Protein: are you getting enough?

0:00Welcome to ZOE Science & Nutrition, where world leading scientists explain how their research can improve your health.

0:10you've probably heard there are three main components of food carbs fat and protein right what's your immediate reaction as i say those words if you're like most people it's probably carbs those are bad fat even worse protein well i should probably eat more of that But we're always safe with protein. As a result, food packaging everywhere is plastered with the slogan, high protein. What they're really trying to say is, hey there, I'm good for you. Food manufacturers know this, certainly sell products. For this reason, many of us are trying to eat as much protein as possible. We eat pounds of meat and fish, guzzle powdered protein shakes and munch down high protein bars.

1:01As a result, we consume far beyond the recommended allowance of protein each day, confident we're making healthy choices. But are we? It turns out everything we've been told about protein may be wrong. In today's episode, we'll hear what the latest science says from one of the world's leading nutritional researchers, Professor Christopher Gardner. Christopher is the Director of Nutrition Studies at Stanford University, a long-term member of Zoe's Scientific Advisory Board and the lead author of a recent peer-reviewed paper on recommended protein intake in nutrition review. Be prepared to be surprised.

1:41Christopher, thank you for joining me today. And it's such a treat. We've known each other, I think, for more than five years now. And for our listeners, Christopher is one of the top nutritional scientists in the world, carrying out a whole series of big interventional studies in humans, which are randomized control trials, which is very rare. He's been a longtime member of the Zoe Scientific Advisory Board. And he's also been one of the authors of a major review of protein requirements for nutrition review. So there's no one better to talk about protein, which is one of the topics where we've had the most questions from our listeners and members of anything that we've touched on this podcast.

2:21So I think it's going to be a lot of fun. Thank you for being here with us. Absolutely. This is a topic that is near and dear to my heart. Many myths to be busted. Well, on the topic of myth busting, why don't we start with our usual quick fire round of questions from our listeners. And just to remind you, Christopher, the rules are quite simple. You can say yes, you can say no, or if you have to, you're allowed a one sentence answer, but no more than that. And we know that this is the hardest thing for any professor to do, but are you willing to give it a go? Yes. All right, you've got the hang of it already.

2:58Okay, Christopher, will I die if I don't get any protein in my food? Yes. Do animals contain special proteins that you can't get from plants? No. Should we all be worrying about getting enough protein? No. Are protein shakes and protein bars healthy for most people? Compared to a tablespoon of sugar, healthier. But I was saying compared to what? Compared to food? No. I told you it was hard for a professor to answer these questions. And the last question, can eating more protein help with weight loss? No. Okay. I think a lot of people are already going to be surprised. And I hope we're now going to unpack this in the rest of the podcast.

3:45Maybe we could just start at the very beginning. So I think most of our listeners will feel they know what a fat is, right? They're thinking of like an oil they cook with or butter or, you know, maybe the fat in a piece of meat. And I think almost everybody feels sort of confident about a carb, right? It's like it's bread or potatoes or something like that. I think, however, if a lot of people are like me, they're actually quite unclear really what protein is, except, you know, they're sure there's quite a lot of it in a piece of meat because their mom always said, eat your meat and get your protein.

4:12So could you just sort of start at the beginning? What is protein and why do we need it? Sure. So when it comes to fat and carb, that's really most of our fuel. When it comes to protein, it's more of our structure. So all of our cells and our organs and our hair and our fingernails, all of that is structural protein. All the enzymes that are in our body that catalyze reactions and make metabolism move forward, those are all proteins. Many hormones are proteins. There's actually a huge list of functional things that proteins do. And to take it to one next level, maybe this is helpful, maybe this is not.

4:53All proteins are made of 20 amino acids in the human body. And I like to think of them like Scrabble letters in the Scrabble board game or the letter somebody would put on the marquee of a movie theater. And for perspective, there's a couple of them that are only three amino acids tied together, which would be called a tripeptide, but that would be unusual. The largest one I know of is something called maybe Tintin. It's 35 ,000 amino acids strung together in a specific chain. I was thinking about this like words and these amino acids like letters, but you're saying these words can get really long and you need a lot of them.

