# Powdered Insoluble Fibers **URL:** \ **Category:** Factual Questions\ **Created:** [February 24, 2020, 7:32am UTC](https://boards.straightdope.com/t/powdered-insoluble-fibers/848425 "2020-02-24T07:32:07Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [February 24, 2020, 7:32am UTC](https://boards.straightdope.com/t/powdered-insoluble-fibers/848425/1 "2020-02-24T07:32:07Z")
Toss a handful of wheat at an open flame and you’ll get some singed wheat. Toss a handful of finely powdered flour at an open flame and fwoom. Insoluble fibers like wheat husks might act as fiber at a particle size like you get from whole wheat bread. If you turn it into a fine powder, the FDA might continue to believe that it is an insoluble fiber so far as the nutrition panel goes, but I am skeptical that we haven’t changed some of the fundamental aspects of what makes it operate as a good thing for your gut in that process. When you powderize something, you have massively increased its surface area relative to its volume. What might formerly have been resistant to digestion might now become digestible; what formerly might have acted like a little wall between your food and your intestinal wall, haphazardly, protecting some nutrients so that they make it lower into your gut will no longer be able to do so; if there is any form of scraping roll that insoluble fibers play in keeping your intestines clean (I don’t know that there is) that might go away. Is this something that has been researched? ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [February 24, 2020, 11:48am UTC](https://boards.straightdope.com/t/powdered-insoluble-fibers/848425/2 "2020-02-24T11:48:07Z")
Until someone who knows better comes along: A search term that returns academic literature suggesting that it has been studied is: insoluble fiber particle size Given that all insoluble fiber is not created equal (fermentable, phenolic, etc., and apparently size too) it appears to be complicated. AIUI most of the scraping, shielding, is due more to gelation, not the action if individual particles, but I’m out of my depth here and may but have the latest poop on how fiber works. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [February 24, 2020, 11:55am UTC](https://boards.straightdope.com/t/powdered-insoluble-fibers/848425/3 "2020-02-24T11:55:47Z")
> [@Sage\_Rat](#): > > Toss a handful of wheat at an open flame and you’ll get some singed wheat. > > Toss a handful of finely powdered flour at an open flame and fwoom. Toss a log on a fire it smolders/burns slowly. Reduce a log to sawdust and toss handful on a fire and it also goes “fwoon”. As you mentioned, all that is a function of surface area. > [@Sage\_Rat](#): > > Insoluble fibers like wheat husks might act as fiber at a particle size like you get from whole wheat bread. If you turn it into a fine powder, the FDA might continue to believe that it is an insoluble fiber so far as the nutrition panel goes, but I am skeptical that we haven’t changed some of the fundamental aspects of what makes it operate as a good thing for your gut in that process. Something like wheat husks are mostly cellulose, which are indigestible by human biology at any size down to individual molecules. The chief differences with the powdered version are that powders are more easily suspended in liquids/combined with foods to make consumption easier, and fewer identifiable bits in your feces. Powdering indigestible fibers do not make them digestible because their chemistry hasn’t changed and digestion is largely about chemistry. Increased surface area doesn’t change the chemistry. ---
**Author:** ![bump](https://avatars.discourse-cdn.com/v4/letter/b/7c8e57/32.png) [@bump](https://boards.straightdope.com/u/bump)\ **Post date:** [February 24, 2020, 2:10pm UTC](https://boards.straightdope.com/t/powdered-insoluble-fibers/848425/4 "2020-02-24T14:10:27Z")
ISTR reading an article sometime in the early 1990s that referenced a study where researchers fed test subjects insoluble plastic that had been milled to the same physical size/shape as insoluble fiber typically was, and checked the results. Apparently the role of insoluble fiber in the digestive tract is a physical one- it irritates/stimulates the colon or something based on its size/shape/texture and acts as a laxative. After a bit of googling, here’s something that references the studies: [Understanding the Physics of Functional Fibers in the Gastrointestinal Tract: An Evidence-Based Approach to Resolving Enduring Misconceptions about Insoluble and Soluble Fiber - ScienceDirect](https://www.sciencedirect.com/science/article/pii/S221226721631187X) (search for “Misconception #3b: Insoluble Fiber has High Water-Holding Capacity (Holds Water Like a Sponge) that Provides a Regularity/Laxative Benefit”) Soluble fiber is a different story, however. ---
