# Dietary fiber & processing **URL:** \ **Category:** Factual Questions\ **Created:** [March 24, 2009, 6:15pm UTC](https://boards.straightdope.com/t/dietary-fiber-processing/490612 "2009-03-24T18:15:17Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![sovtawen](https://avatars.discourse-cdn.com/v4/letter/s/7ab992/32.png) [@sovtawen](https://boards.straightdope.com/u/sovtawen)\ **Post date:** [March 24, 2009, 6:15pm UTC](https://boards.straightdope.com/t/dietary-fiber-processing/490612/1 "2009-03-24T18:15:17Z")
If I take some vegetables and blend them into a smooth liquid, am I destroying any of the fiber? Or will drinking the liquid give me the same amount of dietary fiber as eating the original vegetables? ---
**Author:** ![HumanMonkeyGod](https://avatars.discourse-cdn.com/v4/letter/h/c67d28/32.png) [@HumanMonkeyGod](https://boards.straightdope.com/u/HumanMonkeyGod)\ **Post date:** [March 24, 2009, 7:25pm UTC](https://boards.straightdope.com/t/dietary-fiber-processing/490612/2 "2009-03-24T19:25:19Z")
Liquid \<\> solid. Fiber is the part of the veg your body can’t digest, if you turn it into a liquid there’s not much to _not_ digest. ---
**Author:** ![Ferret\_Herder](https://avatars.discourse-cdn.com/v4/letter/f/e47774/32.png) [@Ferret\_Herder](https://boards.straightdope.com/u/Ferret_Herder)\ **Post date:** [March 24, 2009, 8:46pm UTC](https://boards.straightdope.com/t/dietary-fiber-processing/490612/3 "2009-03-24T20:46:06Z")
I suspect if you blend the vegetables, what you’ll really end up with is a thick paste, which will still be full of fiber. (You’d chew the veggies down into more-or-less-a-paste anyway while eating; this would just save you some effort of chewing.) If you mean that you’ll put them into a juicer, then from my understanding of how those work, you’ll lose a whole ton of fiber and only get the juice out of them. ---
**Author:** ![Bad\_Astronaut](https://avatars.discourse-cdn.com/v4/letter/b/e19adc/32.png) [@Bad\_Astronaut](https://boards.straightdope.com/u/Bad_Astronaut)\ **Post date:** [March 24, 2009, 8:56pm UTC](https://boards.straightdope.com/t/dietary-fiber-processing/490612/4 "2009-03-24T20:56:30Z")
> [@HumanMonkeyGod](#): > > Liquid \<\> solid. Fiber is the part of the veg your body can’t digest, if you turn it into a liquid there’s not much to _not_ digest. Just curious, what is the “\<\>” symbol supposed to represent? ---
**Author:** ![jayjay](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jayjay/32/6765_2.png) [@jayjay](https://boards.straightdope.com/u/jayjay)\ **Post date:** [March 24, 2009, 8:58pm UTC](https://boards.straightdope.com/t/dietary-fiber-processing/490612/5 "2009-03-24T20:58:17Z")
> [@Bad\_Astronaut](#): > > Just curious, what is the “\<\>” symbol supposed to represent? “is not the same as” ---
**Author:** ![Really\_Not\_All\_That\_Bright](https://avatars.discourse-cdn.com/v4/letter/r/e8c25b/32.png) [@Really\_Not\_All\_That\_Bright](https://boards.straightdope.com/u/Really_Not_All_That_Bright)\ **Post date:** [March 24, 2009, 8:59pm UTC](https://boards.straightdope.com/t/dietary-fiber-processing/490612/6 "2009-03-24T20:59:34Z")
> [@HumanMonkeyGod](#): > > Liquid \<\> solid. Fiber is the part of the veg your body can’t digest, if you turn it into a liquid there’s not much to _not_ digest. Your body can’t digest it because it’s cellulose, not because it’s in big pieces. As long as you blend it, instead of juicing it, you’ll get the same amount of fiber. ---
**Author:** ![Markxxx](https://avatars.discourse-cdn.com/v4/letter/m/5daacb/32.png) [@Markxxx](https://boards.straightdope.com/u/Markxxx)\ **Post date:** [March 24, 2009, 9:41pm UTC](https://boards.straightdope.com/t/dietary-fiber-processing/490612/7 "2009-03-24T21:41:38Z")
It doesn’t matter the size of the item, even with digestible foods your body breaks the food down into useable parts anyway. This is why you can have that clear bulk fiber, that doesn’t taste like anything and that isn’t gritty. (I forget the name but it’s a lot more than the Metamucil type) ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [March 24, 2009, 10:18pm UTC](https://boards.straightdope.com/t/dietary-fiber-processing/490612/8 "2009-03-24T22:18:48Z")
