What's the deal with creatine?

13:34Perry Wilson:I mean, I think the first thing to just tell people, like literally creatine is an amino acid. It is an amino acid that you consume in food.

13:42Emily Oster:It's a derivative of an amino acid. I only say because we did the peptide episode.

13:49Perry Wilson:I'll say, doctor, I'm a real die. I went to medical school. Blah, blah, blah. No, go ahead, please.

13:56Emily Oster:Because we said there's 22 amino acids that people use and creatine is not one of them. It's a derivative of an amino acid. But yes, by all means, continue.

14:05Perry Wilson:You consume creatine in food, primarily in meat and seafood, and you store it in your muscles, and it is helpful for making the muscles work, particularly in an anaerobic way. I think the core thing that's relevant for this question of supplementation is that your muscles can generally store more creatine than most people can get in meat and most people can get through their food. So when people supplement with creatine, it like ramps up the stores of creatine in their muscles. And in principle, that can then help you when you are exercising in particular ways at very high levels. That's kind of the core thing.

14:46Perry Wilson:So do you exercise to failure on a frequent basis, Perry? No, but I've done it. What does it mean to exercise to failure?

14:56Emily Oster:Have you ever exercised? Have you ever done an exercise?

14:58Perry Wilson:I feel like I exercise to failure every like three days, but I don't, I'm not sure that I know what that means. Okay.

15:06Emily Oster:Exercising to failure literally means that you're doing an exercise, let's say pushups and you just continue to do pushups and do pushups and do pushups until your muscles give out. They literally fail. And I think it might be worthwhile to talk about physiologically, like what is happening there, because that might be the best way to understand how creatine works. So if you do pushups and you keep going and you don't do like, I'm going to do 20, I'm going to do 30, I'm going to do 50. You just keep going, going, going until your arms, what will happen? Have a pillow under your face because your arms will literally stop working and your face will smash into the ground.

15:42Emily Oster:And there's nothing you can do about this. This has happened to me. The bodybuilders will do these types of exercises to failure. What's happening in the muscle when your muscle is contracting is the muscle is using energy. And the energy currency of all the cells in your body is ATP. Probably heard us mention that before. But think of it as like cash, spending cash in terms of what cells can use for energy. There's a problem. And that's that cells can't store very much ATP. It's unstable. It's hard to keep it in its activated form. So it's like they've got some cash in their pocket, but it's not enough to go on a huge spending spree.

16:20Emily Oster:That's sort of how I think about ATP. For most cells, that's not a problem because they use a little energy to like whatever they're doing. Your gut cell uses some energy to absorb some glucose or whatever, and then it's done for a while and it chills out and builds up more ATP. No issues. But there are some cells in your body that use energy like a lot in over a period of time. and muscle is definitely the biggest one. And that includes your heart muscle, but your skeletal muscles as well. If all they had to use for that energy was ATP, then after about three seconds of muscle contraction, all the ATP in a muscle cell is gone and the muscle fails.

16:58Emily Oster:And that means it just goes slack and your face smashes forward into the pillow that you put under you when you're doing pushups. That's not compatible with moving around or lifting up anything. You can't have only two seconds of muscle contraction. So what creatine is, is a store for phosphates that can regenerate ATP. So remember, you can only have so much cash in your wallet. You can't have too much ATP in a cell, but you can have lots of creatine. That's your bank account, more or less. And so as your ATP is being used up, creatine in the form of creatine phosphate is regenerating ATP. So you're taking cash out of that.

17:38Perry Wilson:It's the ATM. It's your cells as an ATM.

17:42Emily Oster:Exactly, exactly. And as you pointed out, most of our muscle cells, based on a typical Western diet, actually can hold more creatine than they have. And what that means is that if you build up your store of creatine by creatine supplementation, in theory, you have this extra amount in your ATP bank account that you can extract upon. So it's a little different. from people often say creatine is like energy for your muscle. It's more like the presence of creatine allows your muscle to bank energy when it's not being used so that it can pull it out again when it is being used. It's almost acts more like a battery or like a rechargeable battery, but you still have to do the recharging.

