The Problems with a High Fiber Diet

Too much fiber is a problem. Here's a simple rule for fiber.

I am not shy about elimination discussions. Having ulcerative colitis for five years will do that to a person! This disease has made me more familiar with intestines, bowels, and poop than I ever wanted to be. But on the bright side, it has led me to discover invaluable information about how to heal myself!

Irregular Bowels? Don’t reach for the Metamucil!

I’ve always tended toward constipation. Since I was eight years old, doctors have been diligently repeating their “solution” to this issue: “Eat more whole grains with fiber and take this Miralax/Senna tablets/Metamucil/Benefiber as needed.”

Unfortunately, I didn’t know that eating more whole grains is not going to help constipation–if anything, this will increase inflammation and block absorption of nutrients due to the high phytic acid content in grain fiber. I also didn’t realize that these laxitives were actually harming my intestines. For example, muscle-stimulating laxatives like Senna are actually addicting–your bowels become weakened and lazy by relying on the muscle stimulant.

Faithfully, I snacked on prunes, high fiber bread, and fiber fortified cereals. As you can imagine, I felt confused and helpless when this prescribed regimine did nothing to promote regularity. I thought I could force my damaged bowels into submission with a boatload of this undigestible material. In reality, I was irritating my intestines and filling my body with inflammatory foodscertainly not the solution for cooperative poops.

Wait… fiber is bad?!

I’m not saying all fiber is bad, but a high fiber diet, especially when the fiber comes from grains instead of vegetables, is not necessarily conducive to health. A crazy concept, I know. And just like the idea that polyunsaturated fats–not saturated fats–harm the body, this fact may take a bit of getting used to.

1. A high fiber diet throws gut flora out of whack

Consuming high doses of fiber devastates gut flora. According to Dr. Natasha Campbell McBride in The Gut and Psychology Syndrome,

“A diet high in fiber from grains (brans and breakfast cereals in particular) has a profound negative effect on the gut flora, gut health and general body metabolism, predisposing the person to IBS, bowel cancer, nutritional deficiencies, and many other problems. Fruit and vegetables provide a much better quality fiber that is not as harsh on the digestive system.”

 2. Low stomach acid + high fiber = problem

Did you know more than 90% of Americans have low stomach acid? “Wait,” you may be thinking, “how is that so when heartburn and indigestion are rampant in our society?” Our stomachs are meant to be an acid tank–a place to digest proteins and disinfect our food. When stomach acid levels drop, food is incompletely digested and this leads to bloating, gas, and heartburn. (Learn about the importance of stomach acid and how to raise stomach acid naturally.)

grainsGrain fiber contains large amounts of phytic acid, a compound which “locks” onto minerals like zinc, copper, iron and calcium. Traditional cultures practiced fermenting or soaking their grains to reduce the phytic acid and thereby making consumed minerals bioavailable. Of course, modern grain products, such as bread and cereals, are not properly prepared and contain high amounts of phytic acid.

When stomach acid is optimal, the acid helps to break down the little phytic acid and mineral bundles, rendering some of those previously stolen minerals available to the body.  But the body cannot reclaim these nutrients when stomach acid is low. Therefore, by reducing fiber and thereby reducing phytic acid intake, minerals are more efficiently absorbed. (Source)

3. “High fiber” emphasizes quantity, not quality

Is too much fiber a health hazard?The media tells us we will be sexy and healthy if we get can only down enough fiber everyday. As a result, many consumers fall prey to suave marketing and are ensnared in the quantity, not quality trap:

Copious amounts of dried prunes, slimy Metamucil, bizarre fiber bars, and fiber-fortified cereals… as long as the fiber is there, many folks don’t care about the quality of the item. Take cereals, for example. Rats fed a diet of vitamins, water and puffed wheat diet within two weeks and autopsy revealed dysfunction of the pancreas, liver and kidneys. Sally Fallon explains the results:

Results like these suggested that there was something actually very toxic in the puffed wheat itself! Proteins are very similar to certain toxins in molecular structure, and the pressure of the puffing process may produce chemical changes, which turn a nutritious grain into a poisonous substance. Source.

Processed cereal is not a nutritious substance. But that fact is oft overlooked when the consumer has the “eat all the fiber!” mindset.