Some people honestly seem to believe that fiber is like a paint scraper and cleans out the insides of your intestines that way. You see statements that are the equivalent of this on way too many internet sites. Nonsense. Fiber, like every other part of food that gets put into the body, is broken down to individual molecules through the process of digestion. No mechanical action, like that of a blender, will have even the slightest effect on this. Note that commercial fiber products are usually in the form of fine powders designed to be stirred into or taken with water. Even the finest of powders is enormously huge compared to a molecule but much smaller than you’ll get from a blender. Liquid or solid, it’s exactly the same. ---
**Author:** ![toadspittle](https://avatars.discourse-cdn.com/v4/letter/t/c0e974/32.png) [@toadspittle](https://boards.straightdope.com/u/toadspittle)\ **Post date:** [March 24, 2009, 10:36pm UTC](https://boards.straightdope.com/t/dietary-fiber-processing/490612/9 "2009-03-24T22:36:47Z")
> [@Exapno\_Mapcase](#): > > Nonsense. Fiber, like every other part of food that gets put into the body, is broken down to individual molecules through the process of digestion. Not to be too crude, but that’s simply not true. I reckon everyone has had the experience of some vegetable or other passing through the digestive tract still … recognizable. Do large (i.e., not reduced to the microscopic level) pieces of indigestible plant matter have any impact on health? Does their absence? ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [March 25, 2009, 12:54am UTC](https://boards.straightdope.com/t/dietary-fiber-processing/490612/10 "2009-03-25T00:54:26Z")
Yes, a couple of hard-shelled items like peas or corn can make it through if you don’t chew them enough to break up their husks. The same is true if you swallow marbles. Big deal. That has nothing whatsoever to do with 99.9999% of digestion. ---
**Author:** ![HumanMonkeyGod](https://avatars.discourse-cdn.com/v4/letter/h/c67d28/32.png) [@HumanMonkeyGod](https://boards.straightdope.com/u/HumanMonkeyGod)\ **Post date:** [March 26, 2009, 1:34pm UTC](https://boards.straightdope.com/t/dietary-fiber-processing/490612/11 "2009-03-26T13:34:33Z")
> [@Exapno\_Mapcase](#): > > Some people honestly seem to believe that fiber is like a paint scraper and cleans out the insides of your intestines that way. You see statements that are the equivalent of this on way too many internet sites. > > Nonsense. Fiber, like every other part of food that gets put into the body, is broken down to individual molecules through the process of digestion. No mechanical action, like that of a blender, will have even the slightest effect on this. Note that commercial fiber products are usually in the form of fine powders designed to be stirred into or taken with water. Even the finest of powders is enormously huge compared to a molecule but much smaller than you’ll get from a blender. > > Liquid or solid, it’s exactly the same. Would [wikipedia](http://en.wikipedia.org/wiki/Dietary_fiber) count as one of those sites propagating the fiber falsehood? > [@wiki](#): > > Dietary fiber, sometimes called “roughage”, is the indigestible portion of plant foods that **pushes food through the digestive system** , absorbing water and easing defecation. [QUOTE=Exapno Mapcase] Fiber, like every other part of food that gets put into the body, **is broken down to individual molecules through the process of digestion**. [/quote] > [@wiki](#): > > Soluble fiber, like all fiber, **cannot be digested**. You got some resources to back up your idea that liquidized fiber will have the same effect as solid fiber? > [@Really Not All That Bright](#): > > Your body can’t digest it because it’s cellulose, not because it’s in big pieces. As long as you blend it, instead of juicing it, you’ll get the same amount of fiber. You’ll get the same amount, yes, but I don’t see how it would perform any roughage action. ---