5:28but fundamentally you can make any word, like any protein out of just this limited number of these amino acids. One could be a limerick, you know, and one could be a haiku. It's just amazing how they differ in length. And what's critical is not only that the specific amino acids one after another be perfect, like if you were spell checking your writing in a document, it would say, nope, that word doesn't work. So it has to be perfect. And then when the amino acids are arranged in a certain configuration, these long strings of amino acids twirl and twist and conform. They actually have to be side by side in just the right way.

6:05And if you change that and unravel them, which happens in your stomach with a low pH, it happens with heat, you inactivate the protein. And if it was going to have some functional purpose like an enzyme or a hormone, it no longer works. And now it's kind of just like fuel. Now you can just break apart the single amino acids and use them, but it can't function like it was going to. And that's why protein is so tricky. So many things that it does, so many ways to activate and inactivate it. And so Christopher, to make sure that I've got this, because that was a little scary, what you just described, you're basically saying we eat food with proteins in it.

6:43We break it down. There are like 20 of the potential like building blocks, like lettuce, which is what you're calling these amino acids. And then our body makes almost everything we're made of out of those like 20 letters in unimaginably complex sort of combinations. I like the way you said that. And let me add one twist to this, which is pretty interesting. There's very few rare exceptions to this. But when you say eat an animal protein or a plant protein, and it goes into your digestive tract, you can't absorb those amino acids into your body until you break them down to their single amino acid levels.

7:22And then you absorb them, travels through your body, reassembles them. Can't remember where it came from. Oh, did this come from a cow? Oh, did this come from a pig? Oh, did this come from broccoli? No clue. It's like, oh, it's just this amino acid. I don't even care. It came from a supplement. Can't even tell it's just the building block. Got it. So this is like I ate Shakespeare or I ate a comic book. My body just breaks it down to letters. That just makes the protein sound even more important. Follow on natural question about this is I think one of the things that we've learned on this podcast is that our body has this amazing ability often to swap carbs into fat.

8:00So it doesn't really matter what you eat always because your body will make what you need. Can't we just make these letters, these amino acids when we need them? Yeah, I bet you a lot of people listening have heard of essential and non-essential amino acids. I think it's a pretty non-essential question for all of your listeners, but I'm going to say it anyway. While carbohydrates and fats are circulating in your body, the basic structure of those is built on carbons of different lengths, and they have very complex metabolic pathways. And at certain points in carbohydrate metabolism and fat metabolism, You can borrow one of these molecules, put a nitrogen on it in the form of an amino group, which means a nitrogen with three hydrogens.

8:45An amino. Amino reflects this nitrogen portion. You can actually make 11 of the amino acids by borrowing something from fat and carb and putting this ammonia amine group on it. And likewise, if you were breaking protein down because you had enough for the day, which I hope we get to later because most people eat more than enough. If you take the amine ammonia nitrogen group off, you can put it right back into the carbohydrate or the fat metabolizing chain. And that works for 11 amino acids. For nine of them, there isn't a specific place you can borrow it from in your body. And so since you need all 20 for just about every single protein that you synthesize, you also have to get the nine essential ones.

9:31And Essentials simply means you can't assemble the whole thing yourself. You got to make sure I got that, Christopher, because it got a bit scary in chemistry again. You're saying there are these 20. Actually, we can make some of them ourselves. But actually, I think you would say nine of them. We can't make them. So you've got to eat them. You have to get those nine in order to do essential things inside yourself. Is that? Did I get that? All right. So protein is really important. We need to get some. Let's talk about how much we therefore need, which was the number one question that we had as we were preparing for this show.

10:05You're going to just have to stop me all over the place and get me to explain it in English because this will be harder. But basically, I'm going to take one big step back and say, if you've eaten enough calories for the day, you've got enough protein. Just so stop obsessing about protein. Proteins in everything, all 20 amino acids are in all plant foods. big myth to bust here and all animal food so if you're simply getting enough calories with a reasonable variety in your diet like if you only ate rice all day you wouldn't get enough if you only ate cassava all day you wouldn't get enough protein but you also wouldn't get a lot you also wouldn't get enough of other nutrients so let me tell you how people figured out how to get enough protein this is disgusting are you ready so i got we're ready i got my phd doctorate at uc Berkeley in California.