**Author:** ![Dewey\_Finn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dewey_finn/32/4222_2.png) [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)\ **Post date:** [February 24, 2020, 2:49pm UTC](https://boards.straightdope.com/t/powdered-insoluble-fibers/848425/5 "2020-02-24T14:49:11Z")
> [@Sage\_Rat](#): > > Toss a handful of wheat at an open flame and you’ll get some singed wheat. > > Toss a handful of finely powdered flour at an open flame and fwoom. What does this have to do with digestion? You don’t have a furnace in your stomach so I think the analogy doesn’t work. ---
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [February 24, 2020, 5:28pm UTC](https://boards.straightdope.com/t/powdered-insoluble-fibers/848425/6 "2020-02-24T17:28:40Z")
> [@Dewey\_Finn](#): > > What does this have to do with digestion? You don’t have a furnace in your stomach so I think the analogy doesn’t work. Take a flawless golf ball sized salt crystal, add into a pitcher of water, start timer, stir until fully dissolved, stop timer. Take finely powdered salt of equal weight as the weight of your previous golf ball, add into a pitcher of water of equal quantity, start timer, stir until fully dissolved, stop timer. Compare times. ---
**Author:** ![Dewey\_Finn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dewey_finn/32/4222_2.png) [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)\ **Post date:** [February 24, 2020, 5:50pm UTC](https://boards.straightdope.com/t/powdered-insoluble-fibers/848425/7 "2020-02-24T17:50:29Z")
But salt is soluble in water. Try the experiment again with something insoluble in water, like a steel ball bearing and a teaspoon of finely powdered steel. What happens then? ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [February 24, 2020, 6:13pm UTC](https://boards.straightdope.com/t/powdered-insoluble-fibers/848425/8 "2020-02-24T18:13:20Z")
> [@Dewey\_Finn](#): > > What does this have to do with digestion? You don’t have a furnace in your stomach so I think the analogy doesn’t work. I didn’t take it as intending a close analogy to digestion, I took it as making a more general point that changing the physical structure of something, even if it’s the same substance, can dramatically change its properties. So we need to understand exactly what fiber is doing in digestion, and how it’s doing it. I’m certainly not an expert, but I know one relevant example. When eating “whole” foods with structurally integrated fiber, the fiber slows the digestion process, lowering the glycemic index. So that would be one situation where adding powdered fiber to processed food would probably not have the same effect on glycemic index. But there are different kinds of fiber, and I think a number of different processes, so it’s not going to be a simple answer. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [February 24, 2020, 6:21pm UTC](https://boards.straightdope.com/t/powdered-insoluble-fibers/848425/9 "2020-02-24T18:21:48Z")
> [@Broomstick](#): > > Increased surface area doesn’t change the chemistry. I know what you’re trying to say, but the terminology is not quite right - it obviously changes the _physical_ chemistry, which is always a critical aspect of biochemistry. ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [February 24, 2020, 6:33pm UTC](https://boards.straightdope.com/t/powdered-insoluble-fibers/848425/10 "2020-02-24T18:33:04Z")
> [@Dewey\_Finn](#): > > But salt is soluble in water. Try the experiment again with something insoluble in water, like a steel ball bearing and a teaspoon of finely powdered steel. What happens then? It will corrode faster. If small enough, it will suspend instead of sitting on the bottom of the beaker. And the surface area has been increased by many orders of magnitude. I’m not sure what the confusion is here. Swallow a chunk of wood and you’ll poop a chunk of wood. Swallow finely powdered wood and the cellulose and lignin will gel in your gut. I’ve already noted there’s literature about this. It seems people are posting without taking a look for themselves. ---
