Digestive Health Irritable Bowel Syndrome Nutrition Why Bran Is Bad for IBS By Barbara Bolen, PhD twitter Barbara Bolen, PhD, is a licensed clinical psychologist and health coach. She has written multiple books focused on living with irritable bowel syndrome. Learn about our editorial process Barbara Bolen, PhD Medically reviewed by Medically reviewed by Keri Peterson, MD on November 02, 2020 facebook twitter linkedin Keri Peterson, MD, is board-certified in internal medicine and operates a private practice, Age Well, in New York City. Learn about our Medical Review Board Keri Peterson, MD Updated on January 15, 2021 Print Table of Contents View All Table of Contents What Is Bran? IBS and Bran Causes and Explanations Bran Fiber Alternatives Eating foods that contain bran can make irritable bowel syndrome (IBS) symptoms worse. If you have the condition, it's a good idea to make sure you get enough IBS-friendly sources of fiber in your diet. But, when you have IBS, bran fiber can lead to stomach upset and constipation. Westend61 / Getty Images What Is Bran? Bran is a form of fiber derived from the hard outer layer of cereal grains like barley, corn, oats, rice, and wheat. Although bran can be derived from different cereal grains, products such as bran cereal and muffins are typically prepared with wheat bran. In addition to being a source of potassium, iron, magnesium, and vitamin B6, a one-cup serving of wheat bran can provide 100% of your daily recommended intake of fiber. Bran can be found in "all-bran" products and in products made with whole wheat flour. Whole wheat flour is comprised of the wheat germ (the inner part of the grain kernel), endosperm (the bulk of the grain kernel), and bran—all of which are milled together. The bran content aids in digestion and provides more nutritional components than refined flour. The Problem of Eating Wheat If You Have IBS IBS and Bran Research shows that bran tends to make IBS symptoms worse. In its 2014 review, the American College of Gastroenterology concluded that insoluble fiber sources, like wheat bran, are not recommended for IBS due to the risk of increased gas and bloating. Causes and Explanations There is no definitive answer as to why bran can be problematic for people with IBS, although researchers have begun to offer hypotheses as to why this form of fiber can worsen symptoms. One theory is that the hard bran shell is irritating to nerves in the lining of the intestines. As a condition characterized by the dysfunction of the brain-gut axis, IBS may be exacerbated by the physical strain placed on the enteric nervous system of the gut. Another possibility is that wheat bran contains fructan, a fermentable carbohydrate that's one of several substances classified as a FODMAP. Eating a diet high in FODMAPs is believed to be linked to an increase in IBS symptoms. Pros and Cons of the Low-FODMAP Diet An even simpler explanation is that a standard serving of wheat bran is simply too much for someone with IBS. As an insoluble fiber, wheat bran attracts water into the intestines, making stools softer and helping ease digestion. However, if you eat too much, it can increase gas production, leading to bloating and flatulence. Given that one cup of wheat bran represents a full day's allowance of fiber, it is possible that a person with IBS may simply be eating more bran than they should. This may explain why some people with IBS are affected by bran and others aren't. Cutting back on your intake of bran may be all that is needed to avoid your IBS symptoms. Over time, you could consider increasing the amount of bran you eat as your body becomes more tolerant of this fiber. Can a Ketogenic Diet Reduce IBS Symptoms? IBS-Friendly Fiber Alternatives If wheat bran is causing you problems, there are other fiber alternatives you can consider. Good sources of insoluble fiber include: Apples (unpeeled)BeansBlackberriesCauliflowerCollard greensGreen beansGreen peasKaleNutsPotatoesPrunesSpinach You may be able to tolerate non-wheat sources of bran, particularly if constipation is an issue. In terms of fiber supplements, psyllium (also known as an isphagula husk) may help alleviate IBS symptoms. Another option is ground flaxseed, which can help if constipation is the predominant symptom of your IBS. Although a diet high in fiber is optimal for digestive health, some studies suggest that it may be more beneficial for people with constipation-predominant IBS (IBS-C) than the other IBS subtypes. A Word From Verywell There is mounting evidence that the soluble fiber in fruits, vegetables, and legumes may be better tolerated in people with IBS than insoluble fiber. If you're unsure of which sources of fiber are best for you, consider meeting with a dietitian experienced with IBS to work out a dietary plan. Oftentimes, finding the best fit takes trial and error. Irrespective of the type of fiber you consume, it is best to use a gradual approach when increasing your fiber intake to allow your body to adjust to the change. How to Find a Dietitian to Help Your IBS Was this page helpful? Thanks for your feedback! One of the most challenging aspects of having IBS is trying to figure out what's safe to eat. Our recipe guide makes it easier. Sign up and get yours now! Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit Article Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. U.S. Department of Agriculture. Wheat bran, crude. In: FoodData Central. Updated April 1, 2019. Francis CY, Whorwell PJ. Bran and irritable bowel syndrome: time for reappraisal. Lancet. 1994;344(8914):39-40. doi:10.1016/s0140-6736(94)91055-3 Ford AC, Moayyedi P, Lacy BE, et al. American College of Gastroenterology monograph on the management of irritable bowel syndrome and chronic idiopathic constipation. Am J Gastroenterol. 2014;109 Suppl 1:S2-26. doi:10.1038/ajg.2014.18 Mayer EA, Savidge T, Shulman RJ. Brain-gut microbiome interactions and functional bowel disorders. Gastroenterology. 2014;146(6):1500-12. doi:10.1053/j.gastro.2014.02.037 Marsh A, Eslick EM, Eslick GD. Does a diet low in FODMAPs reduce symptoms associated with functional gastrointestinal disorders? A comprehensive systematic review and meta-analysis. Eur J Nutr. 2016;55(3):897-906. doi:10.1007/s00394-015-0922-1 El-Salhy M, Ystad SO, Mazzawi T, Gundersen D. Dietary fiber in irritable bowel syndrome (Review). Int J Mol Med. 2017;40(3):607-13. doi:10.3892/ijmm.2017.3072 Cockerell KM, Watkins AS, Reeves LB, Goddard L, Lomer MC. Effects of linseeds on the symptoms of irritable bowel syndrome: a pilot randomised controlled trial. J Hum Nutr Diet. 2012;25(5):435-43. doi:10.1111/j.1365-277X.2012.01263.x Cozma-Petruţ A, Loghin F, Miere D, Dumitraşcu DL. Diet in irritable bowel syndrome: What to recommend, not what to forbid to patients. World J Gastroenterol. 2017;23(21):3771. doi:10.3748/wjg.v23.i21.3771 Additional Reading Ford AC, Moayyedi P, Lacy BE, et al. American College of Gastroenterology monograph on the management of irritable bowel syndrome and chronic idiopathic constipation. Am J Gastroenterol. 2014;109(S1):S2-26. doi:10.1038/ajg.2014.187