# High-fiber diet ("Good For You") vs. plain old regular pooping vs. diarrhea. Why is fiber special? **URL:** \ **Category:** Factual Questions\ **Created:** [June 29, 2013, 2:42am UTC](https://boards.straightdope.com/t/high-fiber-diet-good-for-you-vs-plain-old-regular-pooping-vs-diarrhea-why-is-fiber-special/662181 "2013-06-29T02:42:14Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [June 29, 2013, 2:42am UTC](https://boards.straightdope.com/t/high-fiber-diet-good-for-you-vs-plain-old-regular-pooping-vs-diarrhea-why-is-fiber-special/662181/1 "2013-06-29T02:42:14Z")
See subject. Now, I know diarrhea is bad for lots of reasons, I think primarily (as a sympton in itself) because of the risk of dehydration and, I think but am less sure, of malnutrition in general. But I’m working backward here on situations of pooping. (If anyone can phrase that more coherently I’d be pleased to read it.:)) So, my endocrinologist told me to do the daily Metamucil or any other fiber and water thing. I bought some psyllium, thrown in half a lemon and Splenda, and I’m good to go. So I poop. I pooped fine–regelah, as they say–before. The label even says to keep taking it until “regularity” returns. I’m not worried I’m going to die or anything, nor is my life and its style particularly changed. I know fiber fills you up, makes you feel sated, etc. But why is it recommended for anything but constipation? What’s the big deal? I asked my endo, but he was typically and annoyingly Delphic about the whole thing. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [June 29, 2013, 3:36am UTC](https://boards.straightdope.com/t/high-fiber-diet-good-for-you-vs-plain-old-regular-pooping-vs-diarrhea-why-is-fiber-special/662181/2 "2013-06-29T03:36:37Z")
Feeds the good bacteria which produce all sorts of good messengers active both local to the gut and in a variety of distant locations in the body up through the brain. Best of course to have a variety of fiber sorts from a variety of high fiber foods, including real veggies and fruits. _May_ decrease rate of [colon cancer](http://www.webmd.com/diet/fiber-health-benefits-11/fiber-cancer). ---
**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:** [June 29, 2013, 3:42am UTC](https://boards.straightdope.com/t/high-fiber-diet-good-for-you-vs-plain-old-regular-pooping-vs-diarrhea-why-is-fiber-special/662181/3 "2013-06-29T03:42:10Z")
The digestive tract does two things: it breaks food down to extract all possible food value from it and it absorbs water, both from liquids and from within solid foods. We don’t think about the latter when it works but we suffer when it fails to balance out properly. Too much water leaves and the result is constipation and hard stools; too little water leaves and the result is diarrhea and loose stools. People with either one long for the other but neither is at all good for you. Fiber as a term covers a lot of ground, but assume I’m talking about the right kind of fiber here. Its best feature is that it absorbs water. If you have too little water in your intestines, the fiber soaks up what’s there and helps push the stools out, which are softer and don’t hurt as much. And you definitely don’t ever want impacted stool, because that’ll send you to a hospital doubled over in pain. If you have too much water in your intestines, the fiber soaks it up and adds bulk and solidity to your stools. Too much water works on your rectum like a flood eroding the riverbanks. Dehydration is usually not the main problem, except when diseases are involved. Fiber is definitely recommended for more than just constipation. Fiber is a balancer. Regularity is marketing buzzword but it’s want you desperately want and a fantastic relief when you have it. It doesn’t sound like you’ve had a real need for fiber before, which you should be thankful for. Fiber has other benefits that are being better studied today, but that doesn’t sound like what you’re asking about. ---
**Author:** ![Roderick\_Femm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/roderick_femm/32/14875_2.png) [@Roderick\_Femm](https://boards.straightdope.com/u/Roderick_Femm)\ **Post date:** [June 29, 2013, 6:11am UTC](https://boards.straightdope.com/t/high-fiber-diet-good-for-you-vs-plain-old-regular-pooping-vs-diarrhea-why-is-fiber-special/662181/4 "2013-06-29T06:11:43Z")
Do these benefits (that **Exapno** describes so clearly) vary if the fiber is soluble or non-soluble? I keep hearing that a lot of the “fiber” in “high fiber” manufactured foods (as distinct from fruits and vegetables as nature made 'em) is non-soluble and therefore of limited utility; presumably that means that it might help push out the stools just from the volume, but it wouldn’t regularize the fluids. Yes? Roddy ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [June 29, 2013, 6:27am UTC](https://boards.straightdope.com/t/high-fiber-diet-good-for-you-vs-plain-old-regular-pooping-vs-diarrhea-why-is-fiber-special/662181/5 "2013-06-29T06:27:44Z")
