Short-term side effects: jitteriness, anxiety, increased heart rate, and urinary frequency.
Impact on sleep: meta-analysis shows reduction in total sleep time and deep sleep.
Temporary increase in blood pressure for some individuals. No long term increase in hypertension.
Withdrawal symptoms upon cessation of caffeine consumption.
Conclusion and Recommendations
Caffeine is generally safe and offers benefits with minimal long-term harm.
Personalized approach: conduct an "N of 1" study to assess individual response to caffeine.
Join Us Next Time!
Stay tuned for our discussion on nutritional supplements and their role in promoting health and longevity.
Bobby Dubois:
Hi, I'm Dr Bobby Dubois and welcome. To Live Long and Well, a podcast where we will talk about what you can do to live as long as possible and with as much energy and vigor that you wish. Together, we will explore what practical and evidence-supported steps you can take. Come join me on this very important journey and I hope that you feel empowered along the way. I'm a physician, ironman, triathlete and have published several hundred scientific studies. I'm honored to be your guide. Studies. I'm honored to be your guide. Welcome back everyone. We have finished our six pillars to live long and well in the prior episodes, and those six pillars are exercise, sleep, nutrition, mind-body harmony, exposure to heat and cold and social relationships. Now, if you've missed any of the episodes, feel free to get caught up. They're all still available Now.
Bobby Dubois:
Today I would like to talk about something near and dear to many of you listeners our morning coffee, and our episode is entitled Is it a good or bad idea from the standpoint of health? Now, as you know, I like to begin with the take-home messages. So there are several. First, coffee does have some short-term side effects that most all of us understand feeling jittery and it may impact our sleep. But coffee has some pretty well-identified benefits, definitely from an alertness and exercise performance standpoint, but there's some suggestive evidence that we'll talk about related to improvements in liver disease and reduction in risk of dementia. So, third, the good news is that it's a pretty clean drug, meaning there are benefits without major problems. So enjoy your morning coffee. And, as always, I will put links to key references in the show notes. Well, our plan for today has three segments. First, I'd like to provide some background on coffee and tea, its history and how it works, briefly, in your body. Second, we'll explore what the benefits of coffee appear to be based upon what scientific studies have been done in people. And, third part, we'll understand if there are any downsides to coffee. And, of course, we'll end with some next steps and we'll talk once more about the N of 1 studies, so you can tell whether your coffee or tea is having impact on you, either positively or negatively.
Bobby Dubois:
Well, let's begin with some background. Caffeine is the most widely used drug in the world. In the US, about 60 to 70 percent of adults drink coffee every day, and the average in the US is about three cups per day. Now, if you add in tea drinkers and those who drink Coke or Mountain Dew or Dr Pepper. That's a lot of caffeine being ingested by a lot of Americans, and we ingest a lot more caffeine these days than in the past. So some folks may recall, in the 1960s coffee didn't come from a Starbucks or didn't come from fresh beans that you might purchase at the deli counter, but rather coffee came in a can like your Folgers can, and the directions at the time were use one teaspoon per six ounce cup of coffee. So pretty low amount of caffeine. Now let's march forward in time With Starbucks. Today they're recommending on the package that you give not one teaspoon per cup but rather one tablespoon or maybe even one and a half tablespoons per cup. And at Starbucks and elsewhere most drinks are 16 ounces, so not the usual six ounces. That was done in the decades past. So in the old days when someone had a cup of coffee in the morning, it was probably about 50 milligrams of caffeine. Now, if you're a Starbucks regular or you make a strong coffee at home, that's likely to be six-fold higher or 300 milligrams of caffeine. So keep that in mind as we think about the impact of caffeine. There's a lot more that gets into our system now than in decades past.
Bobby Dubois:
Caffeine has a long history. Tea was discovered in China around 1000 BC, so 3000 years ago and monks used it to enhance their meditation, their ability to stay awake for long periods of time, so the impact on the mind was known for a very, very long time. Coffee has a bit of a younger history, and it was discovered so this legend is in Ethiopia, around 850 AD, there was a goat herder again as the legend goes and his goats would be walked around on the hills and wherever, and at one point Kaldi's goats started to jump around like they were crazy, and what he found was wait a second, they're eating a bunch of berries of a particular plant, and of course, that turned out to be the coffee plant, and so why they were jumping around is they got a whole bunch of caffeine. So that's the legend. Whether it's absolutely true or not, I don't know. There were no scientific studies done at the time. Well, we're talking a bit about coffee and tea, but caffeine is also in cocoa beans and kola nuts.
