Moment 167: 6 Foods You MUST Eat To HEAL Your GUT!: Dr Will Bulsiewicz

Steven Bartlett (0:03)

You've repeatedly talked about fiber and this thing you called short chain fatty acids. In your book, you said you believe that they're the most healing nutrient in all nature.

Will Bulsiewicz (0:12)

I think that's actually true. And I also would characterize them as the most anti-inflammatory molecule that I've ever come across.

Steven Bartlett (0:20)

And am I right in thinking we eat fiber, the bacteria in our microbiome breaks down that fiber, and it produces this thing, these short chain fatty acids? Is that it?

Will Bulsiewicz (0:32)

The story is just getting started though. The story is just getting started because the issue is that that's the simple part. These magicians that live inside of us release these short chain fatty acids for us.

Steven Bartlett (0:43)

By eating fiber?

Will Bulsiewicz (0:44)

By eating fiber or resistant starches. But then those short chain fatty acids go to work. And our immune cells, our human cells have receptors to receive these short chain fatty acids and act upon the information that they receive. So you could think of them as like a signaling molecule in the sense that your gut microbiome is not talking to your body and telling your body what it wants your body to do.

Steven Bartlett (1:11)

So it's training it.

Will Bulsiewicz (1:12)

Yeah, but it has the ability to like flip genes off and on. It has the ability to turn down your immune system. So as an example, when I think about autoimmune conditions, if we were to get like super into the details of autoimmune conditions, what you would discover is that we need more short chain fatty acids to empower these specific cells called T regulatory cells. And those T regulatory cells would actually turn down our immune system and protect us. So and it's not to say that autoimmune diseases are exclusively the result of a fiber deficiency.

There is certainly a genetic component, but there was a genetic component 200 years ago, 300 years ago. And yet these conditions really weren't that much of a problem back then. So many of these conditions didn't have a name until the last 100 years. And the emergence of them, many of them have increased 500% in the last 50 years. Why would that be? It clearly is not genetics. So it has to be related to our diet and lifestyle. And ultimately, when we talk about our diet and lifestyle, we're talking about our microbiome.

Steven Bartlett (2:18)

And really, one of the most important places to start, as you say, is with the fiber.

Will Bulsiewicz (2:22)

I think so.

Steven Bartlett (2:23)

You said earlier on we have to start slow and low with fiber.

Will Bulsiewicz (2:26)

Yeah.

Steven Bartlett (2:27)

And that's because we've got to build up those microbes that respond to the fiber and turn it into the short chain fatty acids, right?

Will Bulsiewicz (2:34)

Your gut is like a muscle, right? Like this is the way that I want people to understand this. Your gut is like a muscle, and a muscle is capable of work, but it has limitations. And the more that the muscle has been trained, the more capable of work it is. So if you lift weights, you might start at 50 kilos. If we're doing a bench press, you might start at 50 kilos. And then you go to 55 kilos and then the 60 kilos, and you work your way up. And that's the process of growing strong. And your gut works the exact same way. So if you expose your gut to food, specifically a diverse mix of different foods, you are training your gut. And your gut will become more capable of consuming those foods over time. And then you can eventually get to a point where you don't have to then restrict based upon your capabilities, because the capabilities are limitless.

Now you can eat whatever you want.

Steven Bartlett (3:37)

And is all fiber the same?

Will Bulsiewicz (3:39)

No, not all fiber is the same. Fiber is a very generic word. Fiber is like the word protein. No one would claim that the protein in a fish is the same as a protein in a bean. Yet both of them contain protein. Fiber is unique to individual plants. There are many, many different forms of fiber to the point that we don't even know how many exist. So what we know is this. It's rather simple though, right? Given that despite that complexity, it's rather simple. All plants contain fiber.

Every single plant has unique forms of fiber. We do split it into two major types. These are again, umbrella terms. These are big labels. Soluble and insoluble fiber. The soluble fiber is the kind that dissolves in a drink. It disappears. You don't even know that it's there. Yet, typically, the soluble fiber is feeding the microbes. That's the prebiotic fiber. Insoluble fiber is the kind that's the grit. So, like, if you were to add it to a drink, it's not dissolving. It's gonna be there no matter what. You could boil the drink. There'll still be fiber in it. So insoluble fiber, most of the time, is not the prebiotic fiber, but it does still serve a purpose. It helps in terms of your bowel transit, which affects your gut microbes. It helps in terms of your bowel movements, which affects your gut microbes. It helps in terms of other things, such as your cholesterol and your blood fat control. So both types of fiber, both soluble and insoluble, have advantages. You don't need to worry about those individually. You just need to know that plants have fiber. Every single plant has a unique form of fiber, and every single plant will feed unique families of microbes as a result of this.