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The Dose Transcript for April 26, 2023

Host: Dr. Brian Goldman

STORIES FROM THIS EPISODE

BRIAN GOLDMAN: I'm Dr. Brian Goldman. Welcome to the dose. Coffee has been a big part of my daily routine since I was a teenager. Today, it helps me stay awake on night shifts. And I have to tell you that I pay extra attention every time a study suggests that caffeine benefits your health one way or another or your exercise routine. So this week we're asking, how does drinking coffee affect my health? Hi, Thomas. Welcome to The Dose.

THOMAS MERRITT: Hi, Brian. How are you?

BRIAN GOLDMAN: I am just fine because I am well caffeinated. Are you well caffeinated?

THOMAS MERRITT: I am. I am in a motel. And so my delivery mechanism for the caffeine is not what I'm used to, but I've got a nice sort of semi warm cup of coffee in my hand.

BRIAN GOLDMAN: So what is your coffee routine?

THOMAS MERRITT: I love espresso. I've got an espresso maker in my office. I've got an espresso maker at home. I am a huge fan of pour over. So I get up every morning, grind some beans, put it in a funnel, a little paper filter, and I make about a cup of coffee. And so I really like that ritual of making a cup of coffee. If I want a second cup of coffee, I make a second cup of coffee. But I really enjoy the sort of art of making that coffee.

BRIAN GOLDMAN: Yeah, art to making coffee. So I, you know, until you told me what a pour over is, I didn't realize that I've been doing a pour over for about 40 or 50 years. Yeah, I'm a pour over guy. I make a strong brew first thing in the morning, and I put a lot of ground beans into that paper filter and not all that much water, because I want a good hit of caffeine, too, to get me started in the morning. Okay, so you're the right guy to talk to. Before we begin, can you give us a. Hi, my name is tell us what you do and where you do it. Just ad lib.

THOMAS MERRITT: Sure. My name is Thomas Merritt. I'm a professor at the University in the School of Natural Sciences. Most of what I do is I use fruit flies to study genetics and stress. A lot of what I do as I write and talk about the science of coffee.

BRIAN GOLDMAN: Do fruit flies consume caffeine?

THOMAS MERRITT: So, they don't. But, you know, caffeine is we we drink it in a beverage, but it is a natural product. And there's a really interesting story of the biology of caffeine. I use it because lots of people drink coffee, but it depends on who's doing the math. It's the most commonly consumed beverage in the world. And if you want to talk to people about science, talking to them where they live is a great way to do that. So if I talk to them about fruit flies and stress, people send a glaze over a bit. If I talk to them about that cup of coffee they started the day with, people get really excited about it. So I use this as a way to engage people in science.

BRIAN GOLDMAN: Okay, let's get to the serious side of this from a plant and chemical perspective. What exactly do we mean by coffee?

THOMAS MERRITT: Yeah, so that is a really cool question. So caffeine is the molecule that most of us think of with coffee. Coffee is a complex beverage. There are thousands of different molecules in a cup of coffee. The one that we react to, the one that wakes us up is caffeine. We don't exactly know the biology of caffeine, what the natural function of caffeine is. There are a couple of models. The best guess is it's found in coffee, it's found in tea, it's found in a handful of other plants. And we think that it's actually part of the plant's mechanism to prevent insects from eating it. So it essentially slows caterpillars down where it taste bitter and the caterpillar doesn't eat the leaf. And that's sort of the reigning theory of why we have caffeine, how we have caffeine in nature.

BRIAN GOLDMAN: So how.. so at the chemical level, at the molecular level, how does caffeine wake us up?

THOMAS MERRITT: Yeah, so that's another question altogether. So we have basically co-opted what we think is a plant toxin as a stimulant to wake us up. And actually as human beings, we're really good at co-opting molecules that have evolved to do one thing, to do something else. One of those molecules is caffeine. Caffeine is a ring molecule. It's a bunch of carbons and a ring structure. It looks a lot like adenosine, which is a naturally occurring neurotransmitter in us. Adenosine is involved with keeping us drowsy, keeping us asleep. It's called adenosine tonic. And caffeine looks enough like adenosine that it binds to a set of adenosine receptors. And it looks just different enough from adenosine that although it binds to the receptor, it doesn't fire off the typical cascade that keeps us asleep. And so it breaks that normal sleep cascade and breaks that cycle, and it actually fires off a different cascade that leads to a series of things, one of which is waking us up. So you drink a cup of coffee, you ingest those thousands of molecules, caffeine gets into your blood, goes from your blood to nerves, and your brain binds to an adenosine receptor, turns off that sleep pathway and turns on a wake up pathway.

