Does the paleo diet hold the secret to health?

0:00Hello, and welcome to Zoe's Science and Nutrition, and our special daily series about diets. Each day this week, we're examining one of the world's most popular diets, putting the latest scientific evidence under the microscope. We'll find out these diets' true impact on your health. I'm your host, Jonathan Wolfe, and I'll be joined throughout this series by Professor Christopher Gardner. Hello, Christopher. Good to be here, Jonathan. Christopher is a professor of medicine at Stanford University and the director of nutrition studies at the prestigious Stanford Prevention Research Center. He's one of the world's leading researchers on how our diet impacts our health.

0:33So what's on our plate today, Christopher? In episode three, Jonathan, we're traveling back in time and ditching every food introduced to our diet since farming began in favor of eating the Stone Age way. So Christopher, which food groups get the chop and why? Oh, now we've eliminated dairy and all grains and all of the hard beans that you have to cook, not like green beans and yellow beans, but the dried beans, the chickpeas, the lentils, the pulses. And why is that? Well, because these weren't around before the agricultural revolution that happened hundreds of years ago. They weren't around at a specific period in life, the Paleolithic period.

1:22And so what do we call this diet? The Paleo diet, which came to the attention of the public through Lauren Cordain, who's a really interesting scientist who looked back and said, you know, just intuitively, wouldn't it make sense if we ate a diet that we evolved on? And how long ago? Oh, thousands and millions of years ago. Hi, I'm delighted that you're here to find out if eating the Stone Age way really does have health benefits. If you haven't already, please hit follow in your podcast player so you'll know whenever a new episode arrives. This will help us to continue our mission to improve the health of millions.

2:03So that sounds sort of logical, Christopher. we often talk about this idea that maybe what we're eating today isn't really in tune with the way that we evolved. And I guess you're saying like we actually only invented agriculture relatively recently. Is that the theory? So maybe we haven't completely adapted to the foods that we've managed to grow since then? Yeah. So the grains from the agricultural revolution is just a couple hundred years ago, but the dairy actually goes back thousands of years. It wasn't available paleo. There was some genetic mutation that happened. Really, a lot of the world is still lactose intolerant, but it was European, Scandinavian folks that evolved to be able to be okay with dairy.

2:45But eliminating dairy and grains and beans is a huge proportion of the global diet right now. And so for people listening to this, what is it about the idea of an ancient Stone Age diet which sounds so appealing? It's appealing. Oh my God, that's what we evolved on. So that's fine. So what's left after you take those food groups out? So you could have meat and you could have fruits and you could have vegetables that grow above ground, not so much starchy vegetables. And so there's a legitimate concern with too much starchy vegetable. That's just a lot of glucose without a lot of other nutrients coming with that sometimes.

3:29But it's a pretty limited supply of nutrients. And to me, the meat is the most interesting one. So evolutionarily, I think the fruits and the vegetables are probably pretty similar, maybe roughly speaking to paleo times. But the meat, I'm trying to think of the paleolithic man or woman running after the mastodon or the saber-toothed tiger with a stone. I'm pretty sure we ran away from the saber-toothed tiger, didn't we? I think so. But I mean, to eat meat, you had to catch them and bash them over the head and kill them and cut them up. And yeah, OK, so we don't do that anymore. We go to a fast food restaurant and we took the bun off.

4:10Yeah, I'm paleo. I had a fast food hamburger without the bun. So I'm paleo. And that just cracks me up. And so what's the difference? Why do you think that isn't the same as what our Stone Age ancestors would have been eating? We certainly know that livestock these days is grown 99 % for the most part. For maybe beef, it's a little less than that, 90%, 80 % in these factory farms where the meat isn't grazing. The animals aren't grazing on grass and especially cattle type meat who have ruminant stomachs, which are supposed to do that and digest that and ferment that. We're feeding them corn and soy in factory farms, which actually kind of makes them sick.

4:53It gives them stomach problems. They have to get antibiotics for this. We ended up making very fatty meat by doing this. So when they eat a lot of corn, which their stomachs weren't meant for, we get a fattier marbled meat, which as I understand it, decades and decades ago, somebody said, oh, we're going to have to kind of convince the public that this marbled meat is better. And it's marbled because we're feeding them corn and they're not getting grass. So it's just not the same meat as grass-fed meat was long ago. Got it. So you're saying you're now eating lots of meat, but this meat is sort of different from the past.