4. High fiber doesn’t fix constipation

Fiber is most commonly applauded as a way to stay regular. The early studies that prompted the high fiber movement found that young, healthy study participants had better bowel movements. The participants were not constipated in the beginning. Current studies show that a high fiber diet may actually exacerbate constipation:

The role of dietary fiber to treat chronic constipation is exaggerated. A low fiber diet has been proven not to be the cause of constipation and the success of fiber intake as treatment is modest. The study reviewed conducted by Voderholzer et al showed that only 20% of slow transit patients benefited from fiber. Further data suggests that while many patients may be helped by a fiber-rich diet, some actually suffer from worse symptoms when increasing their fiber intake. (Source)

5. Health can thrive with very little fiber

The idea that humans require 30 grams of daily fiber for a long and healthy life is complete and utter gobbledygook (I love that word!). Weston A. Price, a 19th century nutrition pioneer, traveled the globe to discover the diets of thriving cultures.  Interestingly, one culture in particular thrived on virtually no fiber. This is the Masai tribe, who subsisted on the meat, milk and blood from their cattle.  They grew exceptionally tall with well-developed facial bone structure and perfect teeth.

The native Inuit also grew strong and healthy one a primarily animal-based diet of  fish, fish eggs, seal oil, caribou. This was supplemented with plant products like kelp, berries and nuts.

More Fiber Facts

Konstantin Monastyrsky’, author of the controversial book The Fiber Menace, shares more unpleasant facts about a high fiber diet on his website Here are just a few of the problems he lists with jumping on the fiber bandwagon:

  • Upon consumption, fiber produces gas, bloating, and abdominal pain due to the fermentation action of gut bacteria.
  • In the long term, it holds more dangerous consequences including constipation (yes–the opposite effect you expect), hemorrhoids, and fissures. It even contributes to the development of autoimmune diseases like Crohn’s disease and ulcerative colitis.
  • Further, studies point to the idea that a high fiber diet may increase the risk of developing both diabetes and heart disease. I surmise that this is partly due to the fact that a high fiber diet is high in grain products, which are inflammatory and wreak havoc on blood sugar balance.
  • The theory that fiber helps people loose weight by satiating appetite? Also false (according to a study at Tuft’s University). In fact, fiber has the opposite effect and actually increases appetite! Source

Soluble vs. Insoluble Fiber

Is all fiber bad? Certainly not! We do need to create a balanced fiber intake, however.

Soluble fiber, the fiber found in fruits and vegetables is much more gentle on the digestive tract. Small amounts of this fiber acts as food for the bacteria – friendly and unfriendly bugs alike – in our digestive tract and is called a prebiotic.

Insoluble fiber carries the problems discussed in this post. It is found in fiber-fortified foods, fiber supplements, and grain products like “whole grain” items, cereals, breads and pastas. The insoluble fiber content as well as other aspects make grains in general a strain on the digestive tract. All grains, but especially high fiber whole grain products, should be strictly limited (or completely avoided).

Here’s the important takeaway point from this whole post: We get all the fiber we need if we enjoy a variety of fresh fruits and veggies. If you have digestion problems, limit raw vegetables and enjoy cooked vegetables in moderation. Fiber supplements and processed whole grain foods do more harm than good.

If not fiber, then what about… you know?

Metamucil and psyllium husk should be out of the question now that we have our fiber facts straightened out. So what about addressing constipation? Believe me, I finally have this figured out! These steps WORK. Here are 5 steps to cure constipation naturally.

Too much fiber is a problem. Here's a simple rule for fiber.

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  1. HopeSimmons says

    There are no words to describe how happy and excited I am for This post later!!! Thank you thank you thank you!!! I am tired of being the only 15year old I know living like a weirdo on this diet and an old lady who can’t poop!! Yay!!

    • says

      We wierdos will unite! People who take good pooping for granted just don’t understand that constipation is so difficult. I’m so glad that the following post will help you!

  2. JamieSchull says

    I took citracel for a year in my twenties so I could get “enough” fiber as I had crazy digestive problems, a few years later I was diagnosed with Celiac stopped the gluten 2 1/2 years ago and I feel fabulous. By the way I am Fiber obsessed in a different way, wool. alpaca, cotton, angora, cashmere :) I love to spin my own yarn and knit everyday, I guess that’s the good fiber obsession. Thanks for the great article.