BRIAN GOLDMAN: So by doing that, does it help make us more alert? Is it the same mechanism?

THOMAS MERRITT: Yeah, it is. And so you're basically you're breaking that drowsiness cycle. You're waking yourself up. You're also hitting the dopamine cycle and dopamine comes up a lot. We talk about human biology. It's the same neurotransmitter that's involved with why does sex feel good? So if wait to drink a cup of coffee does wake you up, but it has this euphoric effect to it. In addition to just that buzz of a cup of coffee.

BRIAN GOLDMAN: There is something about, you know, as as a long term drinker of coffee. And, you know, there are times when I've had more cups of coffee. You know, I find that two or three cups of coffee a day is about all I can take. And when I consume more than that and I have in the past, I just get more jittery and nervous and I don't get any more of the beneficial or pleasurable effects that I got from that first cup of coffee. Is there a pharmacological basis for that?

THOMAS MERRITT: Yeah, it certainly is. And then it goes beyond that. You can actually start to get more tired, so you can only put off that adenosine sort of tired drowsy pathway for so long. This is not a magic bullet. It's you're basically turning off a pathway that wants your body to relax, calm down, take it down a notch. We're using this to sort of jumpstart part of that morning routine. But the longer you're putting that off, the more there's sort of a baggage associated with that. And so you can get jittery and you're basically just sort of overloading your system. You know, the caffeine is mimicking a neurotransmitter. Too much of that is not a good thing. Fundamentally, when you talk about coffee and certain about coffee and tea, although there's a lot less caffeine in tea, you really are talking about ingesting a drug. Caffeine is the most common psychoactive drug, commonly used psychoactive drug in the planet. And we really need to think about it in those terms. And the numbers that you started this with, a really good general ballpark figure for most people in general, most people can tolerate one, two, three, maybe 1 to 4 cups of coffee over the course of a day. And most people beyond that, you start to get a little jittery and you really need to pay attention to that. And then, of course, there's some people that can pound back pot after pot with no adverse effects. And there's some people they have a sip of coffee and they get really amped up over jittery. So there's a lot of variation in how individuals respond to that cup of coffee.

BRIAN GOLDMAN: So different people respond differently to the same dose of caffeine. And we can also say that different cups of coffee contain different amounts of caffeine.

THOMAS MERRITT: And both of those are absolutely true. And we actually know quite a bit of the science of both of those. So the receptors that we have, they're different. Everybody has the same genes for the receptors. We have different forms of the genes, what we call alleles, and they're different alleles that are more or less caffeine sensitive. And we know that at the receptor level, and we think we know that beyond that in the molecular pathway. So there's a lot of variation individual to individual that's just genetic and it's your genetics make you either particularly robust and insensitive to caffeine or particularly sensitive to caffeine. And the receptor story is only half the story. You ingest the caffeine, but you also digest it, you break it down. And there's a lot of variation on that side, too. So there's variation in how you respond to caffeine and there's variation in how quickly you break down caffeine. And not surprisingly, the faster you break it down, the less you react to caffeine. So we know quite a bit about the biology of how individuals respond to that cup of coffee. The the interesting twist is the environment plays on top of that. So if it sounds like if like with you or with me, I start every day with a cup of coffee, I usually have a second cup of coffee and by the time I hit lunch, I'm usually somewhere around three or four, I'm going to respond to this coffee differently than somebody that has an occasional cup of coffee. So you really build up a tolerance.

BRIAN GOLDMAN: And and of course, since you mentioned, you know, developing a tolerance for caffeine, if you, for whatever reason, have to stop taking caffeine, you're going to notice withdrawal effects.

THOMAS MERRITT: Yeah. So there's a lot of debate as to whether caffeine, whether coffee. And really when we say coffee, we mean caffeine is addictive. It's certainly habit forming and you certainly develop a tolerance to it. And like you say, if you do anything that you've developed a chemical tolerance to, when you take it away, you can have adverse effects like headaches. So and you mentioned so I don't want to lose this in the conversation, you mentioned the idea that different different types of coffee I can't remember how you phrase it, but different types of coffee have different amounts of caffeine. Yeah, there's a really interesting biological story behind that. So 90% of the coffee that we consume is Arabica. So it's coffee. Arabica is the genus and species. There's another coffee, coffee Robusta or can of four, and it's a closely related ish coffee species that is also caffeinated and has more caffeine. So there are blends of coffee that blend in robusta to get a little extra kick in that cup of coffee.

