Episode Transcript

Welcome to Health Matters. Your weekly dose of the latest in health and wellness from NewYork-Presbyterian. I’m Faith Salie.

If you’re like me, the day doesn’t officially start until I’ve had my morning coffee. Whether it’s from coffee, tea, or soda, roughly 80% of U.S. adults consume caffeine every day. 

So what are the health-related pros and cons of caffeine consumption? How much is healthy to drink? And is it true that coffee drinkers live longer?

This week, I’m joined by Weill Cornell endocrinologist Dr. Rekha Kumar to help answer questions about this ubiquitous stimulant so many of us rely on.

Faith Salie: Dr. Rekha Kumar, thank you so much for being here.

Dr. Kumar: Thank you for having me.

Faith Salie: So many of us are used to waking up and having a cup — or more — of coffee. How does caffeine affect our bodies? What’s it doing that is so magical inside us in the morning?

Dr. Kumar: Yeah, so caffeine is a stimulant. We have receptors in the brain that sense caffeine and make us feel alert and awake and energized.

So most studies look at the consumption of like 50 milligrams to 300 milligrams of caffeine a day, which seems to be the zone that is considered healthy. And when we talk about the health benefits of caffeine, we’re usually talking in that range. 

So, even pregnant women are told that up to 200 milligrams of caffeine a day can be safe in pregnancy.

So that range of 50 milligrams to 300 milligrams is pretty wide, but it’s the range that we’re talking about when we’re talking about caffeine and health. Beyond that, we start to see negative effects, people feeling too hyper, heart rate going up.

Faith Salie: Not being able to sleep when they want to. 

Dr. Kumar: Absolutely.

Faith Salie: 200 milligrams a day would be how many cups of coffee?

Dr. Kumar: About two cups.

Faith Salie: So other than helping us get through our busy days and giving us some mental clarity, especially in the mornings, are there benefits of coffee consumption? Because I feel like coffee makes the headlines a lot that it’s like, it helps us live longer.

Dr. Kumar: Yeah, so there’s a lot of association with caffeine and improved health outcomes, but we don’t yet know causation. So coffee drinkers have less type 2 diabetes. Interestingly, despite the increase in blood pressure and heart rate when you consume caffeine, coffee drinkers have less coronary artery disease. Caffeine drinkers have less neurodegenerative diseases like Parkinson’s and dementia. So is there something else about these people that makes them healthier and they happen to consume coffee?

Faith Salie: Do you think it matters whether it’s one cup versus six cups a day to get the health benefits? Like, wow, if this makes me live longer, should I have three more iced teas? How much is too much?

Dr. Kumar: It is interesting. There have been studies that don’t really have an upper limit, and I think in, in an isolated study, perhaps we can find that, but I would imagine that at some point it negatively impacts you if you’re trying to consume the caffeine just to live longer.

Faith Salie: Haven’t there are also been some studies that show that even decaf coffee drinkers enjoy beneficial effects? So, it’s something perhaps in the coffee and not in the caffeine?

Dr. Kumar: Exactly. Yeah, something perhaps in the coffee plant and the coffee bean not necessarily related to caffeine because you’re right, there’s been studies of decaf drinkers who see those benefits as well.

Faith Salie: And there are some studies that seem to point to caffeine helping depression?

Dr. Kumar: Whenever something happens in the brain, whether it’s caffeine hitting a caffeine receptor, or estrogen hitting an estrogen receptor, all of these things have some downstream impact on other brain pathways related to mood or sleep. And so we probably don’t fully understand all the connections, but it has been known that caffeine drinkers actually have less depression.

Faith Salie: So, it sounds like caffeine’s a wonder drug. And I have to ask, what happens when we have too much caffeine? 

Dr. Kumar: Too much caffeine would lead to feeling jittery, agitation, insomnia, an unhealthily high heart rate versus just a transient healthy increase in heart rate. 

I think people need to know their limits and that’s different for everyone. There are people that will say they can’t drink any caffeine at any time of day because it makes them feel too anxious or it impacts their sleep. There’s other people that can have an espresso after a 10 o’clock dinner and go right to bed.