Bobby Dubois:
Let's put some numbers so you have a sense of how much caffeine might be in various things you would drink or ingest. So espresso a shot of espresso is about 60 milligrams of caffeine, and I mentioned earlier that Starbucks may well have over 300 milligrams in a 16-ounce cup of coffee. Black tea typical cup would be 60 to 80 milligrams of caffeine, kind of like what an espresso is. Energy drinks like Red Bull, which were invented back in the 80s and obviously have become very popular since that time, have about 200 to 300 milligrams, or close to what a Starbucks cup of coffee might be. Now people may remember No-Dose and at the time that was like oh my goodness, that's a massive amount of caffeine. Well, it turns out that a No-Dose dose is less actually, than a Starbucks cup of coffee. It's about 200 milligrams. Cola, diet Coke, regular Coke they both have about 30 to 40 milligrams of caffeine.
Bobby Dubois:
Now be aware that even decaf coffee has caffeine. And for some people and we'll get to this a little bit later I'm one of those people I'm hypersensitive to caffeine. I love it, but it affects my body quite a bit. Even a 16-ounce cup of decaf at Starbucks has 25 milligrams of caffeine, or about the same as having a Coke. So if people say oh, I just drink decaf, so it's not a problem for some people, it is something to be aware of. And even chocolate just having a chocolate bar not an espresso bar, but a chocolate bar has 25 milligrams if it's dark chocolate and about 10 milligrams in a serving of a milk chocolate bar. So caffeine is in a lot of different things and it might be good for you to take a stock of how much caffeine you have a day and just add up all the coffee or tea or coke or chocolate you have. This might be a good baseline and we'll come back to this a bit later.
Bobby Dubois:
So what does caffeine do? I don't want to get lost in the biochemistry, so I'll just give you a very tiny taste. So the body has a chemical called adenosine and in the brain it causes us to relax. So as the day progresses, your adenosine levels in the brain go up and up and up and at some point you have so much adenosine in your brain it says I really want to go to sleep. Now, what caffeine does is it blocks the impact of adenosine, so it's blocking that sleepy feeling that your brain is experiencing. So caffeine blocks the adenosine. The adenosine would have made you sleepy, so of course it keeps you more awake and as such it's a stimulant. So caffeine I mentioned earlier is in fact a drug, and it is something that helps wake us up, it keeps us more focused in our brain and it makes us more alert. Now I'm not going to be able to answer this question because nobody knows the answer to this question, but there's a complicating factor to all of these studies and all of our understanding of the field. So I've been talking about caffeine as if it was the agent that's causing all the benefits and harms.
Bobby Dubois:
Well, is it the caffeine or is it the coffee? So there's been a lot of studies on coffee. We assume that it wasn't. What else is in the coffee? It's, in fact, the caffeine. And is it the caffeine in the tea or is it something else? People talk about antioxidants and other things, so just keep in mind that we haven't fully disentangled. Is it the coffee? Is it the caffeine? Is it some combination of the two? There are very, very few studies that took people and gave some regular coffee and some decaf coffee and compared the differences. That, of course, would help us understand whether in fact, it's the caffeine or it's the other stuff in coffee, but there's very, very few studies like that.
Bobby Dubois:
Also, be aware that each of us may respond differently to caffeine in coffee. There's a lot of people that tell me, bobby, I can have an espresso for my dessert after dinner and it doesn't bother me at all. Well, that's absolutely true for some people. I, as I alluded to earlier, am someone that if I have a full cup of coffee at seven in the morning, by the time I want to go to bed at nine or 9.30 in the evening. I'm still pretty wired from the coffee. My body really, really, really, is sensitive. Now, some of you might have done 23andMe or one of the other assessments, and there is, in fact, a gene that codes for whether you metabolize caffeine quickly or not, and so some of this sensitivity to coffee and caffeine is genetic and that's something that you should also keep in mind. And if you happen to have done a 23andMe test, go back and look at the results. It might tell you All right, so that's what caffeine is, that's where it came from.