  3. says

    GREAT resource!! Thanks for linking up at our Gluten Free Fridays party last week! I have tweeted and pinned your entry to our Gluten Free Fridays board on Pinterest! :) I hope that you’ll join us this week to share more yummies! Also, be sure to stop back by to see who the winner of the Planet Rice will be! The winner will be announced at GFF #9 Cindy from

  4. says

    Fiber kills me. It kills me. I don’t eat wheat, gluten, soy, grains, etc… But I do eat vegetables, and yes, they kill me too in large quantities but SADLY I am a HUGE EATER… So huge portions are my life. Eating massive quantities of protein = I am perfectly fine… Mass amounts of veggies and I have to go to the hospital and get my stomach pumped.

    I actually do not have a large intestine – it was taken out about 4 years ago because I had a cecal volvulos- while the doctor isn’t sure why, I believe it was probably from TOO MUCH fiber!

  5. says

    What a terrific, well-articulated article, Lauren! It’s great to see someone speaking out about how a high fiber diet (esp. in the form of grains) can really reek havoc on the GI tract. When I was diagnosed with IBS, I was told to eat more fiber, which was ridiculous because it only exacerbated my symptoms. I found that limiting my intake of fiber by reducing grains and concentrating on gut-healing foods like bone broths, healthy fats and cultured foods really helped me to overcome this condition without the use of medications, praise be to God! Blessings in Christ, Kelly

  6. Mark says

    I’m on Paleo (no dairy, no grain). Eat a lot of veggies, some berries (I’m diabetic and have RA as well). Have had intermittent constipation issues over past 40 years. I use coconut oil in my smoothies in the morning. Also coconut kefir and Jarrow probiotics. I take 2 heaping teaspoons of Calm at night, but am still having a problem getting regular. Occasionally would add chia seeds or ground flax seed to smoothies, but that didn’t seem to help. Haven’t gone the enema route. Drinking more water doesn’t really seem to help. Eat grass fed meets, pastured poultry, pastured eggs. Am on Enbrel and small dose of methotrexate for my RA (which I’ve had 14 years). Started paleo seriously about 6 months ago. Any other suggestions you might have? I was thinking the probiotics and Calm would do the trick, but not helping much.

  7. says

    I did want to mention something about Westin Price. I am currently trying to follow his plan, for the most part. However, just because certain indigineous tribes lived well on a certain diet, doesn’t mean we can too. For example, I had a client in once who worked a lot with the First Nations people we have here in Canada. They actually lack the gene to metabolize alcohol. So, when they drink it, they develop an allergic reaction to it, and they can become addicted, even though it completely ruins them. (turning red means you’re allergic by the way) He also explained to me how different cultures have different responses to different foods. Like wine in Italy. The Italians have lived and thrived on wine for thousands of years. Their bodies have become adapted to it and its like water to them. The Mexicans thrive on corn and masa….their bodies love it and it is easily assimilated and digested. I can’t eat corn. My body completely refuses it, and of course its my favourite food. As is the way. I can’t drink red wine either….any kind of red wine. I have no Italian in my blood. I think one needs to be careful when comparing cultures. This is why they always say to eat food locally sourced, as it contains what your body really needs for the person who lives in that locale.

    • says

      I agree with you 100%! The reason I brought up the traditional cultures and fiber is that many of the tribes in his book at a relatively low fiber diet (at least low compared to our 30+ grams a day recommendation). But yes, I completely agree that we have different metabolisms based on our unique hereditary/cultural backgrounds.

      • Ray says

        I would agree with you. Look at the Hunza tribes in South Asia. They eat what grows on the earth and have exceeded all tribal groups in terms of their longevity. They are not eating processed foods.

        I do think that the vegetables and fruit that are provided in US big chain grocery stores are stored with pesticides and this has been the history in the US. This has contributed to many health isssues in the US and specifically the imbalance of digestion and why its just a prevasive problem in the United States. We are being charged high prices for “organic” non-pesticide food for food that is just grown in the earth..

  8. Lisa says

    I had no idea. Although I will say I had a suspension and this article was right on the money with my gut intuition (pun intended!). I eat Quest Bars religiously and I am curious to know, should I ween off of these fiber filled protein packed treats?

  9. Leticia says

    What about consuming leafy greens, other veggies and legumes that are high in fiber? Does this apply?
    Or is this all about fiber from grains?

  10. Ray says

    have been eating cereals for this new diet and since then I have had constipation and so so much gas. I could not figure out the problem. I now know what the issue is.

    Why do US websites post erroneous information that fiber is required in your diet. I did buy fiber gummy worms as a result of reading those articles.

    I was recently in Asia and just fine because I was eating fresh foods. I am going to return the gummy worms and stop eating the cereal.

    Thank you again!