10:57And they were one of the sites that did some of the initial trials in the 50s, 60s to establish this. And the fifth floor of my building, Morgan Hall in Berkeley, was called the Penthouse. And we got human subjects that were conscientious objectors to the Vietnam War. And they volunteered to live up there in blue zoot suits. And the scientists would sequentially lower their protein successfully down to zero and give them just carbs and fats. And then they would raise the protein back up slowly in their diet. And every single day, they would remove the blue suit and they would vacuum it for all the hair and skin cells that sloughed off during the day.

11:43They would collect all the poop, all the pee, all the nose blowings, anything that left the human body was collected. Now we already talked about this nitrogen thing in protein and the initial studies were interestingly called nitrogen balance studies. And instead of like analyzing amino acids in poop, analyzing amino acids in pee, analyzing amino acids in hair, you just burn it all up and analyze the nitrogen. That's how much you can calculate how much protein left your body. And then because they were nutrition scientists, they were calculating the amount of protein or nitrogen going into the body from food.

12:22So they knew how much was going in and how much was going out. They raised and lowered it for each individual until they were in balance. But Jonathan, when they did this for a bunch of people, as you might imagine, what they found out is, oh my God, this person in the room needed more than that person in the room. And when they combined their data with a bunch of other folks who had done this same disgusting thing. They came up with, in math, get ready for this, a normal distribution curve, which means a couple of people needed very little, a couple of people needed a lot. There's a bell curve.

12:55So there was an average in the middle. They did arrive at what would be the average. And it's called the EAR. It's very specific in this huge nutrition book, the estimated average requirement. Now, here's an important question for you to think about. When you want to come up with protein recommendations for the country, what would you suggest recommending? Would you recommend the estimated average requirement? Because if everyone in the country got exactly the estimated average requirement, by definition, how many people would be deficient? Half. Because it's the average amount. If you only get the average amount, the half of you that are above average, not just intelligently, but from protein requirement would be deficient.

13:41And so this happens in protein and all the vitamins and minerals, Jonathan. And so when the U.S. comes up with recommended daily allowances for protein, vitamins, and minerals, the standard approach is to take two standard deviations above the average. And in mathematical terms, that means you've picked a number that should be adequate for 97.5 % of the population. And there might be a couple people in the tail that need even higher than that, but it would be so few that you're pretty safe recommending that amount. Now, not only is that amount adequate, but another math thing to keep in mind here is if really everybody in the US or the UK, wherever, got exactly that 97.5%, two standard deviations higher, how many would be exceeding their requirement?

14:30Oh, actually, like 97%. So just to make sure I'm with you here, Christopher, because you're moving at some pace. you're basically saying that when they came up with the recommended amount for protein, they basically picked the amount that makes sure that almost nobody would have too little. And as a result, you know, this recommended daily amount, which I've definitely heard from vitamins, right, and supplements, you hear that very often. But I think anytime you look on the back of a food label, again, you know, I've definitely seen that for almost everything. It's actually the amount that means almost everybody needs less than that.

15:08Yes. And so if you're getting the recommended daily amount, you don't need to worry that you're not getting enough. Actually, in a sense, you're getting more than you need for almost everybody. So where does this take us? At this time of year, many of us focus on supplements, quick fixes, or food fads to stay healthy. But one of the most powerful tools we have is something much simpler, sharing food with other people. The science is really clear on this. Eating with others naturally encourages us to slow down. which supports better digestion. People also tend to choose more nutritious, balanced foods when they eat together.

15:44It's one of those simple habits that makes a real difference to our wellbeing, especially at this time of year. That's why we've created the Zoe Holiday Hosting Guide. Our free guide is filled with cozy recipes that are perfect for sharing, hosting tips, and go-to-dinner party dishes from our scientists and nutrition experts. Think warm, relaxed evenings with the people you love, sharing delicious, nourishing meals that makes you feel good from the inside out. To download your free guide, simply click the link in the show notes or go to zoe.com slash holiday guide. That's zoe.com slash holiday guide.

