, even for something like atorvastatin, there are several clinically relevant interactions.
Jeff Langford 2:36
Right. They span foods, supplements, herbals, and really across multiple different mechanisms of interactions as well, Andrea.
Interaction Pathways
Jeff Langford 2:44
But before we get into these specific examples, let’s kind of step back a minute and look at some of those mechanisms. And will you walk us through some of the different types of mechanisms we might encounter in these atorvastatin interactions, Andrea?
Andrea Stafford 2:57
Yes. And so I’m going to look at this and kind of talk about it at a very high level. And most of what we’re talking about today specifically falls into one of the following pathways. There’s metabolism effects, where a substance interferes with how a medication is broken down, typically by inhibiting or inducing a key enzyme like CYP3A4. We also have an effect called transporter effects, which affect how drugs move into or out of cells. For example, a substance may inhibit or induce transporters like organic anion transporting polypeptides or OATPs. And then we can also have something with absorption or timing issues, where a substance changes how much drug actually gets absorbed. And just to make a quick note, some of these medications may be affected by more than one of these pathways.
Jeff Langford 3:50
Okay, Andrea. That’s a really good nice framework. Of course, we’re not covering all possible types of drug interactions, but we’re saying three big categories are effects on metabolism, transport, or something to do with kinetics. And those things could turn up or turn down a drug level potentially, could go in any direction, right?
Andrea Stafford 4:06
Exactly. Yeah.
Jeff Langford 4:08
So if we just can keep a general framework like that in mind, I think it’s going to help us kind of slot some of the key drug interactions into how they work and make them a little bit more memorable in practice.
Andrea Stafford 4:18
Yes.
Grapefruit Interaction
Andrea Stafford 4:19
So let’s start with a food interaction that most clinicians are probably already familiar with, which is grapefruit.
Jeff Langford 4:26
And it does get a lot of attention.
Kelly Daniels 4:28
Which would explain why it’s one patients usually know as well.
Jeff Langford 4:31
And a key point here is that this is a major interaction, but it’s also a really common food.
Andrea Stafford 4:37
Yes. So something as routine or as common as a glass of grapefruit juice can interfere with how atorvastatin gets metabolized. Grapefruit contains furanocoumarins that inhibit CYP3A4 in the intestines, which reduces the drug’s breakdown, meaning atorvastatin levels increase, raising the risk for adverse effects like increased muscle pain.
Jeff Langford 5:02
I think it’s important to call out that this interaction with grapefruit and atorvastatin isn’t just with atorvastatin. It can occur with lovastatin or symvastatin in the same family. But it doesn’t happen with all statins. There are drugs that aren’t metabolized through this pathway, like pravastatin and rosevastatin. So just a little pharmacy call out there as we think about how to manage it.
Andrea Stafford 5:23
Yes. And with any of these satins that are metabolized by CIP3A4, one misconception that we need to be clear on is that we can’t just space them out, meaning we eat grapefruit in the morning and then we take our atorvastatin at night. Because grapefruit’s effect on CIP3A4 can last up to 48 hours. So separating them doesn’t avoid this interaction.
Kelly Daniels 5:46
Yeah, 48 hours is a long time. So this doesn’t sound like one you can just work around.
Jeff Langford 5:51
Yeah, that’s right, Kelly. This really is not a matter of timing grapefruit consumption, but it’s really generally avoiding grapefruit, especially for people that like to consume it routinely.
Andrea Stafford 6:02
And kind of with that nuance, stay tuned because there are some additional nuances that we’re going to talk about a little bit later. But for now,
Green Tea Interaction
Andrea Stafford 6:10
let’s shift to something a little less obvious, like green tea. Wait, just like drinking green tea?
Jeff Langford 6:17
That’s a good question. And this is where it gets a little fuzzy. Most of the data are on green tea extract. The data are much less clear about brewed green tea.
Andrea Stafford 6:27
Yes, and that’s because green tea has catechins that can reduce atorvastatin levels via the inhibition of that Oat P transporter, meaning less drug crosses from the gut into circulation, leading to a reduced drug effect.
Kelly Daniels 6:42
So this is the opposite of grapefruit. Instead of too much drug, we might actually have not enough drug.
Jeff Langford 6:48
Yeah, exactly. And that’s part of what can make it harder to detect. We’re not looking for toxicity or harmful side effects. We’re maybe reducing effectiveness and that might be easier to miss.