18:26Emily Oster:Creatine does not have calories in it, creatine monohydrate, right? Like, so it's not energetic itself, but it's a place to store energy in your muscles. There's one other set of cells that do tend to be active a lot and use a lot of ATP. Which is your brain. Right. That's up in your brain. So that's why you see a lot of muscle and brain talk for creatine. Yeah.

18:47Perry Wilson:All right. So let's start with the muscle talk and then move to the brain talk because the muscle talk is in some ways a much easier conversation. Totally. So the thing we know, I think with incredibly high certainty, is that if you are doing a lot of bodybuilding related exercise, creatine supplementation can improve your performance. We have hundreds and hundreds of randomized controlled trials of people doing bodybuilding activities, which will show that creatine supplementation on average increases the time to failure. So allows you to do more of those pushups before you smash your face in the pillow.

19:31Perry Wilson:And this has been used by bodybuilders for decades. I mean, this is like a very standard bodybuilder activity.

19:41Emily Oster:Talk to me for a second, because this will come up again. You said randomized controlled trials. Why, in a study that's looking at something like muscle strength, muscle performance, whatever your metric is, why is a control, randomization and control, like a placebo control so important? Because there's plenty of studies that aren't placebo controlled, particularly when we look at the brain. So why does that matter when you're talking about things like muscle strength and function?

20:06Perry Wilson:Yeah, I mean, I think the core thing is that actually a lot of your muscle strength and function is what you think you can do, right? So if you sort of, in general, like let's back up. In general, we like randomized control trials because we have treat people the same and the only thing that's different is what thing we're giving them. In this case, it's actually really important that not only are we choosing at random who's getting the creatine, but that we are also doing something to the other group that makes them think they're getting the creatine or that they might be getting the creatine, right?

20:40Perry Wilson:Because if I tell you, hey, I gave you this like amazing substance that's going to make you be able to do more pushups, you will be able to do more pushups. Even if what I have given you is literally like a flower or something, or just like nothing, I guess flower would be helpful. Like if I just give you nothing and I tell you this helps you do pushups, you will do more pushups. Like that's how our brain is, which is cool.

21:00Emily Oster:Yeah, it's kind of amazing. It's like Dumbo with the feather. Remember he has the feather that can make him fly. And then at the end he loses the feather, but it turns out he could fly all along.

21:11Perry Wilson:Remember? Right, I do remember. I do remember. And that movie makes me sad and so sorry. Thank you for please never bring it up again. And so, yeah, so the placebo effect is like one of our best. It's like one of our best effects. It really works very well. But if you want to evaluate the impact of creatine on any of these things, you need to like sort of turn off the placebo effect by having a true double blind, randomized placebo controlled trial in which people don't know what group they're in. And in the case of these bodybuilders, we have that because it's, of course, it's easy. this we can come back to this in other settings but it's really easy to experiment on athletes like that's a great population for experimentation oh my gosh they love to first of all they love to be they love you tell some athlete like i had a randomized control trial of something which might improve your performance it's like where do i sign up right and this and the second thing is often what you're looking at in the outcomes is really easy to define and is short term right so you can run one of these studies in like like a few days you give some people creatine you give them some people and some other powder.

22:16Perry Wilson:You ask them to do a bunch of pushups with a pillow under their face and like, then that's it. That's your, that's your paper. And that's so much easier than like, I'm going to treat this and I'm going to see whether you develop dementia like 50 years from now. That's just a much harder thing to study.

22:30Emily Oster:Yeah. And that's one of the reasons we have so many studies and you'll always hear almost every influencer I looked at talking about creatine opened with like, it's the most studied supplement in the history of mankind, which I couldn't find any reference for. Like I'm not entirely, I think vitamin C and like, I think I'm not sure if that's true, but it has been studied a lot. I'll give them that.

22:49Perry Wilson:As of 2003, in some review, there are like five, there's like a review with 500 papers and that's like 25 years ago. So I, and this has only become more pop. So I think it's a very highly studied. I'm not sure we don't count paper. That's not like the, that's not a metric, an official metric, how many papers have been written on something. But anyway.