  11. Ray says

    Also, I forgot to state, that the diet I am is Jenny Craig. I asked them whether this was all processed foods and they said no, its real food. I don’t think so.. This is why I have so much gas.

    I have read other blogs on Jenny Craig foods and they do cause a lot of gas. Other women have complained as well..

    Why do US companies do that and lie to consumers? This messed me up. Thank god. I have the wisdom to figure this out and quit eating this crap..
    Thank you!

  12. Kathy Potter says

    I’ve always thought there was something wrong with the fact that my doctor kept pushing fiber on me. I’ve had multiple surgeries (colon resections) and had to learn how to ‘manage my poop’ on my own by throwing out what the doctors told me and starting over. Great article!!!

  13. joanna says

    great post although i think you should stress that fruit/veggie fiber can be just as bad as grains. i was diagnosed with ulcerative colitis after my stint as a raw fruit vegan. i 1000000% blame it on all the fiber i was ingesting and now i can’t reverse the damage.

  14. Ashley says

    Hi Lauren, I’ve been reading through all of your post and agree with many things you discuss. However, I was vegan for 5 years and my digestion was better in those five years than it has ever been in my life. I got tired of beans and rice and more beans and rice. So I quit the vegan diet. I have been eating organic since I was 10, thankfully my mother caught on and being in the Pacific Northwest, organic eating was no issue. Since introducing meat and eggs and very limited dairy into my diet my body is NOT happy. I don’t have the quality digestion I had when I was vegan. I take probiotics and buy all my food from PCC. I have acne all over my face and other parts as well. I don’t understand what the issue is. I know you’ve been to Seattle, do you recommend anyone in the area that would be worth seeing? Thank you :)


  15. Mike says

    I agree that it’s important not to go overboard on grains of any kind, even the whole wheat variety. I however, could not go without my prunes and Fiber One bars and bread, they are delicious, filling and work for me. Being a 22 year old male in a wheelchair, I lost a great deal of weight and never used to have a diet including fiber until recent years with the weight loss. If I was fortunate I would go to the restroom with at least minimal difficult every other day, Fiber, mainly from fruits and vegetables keep me on a daily schedule now for the most part, and I could never give up the stuff,

  16. Conor says

    Hi Lauren, how much fibre would you recommend? I’m completely grain and starch free (scd) but by the time I’ve had one avocado and a portion or two of vegetables I’m already over what you’re saying is too high. This would seem to restrict the diet even further and I’m not sure what to eat anymore seeing as I need to gain weight significantly.

  17. TF says

    Such a great article. I have suffered from constipation for years. In my teens and early 20s I was lucky if I went once a week. Things got better briefly in my late 20s but then in my 30s, I suffered from terrible IBS-C and was advised to increase fiber, decrease meat, go vegetarian, go vegan… all those things made me so much worse. Now I am in my 40s, Paleo plus potatoes for 3 years now. But I think the damage is done. I think I have a motility disorder now. Tomorrow I have an upper endo and colonoscopy to check for UC due to recent changes in my symptoms. I have a friend with gastroparesis who is teaching me that even all that cooked veggie fiber I have been eating on Paleo may be too much. I’m learning to cut down and eat veg that are very well-cooked and that have less fiber to begin with. I just wanted to say, out of all the nutrition bloggers out there, I really value your info the most. It seems to go along more with what makes intuitive sense to me than any other. I hope after you get done at Bastyr you write a book!

  18. K. says

    Great article. I suspect this is what is giving me bad gas and bloating. I’ve recently been consuming alot of coconut flour and snacking on flax seed.

    What is your take on coconut flour and flax seed?

  19. Norm and Marg Shaw says

    We would be interested in your comments regarding sour dough bread. My wife thinks your background is Armenian but don’t feel you have to answer her. A really down to earth common sense attitude on how to live simply and healthy. Congratulations. Norm

  20. NC says

    Thank you for this! Yes, the fiber worship has to stop. I was once a believer but I have permanent intestinal damage to show for my gullibility..

    I began with constipation issues in my early 40s, despite a diet rich in fruits and vegs. I complied with my doctors’ advice to add fiber in the form of psyllium husk and I became a vegetarian. Over the years I got worse, I changed doctors, but I kept getting the same advice. I got worse yet. The last doctor added Miralax and I dutifully took it for six weeks despite feeling the worst I have ever felt. At that point I was up to 60-65 grams of fiber a day, still constipated, but now I had prolapsing hemorrhoids, copious bleeding, bloating, gas and belly noises that would stop a conversation at work.. I have had two colonoscopies and three hemorrhoid ligations.. Along the way I developed excruciating muscle cramps in my legs, feet and abdominal muscles and a heart arrhythmia, which are likely due to imbalance of calcium, magnesium and potassium, due to the damage done by the pressure of all that fiber.