> [@Roderick\_Femm](#): > > Do these benefits (that **Exapno** describes so clearly) vary if the fiber is soluble or non-soluble? I keep hearing that a lot of the “fiber” in “high fiber” manufactured foods (as distinct from fruits and vegetables as nature made 'em) is non-soluble and therefore of limited utility; presumably that means that it might help push out the stools just from the volume, but it wouldn’t regularize the fluids. Maybe soluble fiber has some benefit, but I don’t think that can be it. Just because some fiber is insoluble, it does not follow that it cannot absorb water. In fact, I am pretty sure it is going to. Solubility and absorbency are not the same thing. ---
**Author:** ![Nava](https://avatars.discourse-cdn.com/v4/letter/n/da6949/32.png) [@Nava](https://boards.straightdope.com/u/Nava)\ **Post date:** [June 29, 2013, 7:40am UTC](https://boards.straightdope.com/t/high-fiber-diet-good-for-you-vs-plain-old-regular-pooping-vs-diarrhea-why-is-fiber-special/662181/6 "2013-06-29T07:40:20Z")
Fiber is part of the system that helps the process stay regular, but it doesn’t have to be from supplements; if you were having troubles (the OP is coy enough to count as Victorian), then fiber and yoghurt (or biotics in capsules) are part of the recommended course to re-regularize things. I’ve met people who were surprised when others would say “ah yes, so the doc prescribed you fiber and yoghurt?” “Uh? No, he just prescribed this fiber thing and said to have it with my yoghurt.” “_stares_” “:smack:” Her doctor tried to put my mother on calcium supplements because women in her age group often show signs of decalcification. She said, since there are tests for that, how about running some before we add another pill to the box? He said, oh women your age are always decalcified. She said well, my mother has 27 years on me and bones you could use to build houses with, so test me. The test showed my mother has no calcium deficiency: no calcium supplements for her. But she had to fight it. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [June 29, 2013, 7:59am UTC](https://boards.straightdope.com/t/high-fiber-diet-good-for-you-vs-plain-old-regular-pooping-vs-diarrhea-why-is-fiber-special/662181/7 "2013-06-29T07:59:44Z")
Moi? Coy? If they were passing out TMI awards…(there’s a few MPSIMS’s out there that would curl your toes). Hey, I already said I was regelah. Plus I Don’t Strain, which ranked just below Thou Shalt Have No Other God Before Me when I was growing up. That and that eating/ swimming thing. That’s exactly my point (which I see was addressed above–thanks to all, BTW): why would a “high-fiber” diet do anything more or less than keep your crapping schedule on the up and up, which people have recognized since the year -0 as being good for health. My guy mentioned it relative to, I think, my lipid scores, which were off the chart. ---
**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:** [June 29, 2013, 8:32am UTC](https://boards.straightdope.com/t/high-fiber-diet-good-for-you-vs-plain-old-regular-pooping-vs-diarrhea-why-is-fiber-special/662181/8 "2013-06-29T08:32:55Z")
Soluble fiber is believed to have some ability to lower cholesterol and lipids, presumably by preventing them from being absorbed in the first place. ---
**Author:** ![jtur88](https://avatars.discourse-cdn.com/v4/letter/j/e9c0ed/32.png) [@jtur88](https://boards.straightdope.com/u/jtur88)\ **Post date:** [June 29, 2013, 12:58pm UTC](https://boards.straightdope.com/t/high-fiber-diet-good-for-you-vs-plain-old-regular-pooping-vs-diarrhea-why-is-fiber-special/662181/9 "2013-06-29T12:58:43Z")
Most of the fiber content in the foods normally eaten are in the parts that are discarded in processing. The husk of wheat and grains, the peelings of fruits and vegetables, etc. So since the advent of highly-processed foods, most of the fiber has been removed from your food, and fed instead to pigs at the hog farm down the road, whose owner has a deal with General Mills. Hogs, apparently, never get constipated. because they are getting all the fiber that fosters regular pooping in herbivores… Plain old regular pooping was done by your grandparents under the aegis of a diet that contained the high fiber parts of the foods. ---