Andrea Stafford 7:00
And in clinical studies, taking a green tea extract supplement in a dose of either 300 milligrams or 600 milligrams with atorvastatin, it reduced the levels by about 24%.
Kelly Daniels 7:14
But the tricky part here is that a lot of patients might not even think of mentioning this. You know, you have a healthy cup of green tea in the morning that doesn’t raise any red flags to mention as a drug interaction concern.
Andrea Stafford 7:26
You’re right. And it’s not even clear whether regular brew green tea has that same effect.
Jeff Langford 7:32
So with green tea extract supplements, our guidance is going to be to avoid the combination of a green tea extract with atorvastatin. But if it’s a patient who just drinks green tea, the data, again, are lacking. So we’re going to use caution. For instance, we might need to consider how much and how often they’re consuming green tea.
Andrea Stafford 7:50
I think Jeff brings up an excellent point on that nuance there. And so, kind of like grapefruit, we’re going to come back to that in a few minutes. The big takeaway is that with grapefruit juice and green tea extract supplements, we generally want to avoid them with atorvastatin.
Orange Juice Interaction
Andrea Stafford 8:07
But there is an interaction we want to discuss where the guidance isn’t necessarily to avoid, but it’s more about timing.
Kelly Daniels 8:14
Interesting. So the approach sounds different here. Is this interaction one most clinicians and patients know about?
Jeff Langford 8:20
I think this might surprise some people, Kelly. It’s orange juice. Okay.
Kelly Daniels 8:25
Definitely would not have thought of that one.
Andrea Stafford 8:27
You’re not alone. This isn’t likely to be on many people’s radar, Kelly, but orange juice contains flavonoids that inhibit those OP transporters. So less atorvastatin gets absorbed.
Kelly Daniels 8:39
So again, this is more about the drug not working as well if you take it with orange juice.
Jeff Langford 8:45
Potentially, yes. And so timing can matter in this case.
Andrea Stafford 8:49
Yes. This isn’t necessarily something patients have to avoid completely, but patients do need to separate orange juice and atorvastatin by at least four hours.
Jeff Langford 9:00
And we’ve seen this effect with some other drugs like fexofenadine, where orange juice can reduce absorption. It’s likely a similar process here with atorvastatin and orange juice.
Kelly Daniels 9:11
So this is where the conversation shifts. It’s less about don’t combine this food and medication and more about here’s how we can manage this safely. Exactly.
All Juices?
Kelly Daniels 9:20
Okay, so I guess as a patient, you know, we covered green tea, orange juice, and grapefruit juice. Should patients be wondering if they should just avoid juices?
Jeff Langford 9:31
Yeah. Good question, Kelly. I think what we really have to think about here is considering the specific drug that they’re taking or drugs. Most people aren’t on just one, and recognizing that these interactions are very specific to the constituents, like Andrea mentioned, that are in the juices. She talked about those really fancy words like catechins and furanocoumarins. And so that’s dependent on the fruit and the juice and the product and all of those things. So that’s again going to turn us back to let’s just get the information, let’s go to a resource like NatMed and find the answer.
Andrea Stafford 10:03
And to just kind of add to Jeff’s great information that he provided us in that interaction with a patient at a counter, if they’re asking about something more specific about pomegranate juice, that gives us that excellent opportunity to pull up natural medicine and look at what the clinical data tells us because not every juice has been studied with every medication. And so being able to use that resource and give them that information at point of care is imperative.
Jeff Langford 10:29
And I think we can reassure people that it’s not everything. They don’t have to run away from the juice aisle in the store. Just come ask us a question and we’ll help them get to the right answer.
Andrea Stafford 10:37
Yes.
NatMed Tools and Resources
Jeff Langford 10:41
And the reality is there are many more interactions we didn’t discuss today.
Kelly Daniels 10:45
And there’s no way you’re keeping all of that in your head.
Andrea Stafford 10:48
No. And as a pharmacist in a community setting, I can say firsthand this is very true. It quickly becomes more than I can realistically kind of keep track of in my memory, especially when patients mention foods andor supplements and that quick counter interaction.
Jeff Langford 11:04
Yeah, and that’s where tools like our NatMed interaction checker come in. And you can pull up that information in real time quickly and actually see what’s clinically relevant.
Kelly Daniels 11:14
Plus, we have our monthly NatMed newsletter for ongoing updates and clinical pearls.