    I now have severe diverticulosis and frequent diverticulitis, as well as tubular adenoma polyps, all of which are supposedly should have been prevented by a lifetime of high fiber. As the years went on my ability to tolerate fiber plummeted. Now, I can’t so much as eat a salad without copious bleeding, bloating and nausea. I finally found a well-known specialist who told me to get off the fiber and gas-producing foods and I feel better now than I have in decades but much of the damage is permanent.

    I write this hoping to raise the alarm so that others won’t fall into this trap. The fiber worship has to stop; there is no science behind it and yet the vast majority of doctors, nurses and nutritionists will urge it on you. Try it if you wish, but if it doesn’t help, STOP! No matter what the doctor says, just stop.

  21. Ruth says

    Hi. I just subscribed and am waiting for my confirmation email.:). This post really hits home. I have tried everything for regularity. Stool softeners, fiber bars, wheat. I actually got better once I quit eating wheat. Water, as I am learning, is not helping either.
    I am looking all over your site and it is very good.

  22. Maggie King says

    Thank you for sharing your knowledge on this topic. I have had chronic constipation for about 10 years and took Miralax religiously for about nine years. I remember asking my doctor at the time if it was safe to take Miralax daily, and she said yes, that it would not be habit forming.

    When the Miralax stopped working by itself, I added psyllium husk to my regimen. ( I did this this combo for about one to one and a half years).

    The last 6-8 months I noticed that I would wake up very swollen. My eyes were very puffy as well as my hands. I could not understand why. I would at times weigh 3-4 pounds heavier over night. This was really scary, as I thought I had some sort of illness going on. I went to my doctor and had blood tests done, the results were normal. She had no idea, about the swelling, but ordered a colonoscopy.

    I stopped the Miralax and the psyllium husk about two weeks prior to the colonoscopy, on my own, and noticed that I stopped waking up puffy or swollen. After my colonoscopy I was told that the Miralax had caused brown spots in my colon, and that this could not be reversed; I was told that I should have never taken it daily especially for that long.

    I changed from the Miralax to Gentle Fibers by Jarrow Formulas, which I bought at Clarks, health store. It did what it is meant to do within a couple of hours of taking it. I have been taking it for almost one month, and I’m afraid that it will cause water retention as well or that it might harm me over time.

    I would appreciate any feedback on the side effects of long term use on the Gentle Fibers. Thank you!! MK.

  23. Diane says

    Please clear up my doubt, very important to me. Hello Lauren I love your posts and this blog, I know that your intention is not to force any ideas on anyone, and I have been cutting down on fibre and have seen some symptoms get better. But I have a confusion, because one of the things I stopped eating is brown rice, and I saw on a post that you advised to not eat brown rice because of the large fibre content, that it was better to eat normal white rice or even better quinoa, but then doing some research I found that in one cup of brown rice there was 3.5 grams of dietary fibre while in one cup of quinoa theres 12 grams. So did you not know this, or why do you say quinoa is better?

  24. Mary says

    I’ve had ulcerative colitis for years. Diagnosed in 1996, but suffered quite a few years before they finally decided to investigate. I’ve had periods of remission, but since 2010, I’m on a twice-week maintenance of what I call my “mousse” medication (up the back door lol).

    4 days ago, after the worst night I’ve ever had with colitis, decided to put myself on a low fiber diet. Not recommended (apparently) long term, but the change has been dramatic. It’s a diet totally opposite to what I normally have (beans, brown rice, vegetables, oats – nothing raw though as I can’t tolerate that, but used to have it a lot).

    I’m convinced now that the years I spent dutifully swallowing the intestinal equivalent of sandpaper have contributed to the colitis.

    I’m 4 days into this diet now, and will remain on it for 6 weeks or so (as advised by the doctor).

    It’s fine though – I like white bread and saltines! Yum!

  25. Sasha says

    Dear Lauren thank you for always brining important info. I suffer recently from severe bloating since i am baking coconut flour bread with psyllium husk powder ? Also i like quest bars?

    Are they all harmfull? Should i stop them all ? Or is coconut flour ok since i am on paleo diet ?

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