**Author:** ![Attack\_from\_the\_3rd\_dimension](https://avatars.discourse-cdn.com/v4/letter/a/b38774/32.png) [@Attack\_from\_the\_3rd\_dimension](https://boards.straightdope.com/u/Attack_from_the_3rd_dimension)\ **Post date:** [June 29, 2013, 1:56pm UTC](https://boards.straightdope.com/t/high-fiber-diet-good-for-you-vs-plain-old-regular-pooping-vs-diarrhea-why-is-fiber-special/662181/10 "2013-06-29T13:56:04Z")
> [@Broomstick](#): > > Soluble fiber is believed to have some ability to lower cholesterol and lipids, presumably by preventing them from being absorbed in the first place. I think the theory is: Cholesterol is used to make bile. Bile binds soluble fiber. Bile+fiber gets pooped out of your body. Your body makes more bile from cholesterol, rinse, repeat and tah dah, You’ve lowered your blood cholesterol. Here’s a [weak cite](http://www.ext.colostate.edu/pubs/foodnut/09333.html), I can look for something more authoritative if you want. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [June 29, 2013, 4:36pm UTC](https://boards.straightdope.com/t/high-fiber-diet-good-for-you-vs-plain-old-regular-pooping-vs-diarrhea-why-is-fiber-special/662181/11 "2013-06-29T16:36:42Z")
Aah. Now it starts to make sense. Thanks. > [@jtur88](#): > > …Plain old regular pooping was done by your grandparents… I could’ve done without this particular image. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [June 29, 2013, 5:48pm UTC](https://boards.straightdope.com/t/high-fiber-diet-good-for-you-vs-plain-old-regular-pooping-vs-diarrhea-why-is-fiber-special/662181/12 "2013-06-29T17:48:30Z")
The important feature of fiber is that it prevents colon cancer. There may be several reasons for this, but the simple one is that it mechanically cleans the walls of the colon. ---
**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:** [June 29, 2013, 6:55pm UTC](https://boards.straightdope.com/t/high-fiber-diet-good-for-you-vs-plain-old-regular-pooping-vs-diarrhea-why-is-fiber-special/662181/13 "2013-06-29T18:55:18Z")
> [@TriPolar](#): > > The important feature of fiber is that it prevents colon cancer. There may be several reasons for this, but the simple one is that it mechanically cleans the walls of the colon. This is way, way overstated at best and flat-out wrong at worst. Here’s what the [Harvard School of Public Health](http://www.hsph.harvard.edu/nutritionsource/fiber-and-colon-cancer/) has to say on the subject. > [@](#): > > When studies that can take such things into account on an individual level began to look at the issue of fiber and colon cancer, the picture became much less clear. A number of case-control studies found that a high fiber intake was linked to a lower risk of colon cancer, but many did not. Given these wavering results—and because case-control studies are not an optimal way to assess food intake, relying as they do on participants’ recollections of what they ate in the past—more research using better methods was needed. In the meantime, many health professionals still regularly recommended a high fiber intake for people trying to lower their risk of colon cancer. > > Not until the results of cohort studies came out did this recommendation begin to lose its backing. Because cohort studies observe a group of people over time, their findings are generally stronger than those of case-control studies, especially when it comes to something like diet and colon cancer. What most of these cohort studies found was that fiber intake had very little, if any, link with colon cancer. A more detailed summary of studies can be found on the National Cancer Institute’s [Colorectal Cancer Prevention page](http://www.cancer.gov/cancertopics/pdq/prevention/colorectal/HealthProfessional/page3). It also starts out “The evidence on whether dietary fiber exerts a protective role in reducing the incidence of CRC is mixed.” Check the section labeled “Dietary fiber, vegetables, and fruit” for more. ---
**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\ **Post date:** [June 29, 2013, 7:14pm UTC](https://boards.straightdope.com/t/high-fiber-diet-good-for-you-vs-plain-old-regular-pooping-vs-diarrhea-why-is-fiber-special/662181/14 "2013-06-29T19:14:08Z")
> [@Attack\_from\_the\_3rd\_dimension](#): > > I think the theory is: > > Cholesterol is used to make bile. > Bile binds soluble fiber. > Bile+fiber gets pooped out of your body. Your body makes more bile from cholesterol, rinse, repeat and tah dah, > You’ve lowered your blood cholesterol. > > Here’s a [weak cite](http://www.ext.colostate.edu/pubs/foodnut/09333.html), I can look for something more authoritative if you want. Ooh… OOOOOOHHHH!!! This just made my own personal belly tortures make more sense. I think my gallbladder’s angry lately, and remembering to take all my daily fiber doses (I usually do 3 psyllium and 3 doses of soluble gummies) really helps. Days when I get sloppy and lazy, I get belly pains, even though I’m pooping okay. I bet I’m setting my bile production on high with all that fiber, and need to take my fiber regularly (no pun intended) to bind it up or the bile starts to irritate things. ---