23:06Emily Oster:Yeah, no, definitely not the best metric, but let's put some, let's put some numbers to it. So we could pick from a lot of papers. Sometimes the best thing to do when there are a lot of papers, and especially a lot of randomized controlled trials, is to look at a meta-analysis, which is a single paper that combines the results from multiple papers to kind of give you an average. It's sort of the idea that every paper is going to have little errors going one way or another, and you kind of average them out to get an estimate that's more true. And so one that caught my eye because probably it speaks to my age is a recent meta-analysis appearing in the journal, Nutrients, looking at creatine supplementation with resistance training on muscle strength gains in adults under 50 years of age.

23:53Emily Oster:So there's quite a lot of research in older adults for muscle function and falls and things like that, which is interesting. But, you know, I'm not quite there yet. And I'm more interested, like, for me personally, I want to go to the gym and, like, look a little better and feel a little stronger. And I'm otherwise healthy. And so I was very curious to see, like, okay, what can I expect from creatine? So this study compared creatine supplementation and resistance training to placebo plus resistance training. and they looked at upper and lower body strength. And basically they found that the people randomized to creatine could lift an extra 4.4 kilograms on the bench.

24:34Emily Oster:That's what, like about 10 extra pounds? 10 pounds, yeah. Yeah, 10 pounds on the bench press and 13 kilograms on the leg press. So, you know, maybe 25, 30 pounds on the leg press. That's not nothing. I mean, you're not old all of a sudden, but that's real. What do you think?

24:52Perry Wilson:Yeah. I mean, I think that seems real. And I also wouldn't, there's two things I would say about that. So one is I would not dismiss the old people evidence. I actually think that's the other piece of evidence here, even though, you know, you're not, we're not yet older adults, but actually the other really strong piece of evidence around creatine is the benefits on falls and on mobility for older, for older adults. But in both those populations and in the, like the setting you're talking about, it's actually very important this be combined with resistance training. So just taking a bunch of creatine and doing nothing will not matter.

25:26Perry Wilson:The thing that creatine is helping you do is helping your muscles exercise closer to failure, which allows your muscles to break down more and then allows them to build back more. So we want to be like very clear on this, even on the well-established muscle stuff, that it is not just taking the creatine. It is taking the creatine and doing some strength training at the same time that is really important.

25:50Emily Oster:And honestly, not only doing whatever strength training you normally do, the benefit derives from the fact that you should be able to do slightly more. We don't want anyone to hurt themselves. We want you to ramp up slowly. And if you can afford a personal trainer to even work with you to get there, that's amazing. I certainly can't. You do have to be careful. But right. Creatine isn't magic. It allows you to do a little more work, but you've got to do the more work if you want to see the improvement. All right.

26:21Perry Wilson:So that's on muscles. I want, because it's my deep passion to say very briefly, if you are an endurance athlete, so this is like, there's also an active discussion around people who do sports that are not like bodybuilding sports. And the evidence for creatine supplementation in like running and cycling is less compelling for reasons that I think make sense with the biology. So, you know, you asked about sort of exercising to failure. It is rare, even in, you know, pretty intense, like even in like long distance running to exercise to the kind of failure you have described. It does happen. You will see people at the end of a marathon, like sort of unable to like control their body and like just sort of like crawling across the finish line.

27:09Perry Wilson:Like, but that's not common. Uh, that's not common. And so the kind of thing that creatine would help with is like, just, it's less obvious. It'll be helpful there. I will say a lot of endurance athletes do take low levels of creatine because like, why the hell not? Um, just in case it might help because we're, we're insane, but the evidence isn't as, it isn't as strong.

27:30Emily Oster:I'm so tempted to ask you if you take it, but we're going to wait until it's not your best. Oh, you don't. Okay.

27:37Perry Wilson:100%. Because someone once said that it might make me faster. Have we learned nothing about my psychology? Someone suggested.

27:46Emily Oster:All you need to do is say you can run faster or longer and Emily will do - A little bit.

27:50Perry Wilson:A little bit faster or longer. I'll do it. Absolutely.

27:54Emily Oster:Yes. So let's, while we're sticking on effects, I mean, we've got, Of course, we have to talk about how you get creatine and stuff, but maybe let's go on to the brain because I think the data for muscle is great, but what I'm hearing from a lot of people, and especially online, even that first influencer is talking about creatine for Alzheimer's disease and things like that. We'll get to general brain effects for a second, but I'd like to play a quote from an influencer for you. You're not going to be as surprised at this as I was. There is a supplement that reversed memory loss in people with Alzheimer's disease in a new double-blind placebo-controlled trial right here in the United States, and very few doctors are talking about it.

