Nov 022011

This article really opened my eyes to a few things about fiber and IBS. If you are considering being vegan, or are a vegan, and have IBS you really should read this.

Article Source:


Irritable Bowel Syndrome?
Q&A with Bill Harris, M.D.

Q. I’ve been a vegan since i was 12 and a vegetarian ever since i found out what meat was! However, I have also been suffering from Irritable Bowel Syndrome and it makes it very hard for me to eat a healthy vegan diet, since fibrous foods (like fruit and veggies and beans and certain grains) aggrevate my symptoms (diahherria, constipations, extreme gas, cramps, pain). What can I do? I’ve had IBS for several years now and nothing has helped. I’ve been to countless doctors and specialist and even a homeopath, and none of these have helped. I’m 16 years old and its really taking a toll on my life. Do u have any suggestions? I’m taking extra-strength gas-x 4x’s a day, zoloft, and acidolphilous. I miss eating more variety and eating fruits and veggies and beans. Please help! thanks

A. Dear Shelby,

You’ve come smack up against one of the few real problems on a vegan diet: more fiber than your GI tract can handle. Fiber is mostly indigestible cellulose which is a long chain polymer of glucose. The fiber goes right through your small intestine and then dumps into the colon where there are bacteria that elaborate the enzyme cellulase. Cellulase splits glucose molecules off the ends of cellulose and the bacteria then metabolize the glucose, releasing gas and bowel irritants that lead to increased peristalsis, cramps, and diarrhea.

I don’t know if your doctors have worked you up for celiac syndrome but even if they have I would recommend a trial of a gluten-free diet for a week or two. Gluten is a protein in most grains, particularly wheat, that generates an auto-immune reaction in about 5% of the population. If it goes on long enough there’s microscopic damage to the intestinal lining, weight loss, and most of the symptoms you describe. I believe the vegan diet unmasks celiac syndrome in more people than the medical profession realizes and since there’s nothing in grain that you can’t get along without, it seems sensible to cut out all grains except perhaps boiled white rice for a couple of weeks and see what happens. If you’re a celiac most of your symptoms may be gone shortly.

Beans are tasty and fairly nutritious but they contain two indigestible five carbon sugars, raffinose and stachyose that can also cause big time gas. In spite of their reputation as the protein source for veg*ns beans actually contain less protein per Calorie than leafy greens, the foods that should make up a large part of any healthy diet.

If you’re eating the customary three squares a day it’s possible that the meals are so large that they are simply overwhelming your digestive resources. A properly designed vegan diet based on vegetables and fruit rather than starches and grains and meeting Calorie needs is about 1/3 larger by weight and volume than an equicaloric omnivorous meal. Frequent small meals rather than three large ones work well for many people and more closely mimic the feeding patterns of our primate ancestors who were herbivorous arboreal grazers rather than carnivorous gorgers.

For someone with your symptoms it’s very important to chew your food thoroughly so that it will be broken up mechanically and mixed with salivary amylase prior to swallowing. If you can’t do that, a Vita Mix blender can turn out a very smooth, nutritious, and tasty mix of vegetables, seeds, and herbs meeting the RDA for all nutrients save B12. That problem can be fixed by adding a teaspoon of Red Star nutritional yeast. There’s also an acidophilus product Töpfer Lactopriv/B Lactobacillus bifidus powder (vegan acidophilus substitute) available at health food stores. I haven’t been much impressed with adding it to the blender as a digestive aid but it’s worth a try.

I hope this will be of some help. If not, write again. I had similar symptoms for my first 25 years as a vegan which ended abruptly when I stopped eating bread and other glutinous grain products. That was after a gastroenterologist did a complete workup with tubes and gadgets in all available orifices and came up with the same diagnosis as yours, IBS.


-William Harris, M.D.


  • terri

    Fairly good article…except we as humans with a Creator don’t have primate ancestors, nor was our digestive system that takesI 3-4 hours to compleatly digest and empty the stomach of one meal meant to graze like a cow that has more than one stomach and a much shorter intestinal track. I do think the point about smaller portions is valid…especially if we are adding whole plant basebased raw at the rate of at least 50%, which is extremely important on many levels, not to mention all but forgotten about over the past 100 years. This will expand the stomach to the full state with a fraction of the amount of food that we have been used to. I can see that overloading the stomach and digestion would cause more IBS.

    Thank you for your efforts to educate. We must never stop learning…especially when it comes to matters of health!


    • Marvin

      I agree with your thoughts on this. It’s interesting how there is such a wide gulf between the ‘carnivore’ vs ‘veggie’ perspectives on nutrition. Those who espouse a vegan/vegetarian diet present things as you have. Those who promote a diet based on eating animals make totally different claims. Fortunately, honest science is on the side of a plant-based diet. 🙂 Be healthy and love it!

  • Superior thinking demosnrtated above. Thanks!

  • Jasmine Flower

    I am a huge fan of fiber. As an IBS sufferer and a health conscious person, I know fiber does all kinds of good things for me, including keeping me regular which sounds silly but isn’t so funny when a week passes and you feel like you’re about to explode. I was recommend the Lady Soma Fiber Cleanse by my doctor – and this is a fiber like no other. It is amazing. Each dose contains natural, soluble dietary fiber extracted from the seeds of the cluster bean.

    It is 100% natural fiber.I had never heard of Lady Soma products, but i am so glad they were recommended. So I am recommending them to you. . .its an excellent choice for maintaining regularity and supplementing you

    • Marvin

      @Jasmine Flower
      I’m curious if you know of any additional resources specifically relating to IBS and vegans. Thanks for the info on Lady Soma Fiber Cleanse!

  • Natasha

    I suffer with severe ibs and follow a vegan diet which hardly helps.This has beeb yrs. and I;m housebound.Please help.