Peter Attia

They might be exercising more, they're much less likely to smoke, they're probably getting more sleep.

And while a number of these things can be statistically modeled and corrected for in what is referred to as an adjusted analysis, it is essentially impossible to capture every one of these things and statistically correct for them.

In other words, you are very likely to be capturing other healthy habits when you're trying to simply measure one thing.

And of course, that's the hallmark of doing experiments.

The reason an experiment, particularly a randomized experiment,

and ideally a blinded randomized experiment as the gold standard is so important, is because it allows you to isolate one variable at a time.

And epidemiology does not allow you to do that.

I think the other reason that epidemiology is challenging here, and this is

again, not unique to epidemiology, this is a common phenomenon in all nutrition research, is it is difficult to disentangle the potential impacts of fiber itself from the potential impacts of things that traffic with fiber, the other micronutrients and phytochemicals specifically, because of course fiber is found in plants.

And plants are presumably known to contain many things that provide some benefit, and therefore it's difficult to disentangle them.

I would say those are the two main reasons why it has been not easy to come up with, I think, some more concrete points of view on this particular nutrient.

I think this is actually a very important point.

And this is an AMA where I found myself learning a lot in the preparation for it with the research team.

So in nutrition, dietary fiber refers to a diverse group of compounds that make their way to the large intestine.

So why is that relevant?

Well, if you think about how your digestion works, put things in your mouth, digestion actually begins in the mouth.

You've got these enzymes in the mouth that are already starting to break things down, but mostly the mouth is for mechanical breakdown.

The stomach then undergoes more of a breakdown, right?

So now you've got this high acid environment and other enzymes in the stomach that break things down further.

The stomach then exits the food stuff into the proximal part of the small intestine called the duodenum and then ultimately ilium jejunum.