28:41If you are new to my channel, hi, my name is Robert Love. I'm a neuroscientist and I have a medical clinic in Florida where we are reversing Alzheimer's in our patients. This study was released June 4th or June 5th of 2025. five, Kansas Medical School did a double blind, placebo controlled trial in adults with Alzheimer's disease. Half the adults got creatine, half the adults got a placebo. Here's what they found. The adults who took creatine actually improved their memory in this study. Now, the thing is, they give them a very large dose of creatine. The dose they gave them was 20 grams a day.

29:15Most people are taking three to five grams a day, maybe 10 grams a day. These people took 20 grams a day. There were no serious side effects. in fact really no side effects at all of taking 20 grams a day so the people did not feel bad and they improve their memory now creatine is one of the most studied uh supplements on on the planet lots of research specifically on athletes for muscle health women this is especially important for you women you make less creatine than men do creatine is evolved in in the in the process of energy basically it helps make atp and so think about it when you make more atp uh the creatine And some of it can get into the brain and that can help your brain make more energy and that can improve brain function.

29:56Emily Oster:So, yeah, Emily, I was doing the research for this this episode and I was looking into the literature about creatine in the brain and I put together all my notes. But then, of course, I went to the influencers. I wanted to see what people were saying. And here's someone saying like, there's a, you heard the words, randomized placebo controlled trial of creatine for Alzheimer's disease. And it showed that it fixed their memory problems. And I was like, huh, how did I miss that? Like, that's a big deal. How did I miss that trial? And this is a, this influencer is like a doctor. They have a clinic down in Florida, like it's always Florida, but you know, whatever.

30:40Emily Oster:So I did a little bit of sleuthing and I actually found the study that this influencer was talking about from the context clues, the number of patients, the university was sent out of, et cetera. I found it. And it's not a randomized trial. It's, there's no randomization. It's not placebo controlled. It's just 20 people with Alzheimer's who got some memory testing and then went on creatine and then got some more memory testing and there was some modest improvement in memory from before and after. But remember, we've already talked about like the importance of randomization and placebo controls.

31:13Emily Oster:So I know how you'll feel about this, but like, I'm still having trouble with the influencer world. Like you can just say anything like, is there, are there no rules?

31:22Perry Wilson:What I think is interesting about this one, of course, yes, there are no, there are no rules. But what was interesting about this was it's so specific. Like often in these influencer things, You'll hear, you know, there's a new exciting study that says that creatine works for Alzheimer's. But to be sort of specifically wrong is actually quite dangerous because, of course, like anybody who found this study would be like, oh, well, it's actually not a double-blind placebo-controlled randomized trial. It's not a randomized trial of any sort. It's just like a study of some people. So I think it's dangerous to be too specific with your lies in the Internet.

31:55Perry Wilson:But at any rate, there is not a double-blend placebo-controlled randomized trial of patients with Alzheimer's that shows effects of creatine, full stop. There is not.

32:06Emily Oster:There's not. And while we're on the subject of the neurodegenerative diseases, this is, again, a place for the reasons we talked about. Because brain cells do use ATP at a rate that is faster than your typical cells, it makes sense to test these things. I'm so glad that people are evaluating, especially a relatively benign supplement like creatine for degenerative neurologic diseases. But to give you the data on this, there's a large randomized trial, 1 ,700 people with early Parkinson's disease. They were all within five years of diagnosis. This is coming from the Journal of the American Medical Association in 2015.

32:47Emily Oster:They were given creatine monohydrate 10 grams a day for a minimum of five years. This is a placebo-controlled randomized trial. I mean, what an amazing study, right? Yeah. And it was actually -

32:58Perry Wilson:I mean, actually to run a study like that is extraordinary. Extraordinary. Really, really impressive.