**Author:** ![Dewey\_Finn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dewey_finn/32/4222_2.png) [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)\ **Post date:** [February 24, 2020, 7:11pm UTC](https://boards.straightdope.com/t/powdered-insoluble-fibers/848425/11 "2020-02-24T19:11:37Z")
OK, what if it’s a pile of powdered gold vs a lump of gold? Neither will corrode, will it? And the powdered wood may gel (I have no idea if it will or not) but it won’t dissolve, will it? ---
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [February 24, 2020, 7:42pm UTC](https://boards.straightdope.com/t/powdered-insoluble-fibers/848425/12 "2020-02-24T19:42:18Z")
> [@Dewey\_Finn](#): > > But salt is soluble in water. Try the experiment again with something insoluble in water, like a steel ball bearing and a teaspoon of finely powdered steel. What happens then? Ergo, **Broomstick’s** answer was good to know. It was conceivable that cellulose was _practicably_ insoluble under traditional preparations rather than _truly_ insoluble. It is, after all, an organic molecule that is digestible by other mammals (e.g. cows). I didn’t want to take the name at face value, given that. ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [February 24, 2020, 7:54pm UTC](https://boards.straightdope.com/t/powdered-insoluble-fibers/848425/13 "2020-02-24T19:54:21Z")
> [@Dewey\_Finn](#): > > OK, what if it’s a pile of powdered gold vs a lump of gold? Neither will corrode, will it? And the powdered wood may gel (I have no idea if it will or not) but it won’t dissolve, will it? If small enough, gold will suspend (not dissolve) and look pretty. Often pink, depending on the size. A colloidal suspension can be clear (to the eye) and colorless or clear and colored. It can also be cloudy. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [February 24, 2020, 7:54pm UTC](https://boards.straightdope.com/t/powdered-insoluble-fibers/848425/14 "2020-02-24T19:54:53Z")
> [@Dewey\_Finn](#): > > OK, what if it’s a pile of powdered gold vs a lump of gold? Neither will corrode, will it? And the powdered wood may gel (I have no idea if it will or not) but it won’t dissolve, will it? I’m not sure what point you’re trying to make. The chemical reactions (or lack of them) undergone by the fiber itself are not all that matters. The nature of the physical structure formed by the fiber is important in itself; and it can certainly influence the reaction rate of anything that _is_ reactive. ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [February 24, 2020, 8:00pm UTC](https://boards.straightdope.com/t/powdered-insoluble-fibers/848425/15 "2020-02-24T20:00:54Z")
Maybe people are confused what “dissolve” means? The protein in milk is suspended, not dissolved. It is, however, digestible. > **[Solvation](https://en.m.wikipedia.org/wiki/Solvation)** > > Solvation describes the interaction of a solvent with dissolved molecules. Both ionized and uncharged molecules interact strongly with a solvent, and the strength and nature of this interaction influence many properties of the solute, including solubility, reactivity, and color, as well as influencing the properties of the solvent such as its viscosity and density. If the attractive forces between the solvent and solute particles are greater than the attractive forces holding the solute partic So... > **[Colloid](https://en.m.wikipedia.org/wiki/Colloid)** > > A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance. Some definitions specify that the particles must be dispersed in a liquid, while others extend the definition to include substances like aerosols and gels. The term colloidal suspension refers unambiguously to the overall mixture (although a narrower sense of the word suspension is distinguished from colloids by larger particle size). A colloid ha When we’re talking about insoluble fiber we typically aren’t talking about passed corn kernels, but stuff that’s too small for you to see by eye. ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [February 24, 2020, 8:05pm UTC](https://boards.straightdope.com/t/powdered-insoluble-fibers/848425/16 "2020-02-24T20:05:07Z")
> [@Riemann](#): > > I’m not sure what point you’re trying to make. The chemical reactions (or lack of them) undergone by the fiber itself are not all that matters. The nature of the physical structure formed by the fiber is important in itself; and it can certainly influence the reaction rate of anything that _is_ reactive. And lots of insoluble fiber _is_ reactive. Or at least not inert. Some is fermentable by gut flora. The surface chemistry dictates gel formation. It adsorbs other molecules. Higher surface area increases phenolic extractability and bioaccessibility, etc. ---