**Author:** ![Duhkecco](https://avatars.discourse-cdn.com/v4/letter/d/8491ac/32.png) [@Duhkecco](https://boards.straightdope.com/u/Duhkecco)\ **Post date:** [March 26, 2009, 2:22pm UTC](https://boards.straightdope.com/t/dietary-fiber-processing/490612/12 "2009-03-26T14:22:00Z")
> [@Exapno\_Mapcase](#): > > Fiber, like every other part of food that gets put into the body, is broken down to individual molecules through the process of digestion. But dietary fiber, by definition, is not digested. > [@](#): > > [Harvard School of Public Health](http://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/fiber/): Officially, fiber is a type of carbohydrate that the body can’t digest. > [@](#): > > [American Heart Association](http://www.americanheart.org/presenter.jhtml?identifier=4574): Dietary fiber is the term for several materials that make up the parts of plants your body can’t digest. And, for **HumanMonkeyGod** , how does a blender make fiber digestible? **Really Not All That Bright** is right: > [@](#): > > Your body can’t digest it because it’s cellulose, not because it’s in big pieces. As long as you blend it, instead of juicing it, you’ll get the same amount of fiber. ---
**Author:** ![Philster](https://avatars.discourse-cdn.com/v4/letter/p/13edae/32.png) [@Philster](https://boards.straightdope.com/u/Philster)\ **Post date:** [March 26, 2009, 2:48pm UTC](https://boards.straightdope.com/t/dietary-fiber-processing/490612/13 "2009-03-26T14:48:26Z")
Having large pieces of food pass through your digestive track without being broken down completely (ya know, the things you recognize after you pass them) is not what fiber is all about. It isn’t about scraping your intestines clean and trying to find nature’s passable scrub brush of ruffage. **Soluble fiber** is actually getting much more broken down that insoluble fiber and the soluble fiber is more emphasized for overall nutritional health. Blendind food saves the _stomach_ some work, but as far as the intestines are concerned, the results are the same. Once blended, soluble fiber will still do valuable things like bind with fatty acids (a good thing) and the insoluble fiber will **still** act as bulk. If you take a bunch of bowling balls and grind them down into marbles, the amount of bulk is the same. No real mass is lost. If you blend down bulk food items into smaller pieces, the bulk is the same, and that bulk once broken down might be slightly easier for the _stomach_, but the good old intestines are processing the same amount of bulk, and the soluble fiber is still doing it’s thing, such as binding with fatty acids. Blend away. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [March 26, 2009, 3:31pm UTC](https://boards.straightdope.com/t/dietary-fiber-processing/490612/14 "2009-03-26T15:31:20Z")
Digestion is a process that begins in the mouth. The teeth grind the food into smaller pieces and saliva contains amylase that breaks down starches. Digestion continues in the stomach, where the hydrochloric acid component of gastric acid and the enzyme pepsin continue to break foods down. Then thousands more enzymes pour into the small intestine. If you want to play the Wikipedia game, start with the entry on [Digestion](http://en.wikipedia.org/wiki/Digestion). You’re being confused by the dual meanings of digestion. One meaning has digestion applied to the entire process of food breakdown from the mouth to the anus. The other uses digestion for the process of breaking down larger molecules into the fatty acids, simple sugars, and amino acids that can be absorbed through the lining of the small intestine. This might be better called hydrolysis, since a water molecule is needed, except that hydrolysis also has a more familiar meaning. Fiber cannot be hydrolyzed, but it certainly is broken down to component molecules. ---
**Author:** ![Philster](https://avatars.discourse-cdn.com/v4/letter/p/13edae/32.png) [@Philster](https://boards.straightdope.com/u/Philster)\ **Post date:** [March 26, 2009, 3:36pm UTC](https://boards.straightdope.com/t/dietary-fiber-processing/490612/15 "2009-03-26T15:36:10Z")
**Exapno** , who are you addressing? We are on the same page, more or less. ---
**Author:** ![HumanMonkeyGod](https://avatars.discourse-cdn.com/v4/letter/h/c67d28/32.png) [@HumanMonkeyGod](https://boards.straightdope.com/u/HumanMonkeyGod)\ **Post date:** [March 26, 2009, 8:25pm UTC](https://boards.straightdope.com/t/dietary-fiber-processing/490612/16 "2009-03-26T20:25:29Z")
I think he meant that for me. In which case my “confusion” is stemming from wiki’s and the other sources I’ve read saying, as I quoted, that fiber is not digestible. Why I would’ve been suggesting fiber cannot pass through the earlier stages of Exapno’s broader sense of the term, such as chewing, is a little unclear. > [@](#): > > how does a blender make fiber digestible? I don’t think I said it does. It doesn’t, the fiber is substance not digestible by the body… that’s what makes it fiber. I don’t wish to further confuse myself or anyone else, but I’m having trouble understanding how fiber can be broken down into molecules. Are wel talking MOLECULES, like those bubbly pics of atoms bonded togethe show usr? Or some other less chemically compounded sense? ---
**Author:** ![Really\_Not\_All\_That\_Bright](https://avatars.discourse-cdn.com/v4/letter/r/e8c25b/32.png) [@Really\_Not\_All\_That\_Bright](https://boards.straightdope.com/u/Really_Not_All_That_Bright)\ **Post date:** [March 26, 2009, 8:29pm UTC](https://boards.straightdope.com/t/dietary-fiber-processing/490612/17 "2009-03-26T20:29:29Z")
> [@HumanMonkeyGod](#): > > I don’t wish to further confuse myself or anyone else, but I’m having trouble understanding how fiber can be broken down into molecules. Are wel talking MOLECULES, like those bubbly pics of atoms bonded togethe show usr? Or some other less chemically compounded sense? **Exapno** is talking bubbly pics of atoms. The word molecule means that, and that only. However, my understanding is different from his- I was under the impression that cellulose could not be broken down down into individual molecules _or_ hydrolized. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [March 26, 2009, 10:13pm UTC](https://boards.straightdope.com/t/dietary-fiber-processing/490612/18 "2009-03-26T22:13:31Z")
Yes, I was responding to HumanMonkeyGod and Duhkecco. Cellulose molecules are long collections of thousands of glucose ring chains. Those glucose bonds are not “digestible” in that they are not hydrolyzable. In most substances they are connected by hydrogen atoms to form tiny mat-like structures. That gives fiber its roughness and durability in plants. These can still be broken down to molecular size, or glucose chains of various sizes, mechanically. I’m still not clear on how you envision the process. Do you think that fiber is simply maintained in its original form? It is obviously processed before it comes out the other end. How small do you think it gets if not molecule sized? What happens to it in a blender if you say fiber no longer works as fiber? These seem to be opposite to one another: fiber doesn’t get smaller but a blender makes it too small. What is your explanation? ---
**Author:** ![HumanMonkeyGod](https://avatars.discourse-cdn.com/v4/letter/h/c67d28/32.png) [@HumanMonkeyGod](https://boards.straightdope.com/u/HumanMonkeyGod)\ **Post date:** [March 27, 2009, 10:40am UTC](https://boards.straightdope.com/t/dietary-fiber-processing/490612/19 "2009-03-27T10:40:18Z")
> [@Exapno\_Mapcase](#): > > Do you think that fiber is simply maintained in its original form? It is obviously processed before it comes out the other end. Without conveying too much obsession with peering at my produce, I think that might’ve been the point of confusion for me - sometimes it _doesn’t_ look all that processed (i.e. recognizable), but all right 3 snooty responses later I think I get it. Blend away! [🙂](http://upload.wikimedia.org/wikipedia/commons/thumb/8/87/Cellulose-Ibeta-from-xtal-2002-CM-3D-balls.png/260px-Cellulose-Ibeta-from-xtal-2002-CM-3D-balls.png) ---
**Author:** ![Duhkecco](https://avatars.discourse-cdn.com/v4/letter/d/8491ac/32.png) [@Duhkecco](https://boards.straightdope.com/u/Duhkecco)\ **Post date:** [March 27, 2009, 11:47am UTC](https://boards.straightdope.com/t/dietary-fiber-processing/490612/20 "2009-03-27T11:47:46Z")
> [@Exapno\_Mapcase](#): > > Fiber cannot be hydrolyzed, but it certainly is broken down to component molecules. Why do you say “certainly”? Are you saying that all ingested food is broken down to component molecules? Also, what forms the bulk of human feces? Are the “component molecules” synthesized into new solids? [Next page](https://boards.straightdope.com/t/dietary-fiber-processing/490612.md?page=2)