33:04Emily Oster:Yeah. Kudos to the authors. The study was stopped early for futility. So when we run trials, especially trials that are expensive, like this one would have been and that go on for a long time, we'll have an independent statistical board that looks at the data at some specified time points and says, is it possible that if you continue this study, you'll see a signal of benefit? Or at this point, based on the data we have, unless every single person who gets creatine does amazingly well, you're not showing benefits, so you might as well stop now. It's no longer ethical to continue this trial. So super impressive, no effect in Parkinson's disease.

33:42Emily Oster:And then there's another relatively large trial in the space, 550 adults with Huntington disease, they were getting creatine monohydrate titrated up to 40 grams a day. We'll talk about the dosing, but that is an incredibly high dose, also placebo controlled and also halted for futility. So not a panacea.

34:05Perry Wilson:I will say on the other side, there is a much smaller meta-analysis from 2018 where they put together a number of small trials, this in the end totals like fewer than 300 people, but looking at just general cognitive performance. And there, you know, maybe they get a little bit of a signal on short term memory. You know, this is not in a in a diagnosed population. The results are pretty weak and they only show up for a small number of outcomes and they mostly show up for vegetarians, which, you know, could be because they don't get enough meat or could be because you're cutting the data enough to find a group where it matters for.

34:49Perry Wilson:I don't really know. So putting all of this together, I would say certainly the evidence for brain impacts is far, far, far, far, far weaker than the evidence for muscle impacts.

35:03Emily Oster:I agree. You know, in terms, one of the issues with the brain, it's like muscle's pretty easy to study? You know, it's like, how much can you bench? Like, that's a very reasonable metric. But like, how well your brain works is really hard. You know, we think about memory. But if you look at detailed neurocognitive testing that happens in a lot of these trials, it's, it's memory, it's attention, it's executive function, it, you know, there's all these sort of components, many of which overlap with each other, some of which we don't fully understand, all of which have scores on scales that are impossible to explain to anyone.

35:38Emily Oster:And it's very hard to say like a global estimate of like it makes your brain better. You're right. If there was one thing that keeps kind of standing out in these smaller trials of, you know, older adults, it's probably memory. I mean, did you did you find that as well?

35:54Perry Wilson:Like if it's short term memory, it's kind of short term memory issues, which which is something a lot of older adults struggle with. And so that sort of comes out most consistently in these trials. It's also a relatively straightforward thing to measure as opposed to, you know, measuring someone's executive function is much harder than measuring their short-term memory, which you more or less do by telling them a bunch of words. And then a little later at the end of the study being like, do you remember what those words were? So there's a series of pretty standard tests for that. So I guess the other thing I would say about this is like there's an interesting link with, you know, mobility and exercise and not falling down and the brain, right?

36:37Perry Wilson:So one, one thing that could be true is like you take creatine and you do some resistance training. And so then you don't fall down and then you, you know, end up interacting more in the world. That's actually really good for your brain. So there's a whole set of interacting things when we talk about the elderly, uh, where anything that improves your ability to do the activities of daily life is likely to improve your brain because your brain is benefiting from doing the activities of daily life.

37:04Emily Oster:Absolutely. So let's talk a little bit about how people get creatine. Okay. So we, let's say that people say this sounds pretty good. I want to bench a little bit more. So all you have to do if you want to get creatine is post an Instagram and say, I like, I like creatine. And apparently it shows up at your house. Why doesn't this work for me? I don't know. No, we're going to work on it. People, Harry needs creatine. Combined, Emily and I have over 500 ,000 Instagram followers. It's so true. It's so true. All right. So creatine, as you pointed out, comes from meat because meat is muscle and animals are just like us and they have creatine in their muscles as well.

37:50Emily Oster:Vegetarians are people who potentially aren't ingesting creatine in that way as much, which is why some of the data restricted to vegetarians looks a little bit better for creatine supplementation. I should say that creatine is not an essential nutrient. So essential nutrients are things that you must ingest or you die, right? Like vitamin C. If you don't, you get scurvy, you die, et cetera. Creatine is synthesized by your body. It's synthesized in the liver and the kidney, but probably not as much to sort of saturate how much your muscles can take. They really can take quite a bit of creatine.

38:23Emily Oster:And as you pointed out, even meat eaters are probably not fully saturating their muscle with creatine. Yeah.