Andrea Stafford 11:19
And our listeners can save 10% with code NATMED1026 at checkout. Links to everything we’ve discussed are in the show notes.
Expert Interview – Cathi Dennehy
Jeff Langford 11:34
Okay. Joining us now to talk through some of the nuance around managing these interactions in practice is Dr. Cathi Dennehy, Clinical Professor of Pharmacy at University of California, San Francisco, with expertise in dietary supplements and drug interactions. Cathi, welcome. We’re excited to have you with us today.
Cathi Dennehy 11:51
Thank you. I’m also excited to be here.
Jeff Langford 11:55
Yes, it’s a great conversation and I think a really fun topic that is important for clinicians of all stripes. Before we get into some of the specifics about managing these atorvastatin interactions that we’ve been talking about, I want to kind of step back and address a challenge that I think clinicians often face. The fact that patients don’t always disclose what they’re taking. They may not consider, for example, that green tea extract supplement or an orange juice with breakfast relevant to a medication conversation. And so I’m kind of wondering in your practice, what strategies do you utilize or perhaps teach your students to help us get a fuller picture from patients about foods, meds, and supplements that may be relevant?
Cathi Dennehy 12:37
Yeah, it’s a great question, Jeff. I think it also depends on the patient’s medical history in terms of how deep you go into dietary factors that could affect drug therapy. For example, if a patient had a known history of diabetes, you would be more inclined to ask them about do you drink fruit juices? And if so, how much and how often? As a pharmacist, you know, where we know of an interaction. As an example, I work in an anticoagulation clinic and I’m well aware that green tea can interact with warfarin. And so in my clinical setting, I will ask patients specifically about green tea, about other plant-based products that they might be taking that can also interact with warfarin. But in terms of other foods and other interactions that might exist, I really do believe it’s provider-dependent. It’s also based on your area of specialization.
Jeff Langford 13:39
Okay. So I think it’s probably fair to say that there often may be some gaps in obtaining that complete dietary picture. Again, depending on who it is and why the patient is being expected.
Cathi Dennehy 13:51
Exactly.
Jeff Langford 13:52
Okay. Well, that’s good context for us as we figure out how to identify, first of all, these interactions and how to manage them if they do bubble up on our radar. So let’s dig into atorvastatin just a bit and think about some of these interactions that we’ve talked about, acknowledging that recognizing them is going to be important, first of all. Grapefruit, of course, I think for years has been on people’s radar. So that one is probably a little easier to tease out. But our recommendation when we talked about this earlier is that we would like to avoid the combination of atorvastatin and grapefruit juice. But I wonder what other factors beyond that kind of high-level headline recommendation you might take into consideration to make a more patient-specific recommendation. I guess I think of the avoid being like at the population level, and then we’ve got the patient in front of us. And how do we dial that in?
Cathi Dennehy 14:43
Well, this is one where the interaction specifically with grapefruit is one that’s considered irreversible. So it’s something where it’s happening at the intestinal level where you’re actually irreversibly inhibiting enzymes that are involved in drug metabolism, something called first pass metabolism. And so if you’re knocking those out, more drug is getting in. And so you’re going to have higher drug levels or a higher drug effect for atorvastatin, if you will, which could increase the risk of potential side effects like muscle pain or possibly rhabdomyolysis. So when it comes to that, I would, you know, obviously each person is going to be different in how they advise a patient. In general, I would say it’s better to avoid it because it’s an irreversible interaction. I would say there’s probably some other juices that we can discuss that you would like very much and that don’t have this effect. Maybe we should talk about some of those. And that’s that’s where how I would steer that.
Jeff Langford 15:43
That’s really helpful. But with things like green tea extract or orange juice, the interaction concern is less about side effects and more about reducing the clinical effect of atorvastatin. So how do you think about those kind of interactions in practice?
Cathi Dennehy 16:00
Yeah, great question, Jeff, because when you’re decreasing a drug effect, you’re talking about clinical effectiveness, right? And in terms of clinical effectiveness, where we have a drug that we can monitor effectiveness using lab work, we’re going to do that. You know, thankfully for something like a statin drug, like atorvastatin, we can monitor HDL, LDL, total cholesterol. So we have parameters that we can follow to know is it having an effect? When I think of, here’s here’s a great example. When I think of where I work in the anticoagulation clinic, I have patients who they say, well, look, part of my lifestyle is I like to have green smoothies. And this is something that it’s not negotiable for me. And we know that the green smoothies are going to decrease the effect of the warfarin because of the vitamin K content. And I say, I can work with that. What I’m going to do is I’m going to adjust the dose of the medication to account for your diet. But you have to do me a favor. And the favor I’m asking you to do is to keep your dietary intake of this ingredient steady so that I can adjust the dose of the drug to accommodate your diet. And I think that’s a great example of what we’re talking about here.
