Can You Get Enough Fiber on a Low-FODMAP Diet?

Following a low-FODMAP diet can relieve IBS symptoms. But it also eliminates a lot of healthy foods from your diet. Tamara Duker Frueman, author of The Bloated Belly Whisperer, joins me to talk about balancing good nutrition with symptom relief.

Monica Reinagel, MS, LD/N, CNS
6-minute read
Episode #589
The Quick And Dirty
  • Foods high in fiber can cause painful symptoms for those with IBS.
  • A low-FODMAP diet can relieve IBS symptoms but also eliminates a lot of healthy foods.
  • Most people with IBS can tolerate at least some categories of FODMAPS. 
  • Customizing your diet can help you maximize symptom relief without sacrificing nutrition.

The low-FODMAP diet can be very effective in reducing painful symptoms associated with irritable bowel syndrome (a disorder that affects up to 15% of adults). But the approach also eliminates a lot of healthy foods, including many vegetables and whole grains. How do we reconcile the low-FODMAP approach other dietary advice?

First, a little background for those who may not be familiar with FODMAPs.

What are FODMAPs?

The idea behind the low-FODMAP diet is that most IBS symptoms, such as bloating and abdominal pain, are triggered by certain types of carbohydrates that are poorly digested or absorbed. By avoiding foods that contain these specific carbohydrate molecules, the symptoms of IBS can be greatly reduced.

Since its introduction in 2005, numerous studies and clinical trials have shown the low-FODMAP diet to be extremely and uniquely effective—much to the relief of millions of IBS sufferers everywhere. 

The term FODMAP is actually an acronym for the types of carbohydrate molecules that are targeted in this approach: Fructans, Oligosaccharides, Disaccharides, Monosaccharides, and Polyols.

Do people suffering from IBS have to choose between symptom relief and the benefits of a higher fiber diet?

Foods that are high in one or more of these special molecules include wheat, rye, onions, legumes, lentils, dairy products, mushrooms, and cauliflower. The low-FODMAP diet also limits certain fruits, such as apples and pears, and sweeteners, such as honey, which are higher in fructose.

And here’s where it gets a little tricky. We talk a lot about the value of fiber in a healthy diet. Incorporating more fiber into your diet can help regulate blood sugar and cholesterol, manage your appetite and weight, and promote a healthy microbiome. But, many foods that are high in fiber are also high in FODMAPs.

Do people suffering from IBS have to choose between symptom relief and the benefits of a higher fiber diet? 

How to Balance FODMAPs and Fiber

Joining me to sort through this is Tamara Duker Frueman, registered dietitian and digestive specialist and author of The Bloated Belly Whisperer.

Monica Reinagel:

Tamara, in addition to your extensive knowledge of all things gut related, you also have very extensive clinical experience working with patients. And I want to share with you a couple of specific questions that I've gotten from my listeners.

Julie writes:

I have IBS and I generally follow a low-FODMAP diet, but all I ever hear is how bad white bread and white rice are. These are now diet staples for me. If I eat whole grains, it makes me feel bloated and miserable. So how do I balance this? Are refined grains like white rice really that bad for you.

And Theo writes:

A couple of years ago, I was diagnosed with IBS as well as Type 2 diabetes. I'm now managing my diabetes with diet and exercise, but trying to avoid FODMAPs makes that a real challenge.

We've talked before on the podcast about how beneficial fiber is. Do people with IBS have to sacrifice those benefits of a higher fiber diet?

Tamara Duker Frueman:

There's no generalizing for all people with IBS. We really have to look at an individual's tolerance and, you know, make the diet work for them. You have to customize the type of fiber to the person. When we just think in terms of high versus low, you lose a lot of nuance. A lot of people who feel really lousy after whole wheat are reacting to the insoluble fiber. But other whole grains have different types of fiber.

We really have to look at an individual's tolerance and make the diet work for them.

For example, whole grain oats have soluble fiber. And many of my patients with IBS find that easier to tolerate, especially if we do something to kind of modify its textural properties. So for example, steel-cut, oats are whole grain oats, but so are Cheerios, where the whole grains have been ground into a very fine flour. There's a good chance that you may tolerate that type of whole grain, but not whole wheat.