38:28Perry Wilson:So when people talk about taking a creatine supplement just to like get to brass tacks, there's kind of two approaches to this. So for people who are doing, who are taking this for like bodybuilding, the approach tends to be to take a lot for a short period of time, like as you know, 30, 40, 40 grams of creatine a day for some period of time and then return to a maintenance dose. For most people who would take this to kind of just generally improve their overall muscle functioning and so on, the typical dosage would be something like five grams a day as like a regular just to take five grams a day.

39:10Emily Oster:That's probably even a bit more than the average person needs. What will happen is that you pee out the excess. So, you know, you can think about whether it's worth it to you. It's not going to be harmful to take more. Those big bulky loading doses, be a little careful with if you've never done this before. There are some GI effects. You get some rumblies in your tumblies with creatine, even at the five gram dose. So if you have a sensitive stomach, be a little careful when you start out.

39:39Perry Wilson:And there's a lot of ways to get creatine. There's creatine in powder. There's creatine in water. There's creatine in gummy form. There's creatine pills. There's like a lot of different options.

39:50Emily Oster:Most of what you'll see is creatine monohydrate. All of the data that we talked about today was creatine monohydrate. There is this other form of creatine out there called creatine ethyl ester or something like that, that they argue like is absorbed better. There's no data on it. And there doesn't seem to be a reason to spend extra money on that.

40:06Perry Wilson:All right. So two downside questions people often have here. One is, does creatine make you retain water? So this is like I take a bunch of creatine and then I'm all of a sudden like a bloated water bag.

40:22Emily Oster:True or false? True. True. Oh, yeah, absolutely. Absolutely. So creatine is getting taken up by your muscles and water will flow from parts of your body that have less dissolved stuff in it to parts of your body that have more dissolved stuff in it. That's osmosis. And so water will move into your muscle cells when you start taking creatine as the creatine concentration in your muscle cells build up. And that actually swells your muscles a little bit. Like it's not you're not stronger, but it does it does kind of like maybe add a little definition. The studies show, you know, you're talking about two kilograms, so four to five pounds in the first week or two of creatine supplementation of water weight.

41:11Emily Oster:So be aware of that. And it does persist as long as you supplement creatine. So like if you're just doing your five grams a day, like you'll get that initial weight and you'll just sort of stay at that extra water weight. If you stop the creatine, then you'll have what's called diuresis and you'll lose some of that water. So, you know, don't freak out. You're gonna gain a couple of pounds and it's just water.

41:36Perry Wilson:Second question, is it bad for my kidneys? You're a kidney doctor. Oh, I love this question.

41:40Emily Oster:Can I tell a story? Can I tell a patient's story?

41:43Perry Wilson:Do you love the kidney so much? Yeah, please tell a patient story.

41:45Emily Oster:I am a fellow, a kidney fellow at the University of Pennsylvania. And this woman comes in and consults. She's like this 85-year-old Russian grandma. Whatever you're picturing, that is correct. That is how she looked. Okay. And she comes in and she has a creatinine value of 10. Now, creatinine is a blood test that we use to assess kidney function. creatinine is a metabolite of creatine so the creatine that's in your muscle breaks down and forms creatinine at sort of a steady rate because everything breaks down and your kidneys excrete the creatinine fine as your kidney function worsens because they can't excrete as much the creatinine in your blood goes up so the higher your creatinine is the worse normal creatinine is around one just to keep things simple a level of creatinine of 10 is like your kidneys aren't functioning at all.

42:41Emily Oster:You need to be on dialysis. You're dead. Dialysis, right? You need a transplant. This is terrible. So I'm waiting for her to come in. I'm ready to like have a conversation with this 85 year old Russian grandmother. It's like, okay, I need to admit you to the hospital today. We're going to start dialysis. We'll get you on the, she's probably too old for transplant. Like it was going to be a whole thing. And she walks in and she looks great. She's just spunky, old, small lady. And I'm looking at her other laboratory parameters. I'm like, her potassium's fine. It's very unusual for someone with advanced kidney disease.

43:14Emily Oster:The acid-base balance in her blood is totally stone-cold normal. Like, it didn't make sense. So I'm talking to her, and it comes out eventually, as I'm asking her about her diet, that she has a trick to staying healthy in life. And what she does is she takes a giant pot roast, essentially, at the beginning of the week and boils it and boils it and boils it and boils it until there's basically nothing left. She takes out all the like gristle and whatever is left. And then she takes that boiled stuff and she boils it and boils it and boils it until she has a thick slurry of like meat, meat juice.