BRIAN GOLDMAN: So there are still a lot of unknowns about the impact of caffeine. And it's hard to make generalizations because of this different individual variation in response to caffeine, how you how you metabolize it, how you how you digest it. But we have to try to come up with some generalizations. So, so what do we know today about the impact of caffeine on our health? Let's start with good or bad. Just just let me know.

THOMAS MERRITT: Yeah, So that's a really great question. And so one one of the things that we're pretty confident in is that most people can drink 1 to 4 cups of coffee a day, wake up a little bit in the morning, maybe stay awake a little bit in the afternoon and have absolutely no adverse health effects. We also know that there are some people that are particularly sensitive to caffeine and they shouldn't drink coffee. And we know that people there are certain people that are really insensitive to caffeine and they don't need to be thinking about limiting themselves to three or four cups of coffee. They can drink as much as you want. So those are two of the big picture broad generalizations. Most of us can drink 1 to 4 cups of coffee and you're fine.

BRIAN GOLDMAN: And from what you just said, how do you know it's affecting you adversely? Is it just that you get jittery and your heart rate goes up?

THOMAS MERRITT: Yeah. And so what we would love to be able to do is a genetic test. And they, like I said, there are alleles that are more available to the receptor. There are alleles of the enzyme that break it down that we can identify that we'd see as a population people that have this allele or that allele should be more or less conscious of the amount of caffeine that you read. And unfortunately the test isn't quite that cut and cut and dry. It's not like even something as complicated as eye color. That's. Relatively straightforward. I can't look at your genetics and tell you whether you should limit the amount of caffeine. What it really comes down to is you need to just pay attention and, you know, do you feel uncomfortable after a cup of coffee? Well, you should probably scale it back or think about something like a decaf coffee. And if you feel like you're waking up and you're still comfortable with the coffee after a couple of cups, that's great. You know, unfortunately, there is no simple solution. It really is a matter of using common sense and listening to your body as you drink the coffee.

BRIAN GOLDMAN: There are studies that suggest drinking coffee can lower your risk for heart disease. On the other hand, I can tell you that cardiologists will tell patients who have ischemia, heart disease, who have angina, not to drink caffeinated beverages, to switch to decaf if they've got high blood pressure. I say don't don't drink Caffeinated beverages strictly switch to decaf. So what do we know about all that?

THOMAS MERRITT: Yeah. So what we know is there's a lot of variation out there. We know there's a lot of interest. And the term that I love to use that's really unfortunate is delusionally optimistic. So there are so many of us that drink so much coffee that we would love there to be a health effect to cup to a cup of coffee. There is absolutely a positive social aspect. I am a better human being to talk to you if I've had a cup of coffee, but I'm not going to live, right? I mean, that's sort of like the bottle too. But I'm not going to live longer because I drink a cup of coffee and I'm probably not going to live any less long because I drink a cup of coffee. So the studies that have come back on either side, it seems to be, you know, every five years is another study. And a lot of the studies are incredibly well done. I mean, we're talking about, you know, controlled studies where they're specifically looking at caffeine ingestion that can involve thousands of people and then epidemiological broad scale things that we're talking about, tens or hundreds of thousands of people that have been surveyed. There's not really a clear answer that comes out of that. There's definitely a tie between caffeine and blood pressure. And so if there are some underlying things that your that you know about, you've got high blood pressure, you're prone to kidney disease is another one that caffeine tends to play into, then you need to be conscious of caffeine. But it's it's really not something that we can say to just your average person of the population. This is what we know about coffee and your biology. We know it'll wake you up. I don't think that we know it's going to make you live any longer or any less long.

BRIAN GOLDMAN: But if you do have high blood pressure, common sense says you should probably back off the caffeine, especially if if the more you drink, the higher your blood pressure is.

