Fiber: Friend or Foe?

When you’re diagnosed with Crohn’s disease and having a hard time, your doctor will often put you on a low-fiber or low-residue diet. Same difference, really. Basically, eat soft, mushy, bland food – and lots of carbohydrates. Rice! Toast! Don’t eat a lot of vegetables!

And honestly, this works. Pre-digesting your food as much as possible helps your gut to rest. Cook your food. Chew your food. (And not in the gross mama bird-baby bird way, eww.)

For me, as I’ve navigated the SIBO/low-FODMAP diet oceans, I’ve sometimes doubled down on this idea, drifting into days when I ate very little plant matter at all. Just meat and fat, and maybe a little fruit or something on the side. It’s very easy to do when the wrong type of sugar sends your gut into a tailspin of gassy diarrhea.

But lest you think I’m going to do an about-face and preach the gospel of high fiber (or even worse, the RAW FOOD DIET), it turns out that eating less fiber is actually better for you. Too much fiber means such things as straining when you poop (no bueno), screwing around with your Nutrient Density QuotientTM, damaging your gut wall, and buying in to poorly-research nutritional theories (and nobody wants to do that now, do they?). TL;DR eat real, whole foods and you’ll get enough fiber.

However, let’s back up to “damaging your gut wall,” Or, as it is called by researchers1, “mechanical stress.” AKA: maybe why our guts hurt so bad after we eat food.

What this means is that fiber damages the cells in your gut, which in turn respond by producing more mucous. This might be good, if more mucous automatically meant better health, but that is unlikely since a common tell for poor gut function is an abundance of mucous in the toilet.


The scientists aren’t certain how many times cells can take a hit, but they suspect turnover is so high because of the constant injury. Potentially caustic substances, such as alcohol and aspirin, can produce so much damage that natural recovery mechanisms can’t keep up. But they doubt a roughage overdose is possible.

My gut can tell you that a roughage overdose is indeed possible. So can my coworkers, based on the day after I ate a raw kale salad with dried cranberries.

Also interesting is that aspirin–banned by my first GI–and alcohol–self-imposed ban due to its gut-destroying properties–are just as bad.

Don’t just take my word for it, though. Let Dr. Eades tell you the whole story.


1 Full study at PLOS Biology

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