5:31What are the theoretical health benefits if you were following this paleo diet? Yeah, so if you were getting rid of carbohydrates from the grains, we know a lot of people, the grains that they eat are the simple ones. It's the added sugars and the refined grains that we're cutting out. Potentially, there's a benefit to getting rid of dairy, which comes with a lot of saturated fat, although that's a much more complicated topic. But it is true that most of the world is still lactose intolerant to this day. So I'm not too sad about eliminating dairy. That would be okay. The beans, I'm really sad about.

6:09So getting rid of these beans because you have to boil or prepare beans in ways that weren't available in Paleolithic days, lentils, pulses, chickpeas, soybeans. Those are powerhouses of nutrients, fiber for the microbiome, all kinds of things like that. I would hate to give those up just to be paleo and have your burger patty without the bun. And so what are the downsides of following this diet today? So when you do go paleo and you're eating a lot of current meat, you're getting a lot of saturated fat that's been processed. You're getting sandwich slices, deli slices, processed meat, which raises blood cholesterol.

6:50It's been linked to cancer risk for the processed meat and raises LDL cholesterol if you're getting a lot of saturated fat. So those would be the immediate downsides. And less fiber for your microbiome, which we're just starting to appreciate, is a really important part of our health profile. And then how well do you think this like paleo diet actually matches to our own paleolithic diet? Because I know having spoken on a few podcasts to people actually go out and still visit people who are living sort of this sort of hunter-gatherer life. interesting they talk about these very high fiber diets yes which doesn't sound at all the same as they were just living off meat and you know a few berries yes so my colleague justin sonnenberg at stanford studies the hadza these tanzanians who go out looking for meat all the time they get a lot of physical activity doing this not the physical activity of getting in your car and driving to a fast food restaurant and driving home.

7:52They often come back without meat because it was too hard to catch something. And they eat a lot of tubers and get a lot of fiber. And a tuber is sort of a bit like a... A starchy, below ground, potato, squashy kind of thing. And you just, you can't eat paleo unless you're going to go run around with a loincloth and a spear or some arrows and go catch some wild meat, which doesn't exist. And so the reality is they're not eating the same, like this sort of like 70 % meat or diet? No, the reality is different from this idea of the paleo diet. Is that what you're saying, Christopher? Yeah, I'd be totally supportive.

8:28Everybody eating it who could get out there and go hunt their own meat. And you know that would be a very small number of people and a small number of servings. Got it. But it means that there's this idea of how we ate in the past is actually quite at odds with sort of the reality. Yeah, you can't do it. I mean, if you go way back, there's actually an old type of corn that had six corn kernels on it. I think it's called tziozinti, a name like that. And, you know, the agricultural corn that we have today is bred to have all the sugar in it. You can't eat paleo corn. You can't get paleo meat. You can't.

9:05Yeah, it's just not available today. In principle, it might sound good, but you really can't eat that way today. Got it. And your actual paleolithic diet was one which is much higher in fiber and in fact, sort of carbohydrates, I guess, than this paleo diet. And involved a lot of physical activity. In order to get it because you're working hard. So given all of this, what's your verdict on the paleo diet? I'm not a fan. And this is, again, one of these things we're talking about, as Lauren Cordain described it in a book. In principle, there are some positive aspects to paleo diet, but as most people don't follow it as intended.

9:44They follow it practically speaking, oh, this means I get to eat meat. And I will cut back on my grains and dairy, but I'm not going to make a lot of overall healthy choices. So the way they tend to follow the paleo diet tends to not be very healthy. Brilliant. Thank you, Christopher. Thank you, Christopher, for our time travel into the paleo diet in today's conversation, part of our special series of daily episodes about diets and our health. I'm Jonathan Wolfe. And I'm Christopher Gardner. Join us tomorrow when we're ditching even more plants and talking about the carnivore diet. As always, the Zoe Science and Nutrition podcast is not medical advice.

10:25It is for general informational purposes only. See you next time.

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12:01Okay.