43:55Emily Oster:okay and she drinks like a cup of this thick slurry of meat juice a day to stay strong and virile and what was happening is she was ingesting just herculean amounts of probably creatine but also creatinine because the act of cooking is going to break down the creatine from the meat into creatinine as well. So she was ingesting this huge amount of creatinine. Most people, muscles produce about a gram of creatinine a day. So if you make a gram of creatinine, you pee out a gram of creatinine, you stay in balance, everything's hunky-dory. She was clearly taking in about 10 times that because her serum creatinine, she was totally fine.

44:40Emily Oster:She had no kidney dysfunction whatsoever. So no, there is no risk of kidney dysfunction with creatine. However,

44:48Perry Wilson:sorry, did you tell her to stop doing this? Or this was like totally fine? She seemed fine.

44:54Emily Oster:But I did. I did tell her I was like, listen, every time you get your blood tested, they're going to tell you that your kidneys are failing. So yes, creatine supplementation will increase your creatinine in your blood. And that is our marker of kidney disease. So when you get your blood tested, if you're supplementing creatine, it will be higher and certain doctors who are less informed might worry about that. There's no evidence it harms your kidneys directly. There is another blood test for kidney function called Cystatin C, which won't routinely get run, but you can ask for. And that's independent of creatine and creatinine and whatever.

45:36Emily Oster:So like, if you really want to know for sure, if you're nervous and you're on creatine, just ask for a Cystatin C. It's an approved test and you can get like a better estimate of kidney function.

45:45Perry Wilson:That's a great story. I, before we end, I want to end with the bad news for you, uh, which is that creatine, although influencers will tell you it does, creatine does actually not affect your hair loss or your hair growth.

46:02Emily Oster:There's some discussion of both hair loss and hair growth. Talk to me about this. I mean, I'll take no effect on hair any day, although I'd love hair growth if you can give me some of that.

46:14Perry Wilson:There is sort of one small study that suggests that maybe creatine would increase testosterone and then lead to possible hair loss. But then there's many other studies which show there's no effect on any of these things. And so but also no effect in the other direction.

46:32Emily Oster:Yeah, there are some observational studies, too, which are interesting. that correlate creatine and hair loss. And we always love to talk about confounders, which are like third variables that explain an observed association. And there are a couple of things here. I can speak from personal experience. One is that as men age and start to worry about their muscles and have a little more time maybe after the kids are older to go to the gym and start taking creatine is also the age in their life when like the hair is not as thick as it used to be. And then in the slightly more sinister side, you know, creatine is used extensively in the bodybuilding community.

47:12Emily Oster:And there are other substances that are used rather extensively in the bodybuilding community that certainly do result in hair loss like the androgenic steroids. So that's another thing that is often not disclosed when taking a survey about your supplement use and your hair loss. Indeed.

47:31Perry Wilson:All right. I think that's it for creatine. Let's do the smash or pass. Perry, smash or pass on the creatine?

47:39Emily Oster:So full disclosure, smash. I take my five grams of creatine in gummy form a day and I'm going to just, whether it's placebo or not, I take it. I go to the gym and I'm doing it for muscle. And if it helps my memory, that's great. But I am not sure that it does. Emily, smash your pass.

48:00Perry Wilson:Smash. I also take my creatine every day. I even got my husband to take it. It's the only weird supplement thing I managed to encourage him to do. And yeah, I tend to take it in powder form, five grams a day. And I also am feeling I'm maybe relying on the placebo effect, but it's totally fine. Okay. I tried powder form.

48:22Emily Oster:How do you, what do you put it in? Hot water. Just a cup of hot water? Doesn't it taste gross?

48:28Perry Wilson:No, I don't think it tastes bad. I understand some people feel this way. The creatine that I typically consume, which is thorn creatine, does not taste bad. I don't think it tastes like anything.