**Author:** ![fumster](https://avatars.discourse-cdn.com/v4/letter/f/e9c0ed/32.png) [@fumster](https://boards.straightdope.com/u/fumster)\ **Post date:** [June 29, 2013, 7:28pm UTC](https://boards.straightdope.com/t/high-fiber-diet-good-for-you-vs-plain-old-regular-pooping-vs-diarrhea-why-is-fiber-special/662181/15 "2013-06-29T19:28:49Z")
> [@jtur88](#): > > Plain old regular pooping was done by your grandparents under the aegis of a diet that contained the high fiber parts of the foods. Oh please. White flour and white rice have been around for hundreds of years. Kellogg and Graham were contemporaries with my grandfather and they were trying to add more fiber 100 years ago. My grandfather ate less fiber than I do because vegetables and fruits were harder to get year round. My great Aunt used senna pods to stay regular. People of his age peeled their vegetables. It was hippies in the US that stopped doing that. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [June 29, 2013, 7:58pm UTC](https://boards.straightdope.com/t/high-fiber-diet-good-for-you-vs-plain-old-regular-pooping-vs-diarrhea-why-is-fiber-special/662181/16 "2013-06-29T19:58:35Z")
> [@Exapno\_Mapcase](#): > > This is way, way overstated at best and flat-out wrong at worst. Here’s what the [Harvard School of Public Health](http://www.hsph.harvard.edu/nutritionsource/fiber-and-colon-cancer/) has to say on the subject. > A more detailed summary of studies can be found on the National Cancer Institute’s [Colorectal Cancer Prevention page](http://www.cancer.gov/cancertopics/pdq/prevention/colorectal/HealthProfessional/page3). It also starts out “The evidence on whether dietary fiber exerts a protective role in reducing the incidence of CRC is mixed.” Check the section labeled “Dietary fiber, vegetables, and fruit” for more. Well then, I’m wrong. I guess I’m just not up to date on this. Even though there were known to be a lot of factors in involved earlier, high fiber was proclaimed a positive factor in decreasing risk of cancer. I guess it’s now down to a minor factor at best. There are still counter arguments, but your cites indicate they aren’t holding up after more thorough analysis. ---
**Author:** ![Chief\_Pedant](https://avatars.discourse-cdn.com/v4/letter/c/a6a055/32.png) [@Chief\_Pedant](https://boards.straightdope.com/u/Chief_Pedant)\ **Post date:** [June 29, 2013, 8:55pm UTC](https://boards.straightdope.com/t/high-fiber-diet-good-for-you-vs-plain-old-regular-pooping-vs-diarrhea-why-is-fiber-special/662181/17 "2013-06-29T20:55:05Z")
It was Denis Burkitt (the same guy for whom a type of lymphoma is named) who is most responsible for advancing the notion of the importance of dietary fiber in modern western culture. (“fibre,” for Dr Burkitt. His was a conclusion based on his observation of the difference between Western and African stool habits and the frequency of colon cancer (as I recall). Subsequent studies minimize the cancer connection, although perhaps vascular and diabetes benefits are real–related in turn to fat and carbohydrate handling in the presence of fiber. It’s tricky to sort out. Maybe a high-fiber diet just tends to be a low-sugar/fat/calorie diet. Not the same thing as fiber per se being beneficial. Denis was a hoot at lectures when he was preaching his passion for fiber. On a lecture tour to the US, he told our med school class we should be all be taking “stool breaks” as often as pee breaks and was very enthusiastic about encouraging large soft stools. Note that these sorts of stools are not “diarrhea.” We’re talking toothpaste here; not liquid. It does seem intuitive that people who are full of fetid, old, dried-up “toxin-filled” crap aren’t as healthy as people who drop a large family off at the pool every morning and start the day with a lovely clean colon, but maybe I’ve just been swayed by too many infomercials from that bowel-cleansing guy. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [June 29, 2013, 11:06pm UTC](https://boards.straightdope.com/t/high-fiber-diet-good-for-you-vs-plain-old-regular-pooping-vs-diarrhea-why-is-fiber-special/662181/18 "2013-06-29T23:06:03Z")