THOMAS MERRITT: Absolutely. And you mentioned something about decaf. And I think a lot of us have really shied away from decaf and in part because decaf tends to be terrible. And I think also in part because it's sort of fun to say things like that before decaf, the first cups of coffee of decaf were made by soaking beans and benzene. And it doesn't take an analytical chemist to tell you that's probably not a great way to make a healthy drink or one that tastes particularly good. But there are a lot of really good mechanisms. So there's something called the Swiss Water Method that's come up in the last ten, maybe a little bit longer years. That makes a very respectable cup of coffee and a method that's more new to me. It's called the sugar cane method. And instead of using water or CO2 or benzene, it uses ethylene glycol. But it's ethylene glycol that's delivered or derived from sugar cane. And the nobody wants to say ethylene glycol coffee. So they say sugar cane coffee, and that decaf is really good. So I've started in the afternoons, I've shifted over to parts of this sugar cane method to decaf, and I think it's a good cup of coffee.

BRIAN GOLDMAN: Now I want to talk about coffee and exercise because I, I tend to work out in the morning. I do a morning run as early as 5 or 5:30 in the morning. And I've heard that coffee can make an early morning run go better. So what do we know about that?

THOMAS MERRITT: So we don't that doesn't make you feel more awake during that runs. I'm traditionally a rower and so we're also up at the crack of dawn and out there with a cup of coffee on the way to the boats. So caffeine is is a list of a list of a series of drugs that are actually approved for international competition. So we're not when we look at high performance athletes, we're not saying you can or cannot have caffeine. We do know there are a series of studies that caffeine definitely impacts athletic performance. Like every other aspect of caffeine, it impacts different people differently. There's studies that are looking at power. There are studies that are looking at strength of studies that are looking at endurance. And there is a lot of variation in how individuals respond to that. So there's some indication that it can improve power athletics. There's some indication that it can improve long distance endurance athletics. It really depends, again, on the athlete. How you respond to that. So at one point when I was doing long distance runs in the morning or longer term rows in the morning, I was using gels as a good source of calories to keep me going. And I found that the caffeinated gels really worked for me as a way to wake me up and keep me going through that run. And again, if you're not drinking a lot of coffee, if you're not consuming a lot of caffeine, I would not recommend you bring it into your athletic performance because it's going to be a big jolt of the system or you bring it in more gently. I mean, some of the caffeine gels are pretty high.

BRIAN GOLDMAN: What are some of those underlying diseases, these conditions that would make you say, you know what, think twice before drinking coffee or having any caffeine in any other beverage?

THOMAS MERRITT: I think one of them there are people who are really sensitive to caffeine and it is a very small percentage, but it's something that we need to be aware of and conscious of. And then addition to that, the things that you've brought up before, like, you know, whether you've got high blood pressure, whether you have things like an irregular heartbeat, those are things that will definitely play into it. There's certainly evidence that's come out from some recent studies that have shown the higher your caffeine intake, the more likely you are to progress through different stages of kidney failure. But that seems to be only if there's an underlying pathology of high blood pressure, too. There's already this tie between blood pressure and kidney disease. If you bring into that a higher amount of caffeine and you sort of accelerate the pace through those diseases.

BRIAN GOLDMAN: We've talked about the relationship between caffeine and sleep, but can you say more about how it you know, does it have any impact on your sleep wake cycles?

THOMAS MERRITT: It absolutely does. And that's why we drink out of caffeine in the morning, is that caffeine helps us break that sleep cycle and move into a wake cycle. That said, we've known that there are issues with caffeine consumption and a good night's sleep for well over a hundred years. So the earliest study that I've got on my computer is from either 1900 or 1908, and it's a scientific study looking at the effects of caffeine through coffee on sleep patterns. For most of us, having a few cups of coffee in the morning doesn't impact our ability to get a good night's rest later in the day. For some people, it does. For many people, having a cup of coffee later in the day can impact that. And there are other things that come into it. If you were in a really stressful time of your life, that addition of stress and caffeine may mean that an afternoon cup of coffee is not a great idea. My first espresso was in Portugal in Lisbon, my first international city. I was 20 years old and I had a dinner, an amazing dinner and finished it with an espresso. And my world changed. This was this was phenomenal, this espresso thing. It was 10:00 at night. I went back to my hotel room and slept like a baby. But I was 20 and not under a lot of stress whatsoever. You know, you start to tie in things like I'm now 54 and I'm under a different kind of stress pattern than I was at 20. I probably won't have as many late night espressos.

BRIAN GOLDMAN: You remember when you had your first espresso?

THOMAS MERRITT: I do. It's a great thing. I didn't actually start drinking coffee until I was in my third year of university. I now spend a lot of time talking about coffee, and I could tell you where I was sitting. The table. I had roast cuttlefish for dinner. I had a nata, which is an egg custard dessert. And I had an espresso and it changed my life.