48:39Emily Oster:To me, it tastes super bitter. I get whatever they sell at Costco because – not an ad, by the way, but Costco, if you're listening, I love you. I get whatever they sell there. But it is very bitter. And I used to put it in my coffee and then I missed the fact that I enjoyed drinking coffee. Then it makes your coffee sad. Yeah, yeah. And I don't like sad coffee. I like happy coffee. So I'm on gummies now.

49:01Perry Wilson:I will say these creatine, these creatine gummies are actually really delicious. Also not an ad, but they are, they are good. So if you don't like the way the powder tastes, I recommend gummies.

49:10Emily Oster:All right. After the break, we will get to your question of the week.

49:20Hi, Emily and Perry. This is Elizabeth from Boston. So as my elder millennial heart is mourning James Van Der Beek, I'm realizing that I should be close to scheduling my first colonoscopy. I'm 42. Is it time yet?

49:37Emily Oster:Thanks.

49:38Perry Wilson:So the recommendation is to start for somebody with sort of typical risk factors is to have a first colonoscopy or a first colon cancer screening at 45. So that is the standard age. So if you are 45, now is the time. If you are younger than 45 and you have significant risk factors, that could be the time. But you really do want to start this. I mean, colon cancer screening is not as bad as you think. You can talk more about that if you want. But it is great. I'm going to go. I'm going to go.

50:10Emily Oster:Actually, I also thought it was great. OK, I actually thought it was great. The cocafol is awesome.

50:17Perry Wilson:just to be clear when you have a colonoscopy like a lot of I think a lot of people find this very scary but the procedure the worst part of this is you drink some terrible tasting drink and then you poop for a bunch of times you're actually totally fine you know you can't eat that much for a day and then you go when you take this amazing propofol like nap and it's so nice and then they wake you up and you're done and then you go home and take another nap and eat something and it's great.

50:45Emily Oster:Yeah. Right? It's great. Nothing to worry about. 45 for people of average risk. Talk to your doctor if you're at higher risk. If you had a family member that had colon cancer, you should start screening 10 years before the age that they were diagnosed. Or if you have other high risk factors, the recommendation is age 40. Colon cancer is occurring with increasing incidence in younger people. That is something we'll talk about in some more detail in the future. But yeah, get it done.

51:13Perry Wilson:And I will say that when you are 45, many people face a choice about getting a colonoscopy or using Cologuard, which is a system where you poop in a box and you send it off and it tests for markers that could be associated with, that could predict colon cancer. Cologuard is very good at detecting colon cancer and advanced adenomas. A colonoscopy is better at, is much better at sort of earlier stage stuff. And so it's a little bit of a trade-off for people depending on your risk factors. One thing I think many people are not aware of, I will just say, is if you do the Cologuard and you screen positive, your insurance may actually not cover the colonoscopy afterwards.

51:55Perry Wilson:And so that is something to find out before you do this. It's like a weird thing about diagnostic versus screening. And so that is true for some insurances.

52:04Emily Oster:Oh, interesting. And Cologuard you have to do every year.

52:07Perry Wilson:Cologuard you have to do every year. And colonoscopy, if everything is good, in principle, you could go 10 years between them. All right, that's it for us today. Stick with us next week when we will ask, what's the deal with protein? Wellness Actually is produced in association with iHeart Media. Our senior producer is Tamar Avishai. Our executive producer at iHeart is Jennifer Bassett. Our theme music is by Eric Deutsch. And our content is for educational purposes only.

52:36Emily Oster:If you like the show, help other people find us. Leave a rating and review on Apple Podcasts or your podcatcher of choice. And help us spread the word about the show. You can follow us on Instagram at wellnessactuallypod. And don't forget, we want to hear from you. Head over to wellnessactually.fm and leave us a question for our mailbag. Or suggest a topic for a future show. We'll let the influencers have the last word. As you guys may know, we have more than 20 flavors of creatine. If you don't know what flavor to pick, Here are the top five flavors from the last 30 days. At number one, as usual, we have Pink Lemonade.

53:10At number two, we have Puckin' Blue Raz. If you like sour flavors, you are going to love this one. At number three, we have Pina Prada. At number four, we have Raspberry Watermelon. At number five, we have Glacier Gummy. There's a new flavor on the way, which mimics the White Monster Energy Drink. I cannot wait for that one to go live.

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