With enough experimentation and customization, can people following a low-FODMAP diet get enough fiber to support a healthy microbiome?


Most people can. Again, it's just a question of choosing which types of fiber. You don’t have to eat whole wheat. If it doesn't agree with you. There are other ways to get fiber. And maybe no whole grains work for you, but you do OK with squashes or fruits that don't have skins.and seeds, chia seeds, or whatever. Grains aren't the only food that has fiber.


The low-FODMAP diet has gotten so popular that a lot of people are doing it on their own without the benefit of guidance from a nutrition professional or a digestive specialist.  And I wonder whether they may end up restricting more foods than they actually need to.

In the first phase of the low-FODMAP diet, you try to clear all the FODMAPs out of the diet just to get that initial relief. But then there’s a second reintroduction phase where you systematically reintroduce different categories of foods. Some people may be sensitive to one but not others. But people who are doing this on their own may never do that reintroduction phase.


Yeah, that's exactly right. What often happens is a doctor will hand somebody a handout and suggest they try the low-FODMAP diet. And they never mention that this is supposed to be a diagnostic diet and that there is supposed to be a reintroduction period.

This is supposed to be a diagnostic diet and there is supposed to be a reintroduction period.

It only takes about two weeks on the diet for most people to know if it's going to help or not. And if it didn't help after two weeks, it's probably not going to help. And if it did help, most people can start reintroducing foods at that point.


How many people really are sensitive to all the FODMAPs across the board?


Most of my patients can tolerate at least one of the groups, if not more. If somebody is not able to handle any FODMAP foods whatsoever, I will often recommend them to get tested for SIBO (small intestine bacterial overgrowth), a condition that is often misdiagnosed as IBS


So many of the foods on the low-FODMAP diet are otherwise really healthy foods. We don't want people to restrict their diets more than they need to in order to feel well. We want to be able to incorporate as many of these healthy whole foods as are tolerable.


Absolutely. For the bean and brussel sprout family, which is notoriously hard for people. there is an enzyme called alpha galactose. A lot of my patients are able to tolerate those foods with an enzyme supplement. So utilizing all the tools we have at our disposal to maximize FODMAP tolerance is going to give somebody with IBS their best chance at as minimally restricted a diet as possible.


We're not talking about a wholesale endorsement of dietary enzymes as a category. There are many products out there that are pitched as all-purpose digestive enzymes that are not really supported by the science. You're talking about a very specific enzyme for a specific FODMAP. 


Yes, a lot of these random digestive enzyme cocktails won't even contain this particular enzyme. The important thing about enzymes is that they are specific. So if you don't use the right enzyme for the right food, it's useless.

The important thing about enzymes is that they are specific. So if you don't use the right enzyme for the right food, it's useless.


I just want to tackle one last question that Julie brought up. If people really can't tolerate whole grains, is it okay to eat some refined grains?


I think it really does people a disservice when we talk about individual foods as being healthy or unhealthy or good or bad. Individual foods really can't be assessed in terms of their healthfulness without the context of the entire diet. You can’t just say that it’s OK or not OK to eat white rice. What else are you eating?


That's right. And because of the relentless drumbeat of messaging about the value of whole grains, we sometimes lose track of how big a role the portion size plays. When we're talking about bread or pasta or rice, how much we're eating matters at least as much as whether it is whole grain or not.



Tamara has been a frequent guest on the Nutrition Diva. I hope you’ll also check out our previous conversations on bloating and intestinal permeability (aka leaky gut). I can also highly recommend her book The Bloated Belly Whisperer

About the Author

Monica Reinagel, MS, LD/N, CNS

Monica Reinagel is a board-certified licensed nutritionist, author, and the creator of one of iTunes' most highly ranked health and fitness podcasts. Her advice is regularly featured on the TODAY show, Dr. Oz, NPR, and in the nation's leading newspapers, magazines, and websites. Do you have a nutrition question? Call the Nutrition Diva listener line at 443-961-6206. Your question could be featured on the show.