Bobby Dubois:
So now let's figure out what are the positive effects of caffeine and then, of course, we're going to talk about the negative effects. So I already alluded to, and most anybody who drinks coffee or tea or Coke or anything else, knows that caffeine tends to wake you up, make you more alert, more focused People find it's helpful if they want to concentrate, to have that, and I mentioned earlier that the monks in China used it as part of meditation and being awake. But there are some other things that have been measured in scientific studies and, as we've talked about a number of times, my interest in scientific studies is not what happens in a laboratory setting with biochemistry and blood. I want to know what happens in real people. So there's been some randomized clinical trials. Now some of these have been pretty small numbers of people, so we can't say we know the full answer. But they gave people caffeine and then for cyclists or sprinters, they asked well, how much power do they generate, and does the caffeine increase that? And the answer is it did about 5% to 8% improvement in the power output. So that's something that's quite interesting and something you might want to experiment with in your own daily exercise.
Bobby Dubois:
Caffeine also reduces our perception of pain, and some of you may know that in certain analgesics for migraine and things, caffeine is included. Now it's a vasoconstrictor and it may help in that regard, but I believe that it also reduces our awareness of pain, or at least the bothersome part of it. I know when I'm doing athletic events and I'm getting very tired and feeling sore all over. If I have some caffeine it certainly wakes me up, but it also reduces my sense of discomfort from the exercise. And it's also been shown that for asthmatics caffeine can improve lung function. And that's not a big surprise because the chemical agent of caffeine is not that different from the types of inhalers many people use when they're feeling a little wheezy as an asthmatic. So the benefits I've just mentioned are pretty darn definitive and I think most people would agree. The literature shows that. Now the following benefits I would put in the suggestive category exciting category, interesting category, but not definitive.
Bobby Dubois:
There is evidence for all of these but it's not highly rigorous large clinical trials, it's mostly from observational studies. So one study called the Nurses' Health Study found that regular coffee drinkers had a reduced risk of stroke in women. In another study that looked at about 1,400 people and they followed these people for over 20 years and they compared people who drank about three to five cups a day versus those that drank much less or not at all. And the coffee drinkers the higher level coffee drinkers had a 65% decreased risk of dementia. Also, that similar number of cups per day was also tested for decaf. Remember I mentioned that there are very few studies that compared what happens with regular coffee versus decaf and what they found in this study is that decaf did not protect against the cognitive decline, whereas the people who drank the regular coffee did.
Bobby Dubois:
There's also data in patients with hepatitis that coffee drinking reduces the damage to the liver and may have an impact on the development of cirrhosis, which is sort of the end stage deterioration of the liver or even liver cancer. And finally and I can sort of relate to this anecdotally, but there's actually studies on this coffee or caffeine might temporarily reduce our appetite. I know when I have a cup of coffee in the morning, I'm not very hungry for breakfast. And if I'm trying to sort of skip a meal and do intermittent fasting as a way to sort of keep my calories under control, having that cup of regular coffee can be helpful. And again, there are studies to support this. And all of these studies that I mentioned will be in the show notes, so do take a look if you're interested. So those are the benefits, some that we feel pretty strong are definitive and some that are uncertain, promising and we hope will turn out to be true.
Bobby Dubois:
So what are the downsides of caffeine, which is the next part of our podcast? Well, most everybody knows that when you drink coffee, or if you drink too much of it, it can make you jittery, can make people's hands shake, some people get anxious, they might have a rapid heartbeat and they might end up going to the toilet more and urinating more. There were concerns, especially in people who had heart attacks, that having caffeine might cause heart arrhythmias, and it appears that's not the case. So that's a downside that we were worried about, but doesn't seem to be a real concern.