Faith Salie: This always astonishes me, by the way.

Dr. Kumar: Same. We’re all individuals with unique biologies and we have to understand ourselves to know what we can tolerate.

Faith Salie: Do we have an idea of what makes certain individuals more or less sensitive to caffeine? 

Dr. Kumar: It’s probably how we’re genetically wired, and I don’t believe we know exactly the gene that makes one sensitive or less sensitive to caffeine, but I would imagine that if somebody has some particular tendency towards it that their first degree relatives are probably similar. 

Faith Salie: Is there a certain age at which you think it’s okay for maybe like a teenager to have caffeine?

Dr. Kumar: I started drinking coffee when I had to study in college. It was probably because I stayed up too late the night before. But I would think that an 18-year-old’s brain is a safe time to have regular exposure. But that, that’s my opinion. But I think we want children to learn how to focus without, uh, chemicals or substances unless they have attention deficit disorder and need medication.

Faith Salie: It sounds like as a parent and as a doctor, what you want for kids is to learn sleep hygiene, right? 

Dr. Kumar: Absolutely. And there’s other downsides to a young person not sleeping, related to growth and metabolism. So we definitely would want to teach that age group to sleep rather than compensate with caffeine.

Faith Salie: What about energy drinks? Should we avoid them altogether? I know there’s a lot of sugar in them, let alone caffeine.

Dr. Kumar: Yeah, there’s also other chemicals in them. I consider coffee and tea in a separate category than energy drinks – or those really popular drinks these days. I’ve noticed that many of them have taurine in them and other amino acids. I don’t believe we know about the safety of some of these drinks and some of the substances in them. Yes, there’s caffeine in them, but there’s other amino acids that could be stimulating or activating to a person, and children are drinking these. So, I actually would prefer that people drink coffee over an energy drink. It seems that the amount of stimulant in an energy drink is quite high, where people could feel unwell.

Faith Salie: What is your guidance when it comes to caffeine consumption and pregnancy or even fertility – trying to get pregnant?

Dr. Kumar: I think there are mixed messages out there. And again, I think it depends on the individual. The scenarios in which we tell women who are trying to get pregnant or who are pregnant to avoid those things are if we are trying to just eliminate all of the possible variables that could be involved in interfering with someone’s health. 

So with the fertility issue, we just really want to be able to treat someone’s infertility without anything that could interfere as a substance. And perhaps we would say to limit caffeine in that case, because the situation is already mildly more complex than somebody that’s naturally getting pregnant.

And in pregnancy, a lot of people are very sensitive to the increase in blood volume, the increase in heart rate, because your heart has to pump more blood, because you have more fluid. Some people that are very sensitive to that, they feel that their heart is beating harder or faster. I would tell them to avoid caffeine, because it’s going to make that sensation or the perception of that sensation worse.

Generally speaking, I would say that for the average healthy woman, it is safe for them. If the situation is more medically complex, we might ask them to cut back.

Faith Salie:  I remember I cut out caffeine for years and then when I started using it again, I feel like I could harness its power when I really needed it.

Dr. Kumar: That’s absolutely true. And that’s true for many things that have brain receptors the more you hammer those receptors with the substance, they what we call “down regulate” and it requires more of the substance to get the same feeling, so then the reverse of that would be if you want that feeling easily with whatever the substance is, caffeine or anything, then you’d have to retrain your brain to upregulate those receptors, meaning that even if a little bit of the substance is around, you get the downstream benefit.

Faith Salie: What are some recommendations you can offer to individuals who want to regulate their caffeine intake?

Dr. Kumar: If I had to look at the population as a whole, if I had to give blanket advice to everyone, I would say, it’s still not a replacement for water. So I’d want people to hydrate with water and try to get their caffeine intake in in the first half of the day, so they still have a healthy wind down and sleep routine.

Faith Salie: Dr. Rekha Kumar, I raise my mug to you. Thank you. This was, this was both stimulating and comforting conversation.

Dr. Kumar: Thanks so much for having me today.

Our many thanks to Dr. Rekha Kumar.

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