16:22Okay, and so what that takes us to is they came up with a number that said 0.8 grams of protein per kilogram of body weight should meet that. And so I have a graph and a table that I can't show you because we have a podcast here, but for a lot of people, that RDA level would be maybe 40, maybe 50, maybe 60 grams of protein if you're heavier. So I have some US data that shows how much protein people eat in the US. And it's pretty much double the EAR or double the RDA, just eating food, not even trying. And so to me, it's sort of this American idea of, good let's see that's what the rda is but i know i'm above average so let me make sure i get some extra here it's like no you don't understand the concept it was built in to recognize that some people would need more and as a nutritionist when i teach students i have to say this is not an individual approach you should not look at the rda to see if you are meeting your individual requirement this is a population health approach so that if everybody were to get that amount almost no one would be deficient.

17:37And just as you were a bit surprised, every time I tell that story, the audience I explain it to is a little surprised. And so Christopher, you know, I am surprised because I've had this experience and I suspect there's quite a lot of people who've had this experience. So like the first time I ever went to a gym, which is about 10 years ago, and I had a trainer say, you know, this is what you need to do in order to get healthier, which is what I was interested in and fitter. One of the first thing you said is, oh, well, you need to eat more protein and you need to eat at least a gram per kilogram of protein if you're going to get any benefit out of the work that you're going to do at the gym.

18:17Now that number, because I think you just said it was 0.8 grams per kilogram was your recommended amount, which is like the maximum that anyone in the world basically needs. How did this happen? Why is there this controversy? Help me to understand why there's this pressure about feeling people need to eat more protein. Sure. Okay, so let's think about that one. So there are some flaws of this nitrogen balance study that I suggested. And so what happens in at least the US from all the databases I have is, and this is very consistent in all research studies that I look at, Most people get about 16, 17, 18 % of their calories from protein.

19:00It's so consistent. It's just amazing. And then you look at how many calories you eat to maintain your weight. And let's not go down this rabbit hole, but most people underestimate how many calories they eat. The data I have says women eat 2 ,500 calories a day and men eat 3 ,000. And I know a lot of your listeners are going to say, not me. I only eat 1 ,500 calories a day. We've done feeding studies where we gave people a certain amount of calories, and it's really 2 ,000, 2 ,500, or 3 ,000. If you take 16, 17, 18 % of those numbers, people tend to get about 1.5 grams of protein per kilogram body weight without trying.

19:42They're pretty much getting double the RDA. So now here's what happens if you're in the gym getting that double the RDA, right? Okay, so it's probably the 0.8 grams per kilogram met your need for enzymes, hormones, fingernails, and hair. You went to the gym to lift weights and gain muscle. So you probably want more than 0.8 grams per kilogram per day so you can put muscle on. Okay, so let me tell you how many extra grams of protein you need. So Jonathan, how ambitious would it be to put on 22 pounds or 10 kilos of pure muscle in one year? Would that be pretty good? That I have to say sounds quite ambitious.

20:25I think if anybody saw me, they would say totally ridiculous and impossible. But let's go with ambitious, shall we? Okay, ambitious. So 10 kilos, actually 70 % of your muscle is water. So if you were going to do that in a year, all you'd actually have to accumulate is three kilos of extra amino acids or 3000 grams of extra amino acids. Divide that into 365 days of the year and just roughly that means you would need an extra 10 grams of protein a day to keep, retain, in addition to meeting your maintenance needs to put this on. Now it's not quite a fair number because when you're in the gym lifting and working out, if you're working out really hard, you're actually breaking down some muscle using those amino acids and you have to replace them.

21:16So put another 10 grams on that. Say you needed an extra 20 grams a day every day for a year to put this on. In the US, people are eating like 30 or 40 extra grams a day over that 0.8 gram per kilogram every day, just eating food. And one more tidbit I have here is when you're working out hard every day, don't you eat more? You do. You don't eat just 2 ,000 calories. I have a Stanford football player who was in one of the Rose Bowl games. He was eating 5 ,000 calories a day because they work him so hard. He was getting 260 grams of protein every day. Without trying, he wasn't having shakes. He was just having food.