Bobby Dubois:
One area where the data is pretty clear, at least for some people, is that caffeine has an impact on our sleep, and I often talk about a meta-analysis, which is a study of many other studies. So in this meta-analysis, which is an analysis of 24 different randomized trials, and then they averaged the results across all of those, what they found is people who had coffee relatively close to when they went to sleep had a 45-minute reduction in the number of minutes of sleep for each night. Now this is really important because we've talked before about how we often don't get enough sleep and the magic number is around seven hours, and so if you were roughly getting about the seven hours, and now you had the caffeine on board in your system and it affected you by 45 minutes. That's a big deal. We've often talked about how one of the ways to be more convinced that a study findings are real is what's called a dose-response relationship, meaning that the more coffee, the more deterioration in sleep, and that has been observed. I mentioned the 45 minutes of overall sleep reduction and there was a reduction of about 11 minutes of deep sleep. Now, to put this in context, people often only get 30, 60, or 90 minutes of deep sleep, so 11 minutes is significant. In this analysis, they didn't see any impact on REM sleep. In this analysis, they didn't see any impact on REM sleep.
Bobby Dubois:
Let's move on to the next, and that is blood pressure. Will caffeine affect your blood pressure? And the answer is yes. It will temporarily raise some people's blood pressure Not everybody's, but some people. Blood pressure Not everybody's, but some people. But there was a long-term study asking the question of 1,400 adults over the course of 10 years and they asked them whether they were coffee drinkers or not and how much they drank, and what they found at the end of 10 years is the likelihood of high blood pressure was no different between the coffee drinkers and the non-coffee drinkers, so it does not appear to cause hypertension. Again, it might temporarily, on a given day, increase it, but it doesn't appear to cause a long-term impact.
Bobby Dubois:
People know, when you don't drink coffee, if you're a regular coffee drinker and you skip a few days of coffee, you might have withdrawal symptoms, which could be a headache or fatigue or difficulty concentrating. So, to sum up the downsides, there really are no long-term bad effects. It's what we call a pretty clean drug, meaning you get benefits but not too many harms, or at least the harms are temporary and they're pretty obvious. Well, we're about to finish up, but I want to then ask the question so what should listeners do with this information? Well, for many, the punchline is all they care about Enjoy your morning coffee or tea. It appears to be just safe. And, yes, it has some side effects, but most people will be aware of them and they'll be temporary.
Bobby Dubois:
We've talked in the past about an N of 1 study. So all the studies I've talked about today and often in the past have looked at a large group of people. Some were coffee drinkers, some were not, some were heavy coffee drinkers, some were not, and we are looking at the average experience. But, as I mentioned, genetics play a role here and personal response to caffeine varies a lot. So the N of 1 study is to ask the question well, in you, uniquely, you personalized medicine you.
Bobby Dubois:
Does coffee or caffeine affect you and in ways that you might be concerned about? So what do we do? Well, in our standard N of 1 approach, we take a baseline assessment. Now let's say it's sleep you're concerned about. So you might do a baseline assessment of your sleeping. And are you sleeping a lot of hours or not? What's the quality of that sleep? Then the next step is to ask how much caffeine you're consuming in a day. Now, nominally, up to about 400 milligrams is a safe amount, but you should take a look and see for yourself how much you're having, then change something, perhaps reduce how much you drink, or when you drink it relative to going to sleep, and then, a week or so later, reassess your sleep. Did it make a change? Now you can do the exact same approach with exercise and see if it helps to have coffee before you exercise, and this way you will know what caffeine does for you and whether you want to continue having it or not, whether it's affecting your sleep or not, and whether it might improve your ability to work out or not. So that's the end of our coffee discussion.
Bobby Dubois:
Next time we're going to explore the often controversial topic of nutritional supplements. Now most Americans take them and we'll talk in specific about what the most common ones, but my understanding of the evidence is that, by and large, nutritional supplements don't really matter. Maybe a multivitamin day is a good idea, but all the other things that often people consider the evidence is not very strong. So join me again as we continue our journey to live long and well. Thanks so much for listening to Live Long and Well with Dr Bobby. If you want to continue this journey or want to receive my newsletter on practical and scientific ways to improve your health and longevity, please visit me at drbobbylivelongandwellcom. That's drbobbylivelongandwellcom. That's Dr DR Bobby. Live long and wellcom.