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [February 24, 2020, 8:12pm UTC](https://boards.straightdope.com/t/powdered-insoluble-fibers/848425/17 "2020-02-24T20:12:30Z")
> [@Ruken](#): > > Maybe people are confused what “dissolve” means? The protein in milk is suspended, not dissolved. It is, however, digestible. > [Solvation - Wikipedia](https://en.m.wikipedia.org/wiki/Solvation) > [Colloid - Wikipedia](https://en.m.wikipedia.org/wiki/Colloid) > > When we’re talking about insoluble fiber we typically aren’t talking about passed corn kernels, but stuff that’s too small for you to see by eye. For the purposes of this thread, the question is whether the fiber will continue to have its properties that allow it to act as a “fiber” rather than, e.g. being broken down into something from which energy can be extracted, fermented, etc. I’m not sure if that would be better termed “soluble”, “digestible”, or “fermentable”. I am finding a number of sources saying that cellulose is partially digested in humans. I also see one source which says that they have found greater levels of digestion (by bacteria) in direct correlation to the duration that their cellulose was reduced via ball mill. [https://www.sciencedirect.com/science/article/pii/S0022030261900510](https://www.sciencedirect.com/science/article/pii/S0022030261900510) ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [February 24, 2020, 8:43pm UTC](https://boards.straightdope.com/t/powdered-insoluble-fibers/848425/18 "2020-02-24T20:43:42Z")
> [@Sage\_Rat](#): > > For the purposes of this thread, the question is whether the fiber will continue to have its properties that allow it to act as a “fiber” rather than, e.g. being broken down into something from which energy can be extracted, fermented, etc. Per the very first response in this thread, yes. Perhaps even more so, the smaller you make it. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [February 24, 2020, 9:49pm UTC](https://boards.straightdope.com/t/powdered-insoluble-fibers/848425/19 "2020-02-24T21:49:38Z")
> [@Sage\_Rat](#): > > Ergo, **Broomstick’s** answer was good to know. > > It was conceivable that cellulose was _practicably_ insoluble under traditional preparations rather than _truly_ insoluble. It is, after all, an organic molecule that is digestible by other mammals (e.g. cows). I didn’t want to take the name at face value, given that. Cellulose is NOT digestible by cows or other ruminants. It is digestible by symbiotic bacteria that live in their guts. The cows then utilize what is essentially bacteria poop. Those same bacteria do not live in the guts of humans. Cellulose is not digestible by humans. For the record - termites can’t digest wood, either. It’s digested by symbiotic bacteria that live in their guts. Termites also live on bacteria poop. Again, that bacteria does not and can not live in human guts. ETA: OK, it’s possible for a _teeny_ bit to get broken down in a non-ruminant, non-termite gut, but I doubt very much it’s enough to matter. ---
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [February 25, 2020, 8:04pm UTC](https://boards.straightdope.com/t/powdered-insoluble-fibers/848425/20 "2020-02-25T20:04:15Z")
> [@Broomstick](#): > > Cellulose is NOT digestible by cows or other ruminants. It is digestible by symbiotic bacteria that live in their guts. The cows then utilize what is essentially bacteria poop. Those same bacteria do not live in the guts of humans. Cellulose is not digestible by humans. > > For the record - termites can’t digest wood, either. It’s digested by symbiotic bacteria that live in their guts. Termites also live on bacteria poop. Again, that bacteria does not and can not live in human guts. > > ETA: OK, it’s possible for a _teeny_ bit to get broken down in a non-ruminant, non-termite gut, but I doubt very much it’s enough to matter. Based on this study, human digestion of cellulose would seem to allow for up to 10% of it to be digested: [https://www.google.com/url?sa=t&source=web&rct=j&url=https://gut.bmj.com/content/gutjnl/25/8/805.full.pdf&ved=2ahUKEwja4quyvu3nAhWZJjQIHVh9CGoQFjAPegQIAxAE&usg=AOvVaw0ls5hSszFdyYhox3kXUc8p&cshid=1582660685594](https://www.google.com/url?sa=t&source=web&rct=j&url=https://gut.bmj.com/content/gutjnl/25/8/805.full.pdf&ved=2ahUKEwja4quyvu3nAhWZJjQIHVh9CGoQFjAPegQIAxAE&usg=AOvVaw0ls5hSszFdyYhox3kXUc8p&cshid=1582660685594) (PDF) Do you have any cites? And while, yes, it may be that it’s our gut bacteria and enzymes that perform the work, for the purposes of this thread that’s not strongly relevant. [Next page](https://boards.straightdope.com/t/powdered-insoluble-fibers/848425.md?page=2)