BRIAN GOLDMAN: Well, since we're we're into confessions right now, I can tell you that I remember making percolated coffee for my mother when I was ten years old. And the smell of that caffeine coming out of that Pyrex percolator. That to me, that's coffee. And I can remember where I was. I can just picture myself in our family's kitchen and I can tell you those are those days when I fast at the end of that fast, the smell of caffeine is just glorious.

THOMAS MERRITT: So, Brian, I have my dad's camp percolator. And when he died a couple of summers ago, one of the things I did was stand in my what was now my mom's kitchen. And I made up a pot of coffee with Dad's percolator.

BRIAN GOLDMAN: Yeah. Bet it brought back a lot of memories.

THOMAS MERRITT: Not of good coffee. But it brought back a lot of memories.

BRIAN GOLDMAN: If somebody is reevaluating their relationship to coffee or to caffeine, what's your advice to them?

THOMAS MERRITT: Yeah, I think that my advice to them is make a really good cup of decaf. If you need to cut back on caffine, have a couple of cups of coffee instead of a couple of pots of coffee and maybe mix in some decaf with that as well. So one of the things that I've done, I was drinking a lot of espressos, which are low volume. Per unit volume, there's less caffeine in it, but you drink a I tend to drink a lot of espressos and I've just gone to the pour over, as we were talking before, a nice cup of coffee. It takes me a little bit longer to go through. I've had this conversation with a couple of scientists from around the world, and one of the interesting aspects sort of twist to the conversation was when we talk about coffee consumption in North America, we're not just talking about caffeine. There's a lot of sugar and dairy, a lot of fat, a lot of calories that go into those. Right? So that's a very different conversation than how many cups of coffee you're having. If you're having a double double or triple triple, if you're putting a lot of sugar, a lot of milk, a lot of cream into the coffee. That's a different conversation than if you're having a coffee black. And so something to be really conscious of as you're sipping on those cups of cups of coffee is sort of how many collateral calories are you bringing in because of the way you're doctoring up that coffee?

BRIAN GOLDMAN: That's a great additional piece of advice. Thomas Merritt, you are a an amazing fund of knowledge about one of. For me, one of the great pleasures in life. And I want to thank you for coming on The Dose to talk about a dose of caffeine.

THOMAS MERRITT: Brian Thank you for having me. It's been a wonderful conversation.

BRIAN GOLDMAN: Thomas Merritt is a geneticist and professor in the School of Natural Sciences at Laurentian University in Sudbury. Here's your dose of smart advice. Coffee contains a mixture of many chemicals, but caffeine is the one we know the most about. Coffee wakes you up by binding to adenosine receptors inside the body, which in turn interrupts your sleep. The impact of the caffeine you consume depends on the dose. 50 to 300 milligrams of caffeine may lead to increased alertness, concentration and energy. Higher doses can lead to anxiety, restlessness, increased heart rate and trouble sleeping. Those are generalizations. The dose of caffeine per cup may vary and different people respond to the same dose of caffeine in different ways. Caffeine consumed within 10 to 15 minutes of exercising may improve your physical performance and cognitive function, but too much caffeine can worsen things by causing nervousness and insomnia. There's not enough evidence to state conclusively that caffeine affects your health one way or another. We can say that having coffee does not appear to increase the risk of cardiovascular diseases and cancers. Still, if you have hard to control blood pressure, you probably want to moderate your caffeine intake. Since caffeine increases the risk of miscarriage and low birth weight, pregnant women should consume less than 200 milligrams of caffeine per day. That's around two cups of coffee. Keep in mind that coffee acts like a pharmaceutical drug. If you're cautious about the medications you take, then exercise some caution when it comes to caffeine. Try switching to decaf and see if it makes you feel better. Tea contains between 1/10 to 1/100 the dose of caffeine found in coffee. So it's yet another substitute to try. If you have topics you'd like discussed or questions answered. Our e-mail address is the dose at cbc.ca. If you liked this episode, please give us a rating and review wherever you listen. This edition of the Dose was produced by Isabelle Gallant. Our senior producer is Colleen Ross. The dose wanted to be better informed about your health. If you're looking for medical advice, see your health care provider. I'm Dr. Brian Goldman. Until your next dose.

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How does drinking coffee affect my health?- Transcript

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