AMA #77: Dietary fiber and health outcomes: real benefits, overhyped claims, and practical applications

**Peter Attia** (0:10)
Hey everyone, welcome to a sneak peek, Ask Me Anything or AMA episode of the Drive podcast. I'm your host, Peter Attia. At the end of this short episode, I'll explain how you can access the AMA episodes in full, along with a ton of other membership benefits we've created. Or you can learn more now by going to peterattiamd.com/subscribe. So without further delay, here's today's sneak peek of the Ask Me Anything episode.
Welcome to Ask Me Anything AMA episode number 77 In today's AMA, we break down the science of dietary fiber, moving past the sort of generic advice to eat more fiber to understand what it actually does to the body, where it's truly beneficial to health, how to use it effectively, and where its reputation may exceed the evidence. In this episode, we will discuss how different types of fiber-soluble, insoluble, viscous, and fermentable work in the body and how their distinct properties result in different functional outcomes, whether fiber meaningfully impacts satiety, weight management, and glycemic control, and how those effects compare with more potent tools, how certain fibers influence lipid metabolism and cardiovascular risk, and whether their magnitude of effect justify their reputation, what the mechanistic and epidemiologic evidence really say about fibers' role in colorectal cancer prevention, including the potential influence of short-chain fatty acids like butyrate, who might not tolerate certain fibers well, and how to tailor their intake accordingly, how to move beyond the simplistic goal of getting enough fiber towards a more strategic approach that maximizes its actual benefits. Now, if you're a subscriber and you want to watch the full video of this podcast, you can find it on the show notes page. If you're not a subscriber, you can watch the sneak peek of the video on our YouTube page. So without further delay, I hope you enjoy AMA number 77

**SPEAKER_1** (2:16)
Peter, welcome to another AMA. How are you doing?

**Peter Attia** (2:21)
I'm doing well. Thank you once again for having me.

**SPEAKER_1** (2:24)
Living life, happy, healthy, all is good.

**Peter Attia** (2:28)
Very much so.

**SPEAKER_1** (2:29)
That's good. People will be sad to learn who listened to our last full AMA. I do not think as of now you are the proud owner of an 87 Caprice Ghostbuster car. Is that correct?

**Peter Attia** (2:43)
Correct. The CFO vetoed the purchase.

**SPEAKER_1** (2:47)
Yeah. It's a shame. Maybe with enough outcry, one day, you can accomplish something where you deserve that car. I don't know if you can, but the hope is one day you can treat yourself to something nice, like an 87 Ghostbuster Caprice.

**Peter Attia** (3:03)
Or just an 87 Caprice.

**SPEAKER_1** (3:05)
You could say it could be a dream of yours. Maybe that's your dream. On that, we're going to talk about fiber, which has nothing to do with anything we just covered. But it's a subject we get asked about a lot, and we've never really talked about on the podcast before. And if you think about usually what we cover on AMAs or podcasts, there's some tie-in. We've looked at it some way before. But I think fiber is one of those topics we've never really dove deep into, and we get a lot of questions on it. And so we're going to cover what fiber is, where it can, can't be beneficial, how to think about using it. We'll look at all the various claims that people talk about, which is satiety, weight management, glycemic control, cardiovascular health, colon cancer prevention. All things from the outside would be very important and very nice to have. And so we're going to look at all those and then close on some practical takeaways of how people can apply all this as they think about fiber in their life. So with that said, anything on fiber you want to add before we get rolling? Nope. Why do we want to talk about fiber? Why do we think it's worth spending an AMA on?

**Peter Attia** (4:17)
It really comes down to the importance of occasionally checking things that we view as axiomatic or dogma. So the general consensus is that fiber is good, the more you eat, the better. End of story, case closed. But if we're going to be critical of our beliefs, we have to acknowledge that the recommended daily allowance for fiber is almost entirely based on epidemiologic studies. And we know that epidemiologic studies have left us on the wrong track with many of their recommendations. Not all.
And of course, just because epidemiologic studies point to something being the way to do it, doesn't mean it's wrong either. But basically, we just don't have as much clear causal evidence as we would like to make the type of recommendations that we're making. Now, I would say historically, it's not that I haven't known this. I've just let it slide because my view has been, what is the harm? So what if the epidemiology says you should be eating whatever, 50 grams or 30 grams a day? What's the downside in that? But look, there's been some polarizing discussions on this topic lately, and you seem to have people accumulating on either sides of this debate. You've got the, you need zero fiber crowd, obviously more on the carnivore side of the diet landscape. And then you've got the, if you're not getting 50 grams a day, you're probably going to die in the next week or so. Obviously, I'm being facetious, but that's basically the way the discussion is shaping out. So, I think with that said, we need to take a closer look at the data, so that an individual who is in the 97% of the population, who chooses not to be completely dogmatic and extreme, can make a well-informed decision. And frankly, that starts with me. Like, I actually care deeply about this topic on a personal level, because I'm actually not sure how much fiber I should be eating.