Fiber has to with a lot of shit other than shit. CP referenced the diabetes connection - [an interesting study](http://care.diabetesjournals.org/content/29/4/775.full) relevant to that. Insoluble fiber supplementation increased insulin sensitivity. > [@](#): > > Cereal fiber consumption is linked to a reduced risk of type 2 diabetes and cardiovascular disease in prospective cohort studies. Notably, associations between cereal fiber intake and reduced diabetes risk remain significant after correction for confounding factors, e.g., changes in body weight, age, exercise, intake of fat, smoking, alcohol intake, or a family history of diabetes (16). To date, no obvious mechanisms for the beneficial effects of cereal fibers have been described. Based on recent findings by our group (8), we hypothesized that consumption of purified insoluble fiber, which is the predominant fraction of cereal fiber, might improve whole-body insulin sensitivity. Here we show that an intake of insoluble dietary fiber within the recommended daily range (10) for a time period as short as 3 days significantly improved whole-body insulin sensitivity in overweight and obese women … Again however it must be emphasized: fiber is not one thing, it is a collection of substances. A variety of high fiber real foods is clearly the best package, both for health and for tasty eating! ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [June 30, 2013, 1:39am UTC](https://boards.straightdope.com/t/high-fiber-diet-good-for-you-vs-plain-old-regular-pooping-vs-diarrhea-why-is-fiber-special/662181/19 "2013-06-30T01:39:34Z")
OP here. What I should have said in addition is that I have raging diabetes. **DSeid** ’s contribution is important. Money quote: …we show that an intake of insoluble dietary fiber within the recommended daily range (10) for a time period as short as 3 days significantly improved whole-body insulin sensitivity in overweight and obese women, as assessed by the euglycemic-hyperinsulinemic clamp. Insulin sensitivity was improved by 13% in those subjects, who were likely to have ingested the test meals, and this effect was attenuated, but still significant, when results for all subjects were analyzed. Notably, the magnitude of pharmacological improvement in insulin-stimulated glucose metabolism after a 3-month treatment with the insulin-sensitizing drug rosiglitazone was between 20 and 68%, depending on the administered doses of insulin during the clamp and with the most pronounced effect using relatively low insulin doses (120 vs. 20 mU/m2 per min) (17). Potential molecular mechanisms leading to improved insulin sensitivity remain unexplained by the current study. However, the presented data clearly indicate that insoluble fibers, containing mainly cellulose and hemicellulose, are unlikely to be physiologically inert and may be interesting candidates for future research. We have previously shown that the insoluble fiber used in our experiments is unlikely to influence macronutrient absorption or gastric emptying (8), which is in accordance with the literature (2). An increased magnesium intake has been shown to improve insulin sensitivity (18). However, magnesium contents of the test meals in the current study were virtually identical, and serum magnesium concentrations were unchanged by fiber intake. No effect of fiber intake on blood lipids, serum ghrelin, or serum adiponectin concentrations (19) could be detected as other possible drivers that might have influenced insulin sensitivity. And they don’t have a clue why. Note last sentence as well. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [June 30, 2013, 1:40am UTC](https://boards.straightdope.com/t/high-fiber-diet-good-for-you-vs-plain-old-regular-pooping-vs-diarrhea-why-is-fiber-special/662181/20 "2013-06-30T01:40:39Z")
> [@TriPolar](#): > > Well then, I’m wrong. I guess I’m just not up to date on this. Even though there were known to be a lot of factors in involved earlier, high fiber was proclaimed a positive factor in decreasing risk of cancer. I guess it’s now down to a minor factor at best. There are still counter arguments, but your cites indicate they aren’t holding up after more thorough analysis. Also: **Tripolar** , it’s comments like this that keeps the tone way too civil here. Knock it off! [Next page](https://boards.straightdope.com/t/high-fiber-diet-good-for-you-vs-plain-old-regular-pooping-vs-diarrhea-why-is-fiber-special/662181.md?page=2)