22:01So we should go to like which foods have that protein. But if we could go here, I have one more place to go is, well, wait, is that bad? What if you actually got more protein than you needed? What would happen to all that extra? Will it kill you to have more protein? What happens? Okay, so, but I wanna go down a rabbit hole just for a minute for a fun exercise. So think on an average day, you probably eat more carbohydrates than you need. And so once you've eaten some carbohydrate, the first thing it says, oh my God, does my brain need it right now? Nope, my brain's okay. Do my muscles need it?

22:35No, I'm doing a podcast with Jonathan. I'm just sitting here. I don't really need my muscles. okay well i have a storage depot for my carbohydrate and it's called glycogen and there's some in my muscles and there's some in my liver so i will try to fill up my storage capacity of glycogen stored carbohydrate so that i can have some later in the day and do you know how long it would take you to deplete all the storage carbohydrate in your body any idea do you are you a runner jonathan actually i don't know this if you're a runner no i'm i'm very good at sitting in my chair doing podcasts, but tell me how long does it last for?

23:10So I bet you've heard that marathon runners at 20 miles bonk if they don't have enough carbohydrate. That basically means you've used up all the glycogen that you stored in your body. It's only about a kilo. Okay, let's switch for a minute to fat. So let's say you ate more fat calories for the day and you used it for various things and mostly you burned it for energy. Where would you store that and how much could you store? And I'll save you the trouble here. You can store an infinite capacity of fat. Oh my gosh, you can store hundreds and hundreds and hundreds of pounds of fat in your butt, in your thighs, in your jowls, in the pads, in your fingers, endless capacity to store fat.

23:50It would take you an incredibly long time to use up all the storage of fat that you have in your body. So unlimited capacity to store fat, a very limited capacity to store carbohydrate. where could the extra protein go? So your trainer told you to do this. You ate all that extra protein. You made your enzymes, you made your hormones, you lifted your weights. And it was a little more than you needed, or maybe a lot more. And you're going to bed tonight. So where do you think you put it in your body? Is it in your spleen, in your liver, in your big toe, in your elbow? Where's your protein storage?

24:25Where is my protein storage? None. Every bit of it at the end of the day has the nitrogen taken off and it gets turned into carbs and fat you can't store protein in your body so the muscle heads who are having a lot of meat and regular meals and a protein shake and a protein bar are turning all that into carbs and fats at the end of the day i'm just going to turn it into basically fat that i lay down on my body is that what you're telling me. And yet the nitrogen will be taken off, your liver will turn it into ammonia and your kidney will excrete it and get it out of your body. And so you actually could suck out some calcium as it goes.

25:09And so some people say don't eat too much protein, it'll suck the calcium out of your bones. Let's not go down that rabbit hole. It probably doesn't happen. Most people with a healthy kidney can eliminate this just fine. You might know that if someone has an impaired kidney, one of the first things they do from a dietary perspective is they ask them to limit their protein because they don't want their impaired kidney to face the challenge of clearing more of this excess ammonia from the excess protein that most people get in a day. But to be honest, most people's bodies are set up to handle this, turn it into carbon fat and get rid of the ammonia.

25:41So for most people, eating that protein isn't necessarily bad for you unless you consider what came with it. So if this - Well, I was just going to say, isn't this like a i feel like this is a huge scam so basically there are all these products that are on sale that say you know no carbs 10 grams of protein or you know like no sugar 10 grams of protein and then you're telling me i eat it i haven't i'm already eating more protein than i need so my body is just going to turn that into carbs and fat and since i we know i already I'm eating as much food as I need. Like if I'm having that on top, I'm just basically going to turn it into body fat.

26:23Is that, have I got that right? And in the end, it all comes down to calories. So Jonathan, we just finished a fun little study with a master's student. We hope to expand on it. We got 22 Stanford graduate student recreational athletes who have been for five or six years working out every day. They're not competitors. They just work out all the time. They want to stay fit. 12 of them are runners. 12 of them are weightlifters. Six in each group were men, six in each group were women. For four weeks each, we had to meet an omnivorous diet, a vegan diet, or these plant-based alternative meats. And the outcomes, instead of my usual cardiovascular thing with lipids or blood pressure, whatever, were push-ups, pull-ups, bench press, lat pull-downs, leg press, and for the runners, a timed 12-minute run to see how far you could run.