Jeff Langford 17:24
That’s a great example, Cathi. When you can monitor and adjust, consistency becomes a key part of the counseling. As we wrap up, what habits do you like to teach trainees that help them work through these interaction decisions in practice?
Cathi Dennehy 17:39
So with every patient that we have, we always ask if the patient would be interested in a medication review. We always do an interaction check as part of that, but predominantly we’re looking for interactions between the medications. We’re not, you know, not as frequently putting in a juice or a particular food-based product, but we do use NAT Med database to do checks for interactions between our medications and supplements that the patient is taking. So we are consistently looking for those on a daily basis, I would say, in clinical practice. And I think where we know of a potential interaction with a food-based product, again, we’d be looking at getting a broader dietary intake history, how much, how often, recognizing that there’s variability patient to patient in terms of how they respond to a particular food and how their enzyme levels might respond. And we get a nutritionist consult where we see that that would benefit a patient. If we think that there is something that a nutritionist who’s much more broadly schooled in food-based health education, potentially those interactions, we’ll bring in that, uh, you know, we’ll ask for a consult, we’ll bring in the nutritionist, we’ll see what the nutritionist has to say, and we’ll integrate that. That’s the beauty of interprofessionalism. It’s recognizing that you as a single healthcare provider, me and my, you know, my health discipline of pharmacy, there’s knowledge that I have, but there’s knowledge that others have that could be brought in to supplement and to complement and to really enrich the education that we’re providing to every patient. That’s my hope.
Jeff Langford 19:38
Absolutely. I love those points, Cathi. This has been a great conversation. I think key takeaways that we can uh leave that with are that you know, really integrating a consistent practice of evaluating interactions with drugs across a broad range of things and having that awareness of the potential for foods to interact and having a reliable source, like you mentioned in your clinic using the NatMed interaction checker, where we can help to fare it out and get more information when we need to. So, some great tips that people can take right back into practice and as they work with trainees and patients. Well, thank you so much, Cathi. I appreciate your time and your expertise today.
Cathi Dennehy 20:18
Thank you. It’s been a, my pleasure being here and being a part of your podcast. Thank you sincerely.
Kelly Daniels 20:24
Well,
Final Takeaways
Kelly Daniels 20:25
that was so great to hear from Dr. Dennehy and to hear that the NatMed Interactions Checker is being used in real time to teach students and to treat patients.
Andrea Stafford 20:33
Yes, and I think she also emphasized to be patient specific and really take that time to speak with patients and kind of understand where they’re at and how important something is to them.
Kelly Daniels 20:44
And from the patient side, just to spread awareness that these are things you should maybe bring up to your provider, even if you think it’s not important, it actually might, it might be. Yeah.
Jeff Langford 20:54
And I think as we’ve talked a lot today about the nuance around managing these drug interactions, I think it’s important to keep in mind the the ratings on these things are really at the population level. They’re saying generally avoid, or it’s probably not that important. But we really do have to take into account like how old is that patient? How much drug dose are they taking? What’s the rest of their medication profile look like? Uh, and to kind of factor all of that into how important an interaction is and really make a very patient-specific interpretation of that rating to help the patient achieve the best possible outcomes.
A Few More Things…
Jeff Langford 21:30
Okay. And if you want to dive deeper into this, we’ve linked the CE, the newsletter article, and the tools we mentioned in the show notes.
Kelly Daniels 21:37
Also in the June newsletter, we cover some other interesting and timely topics, including creatine’s role in mental health, weight loss alternatives to consider. And in our most recently published July newsletter, we dive into what is Ube and why are people using it, and what clinicians need to know about nattokinase.
Andrea Stafford 21:54
So follow and subscribe to the show in your podcast app so new episodes land automatically.
Jeff Langford 21:59
Thanks for listening to Natural Medicines Evidence in Practice. It’s evidence, not hype.
Andrea Stafford 22:04
And we’ll see you next month.
Natural Medicines: Evidence in Practice
