FODMAP Dietitian Expert Interview with Patsy Catsos

Patsy Catsos (MS, RD, LD) is a nutritionist/dietitian and one of the world’s leading IBS & FODMAPs specialists. She is also Past-President of the Maine Dietetic Association, author of IBS–Free at Last!, writer of, and maintains a private practice in Portland, Maine.

LowFodmap Q1 – Thanks for agreeing to this interview. How did you become involved in the world of FODMAPs and what is your area of expertise?

Patsy Catsos:

These are the questions you should always start with! I advise consumers to “consider the source” when evaluating internet information about IBS and FODMAPs, so it is only fair to offer a bit more about my point of view before answering the questions you have collected. First of all, I share your history of miserable GI symptoms (ulcerative colitis since 1985, IBS). When patients talk to me about the gory details of their problems, they are talking to someone who does not have to be convinced of what is at stake.

Professionally, [highlight]I am a registered dietitian with a bachelor’s and master’s degree in nutrition[/highlight], job experience as a research dietitian and nutrient database manager at Tufts New England Medical Center, and currently working as a dietitian/nutritionist in private practice.

I am essentially an expert at translating medical research and food composition data into usable tools for my patients and readers. I spend much of my time reading research papers related to IBS and FODMAPS and figuring out the most effective ways to interpret and communicate that information to my readers. I rely on internationally published scientific original sources for my data (much of it produced by researchers in Australia), but use my own ideas to create tools such as menus, label reading tips, recipes, shopping lists, and so on. I use my critical thinking skills and a lifetime of experience with food composition data to make educated guesses when accurate information is not available.

I am located in the United States. As an active member of my professional association and as a writer, I have worked hard to get the word out to dietitians and physicians about the power of FODMAPs-restricted diets to help many IBS patients. Although I felt like a voice in the wilderness just a few years ago, the FODMAPs concept is becoming more mainstream.  A couple things I am not: I am not a member of an academic body that sets standards of care for IBS patients, nor am I personally engaged in producing nutrient data about the FODMAPs composition of foods.

IBS diagnosis in the United States has improved by leaps and bounds, but other than Maine and a few other rare places, where can the majority of IBS sufferers get professional help with IBS? Patients country-wide are still often being told that “it’s in their heads” or are offered anti-depressant drugs.

LowFodmap Q2 – Is there a network of IBS/FODMAPs specialists that patients ought to know about?

Patsy Catsos:

A dietitian (Registered Dietitian in the U.S., Accredited Practicing Dietitian in Australia, etc.) is by far your best bet for getting credible, effective help with food-related functional gut disorders. It is outside the scope of our practice to diagnose IBS, but when it comes to day-to-day management of any kind of medical diet, the right dietitian can help you immensely. As a service to both readers and colleagues, I have recently posted a link on my web site,, to a directory of FODMAPs-knowledgeable registered dietitians who are accepting new clients. I hope this directory will grow and grow!

If you don’t see anyone in your area in my directory, go to, click on “find a nutrition professional” and select the check box for “digestive disorders”. Or, ask your gastroenterologist for a referral to a registered dietitian in your area with a special interest in digestive disorders. Call the dietitian and ask whether s/he is familiar with FODMAPs. The basic concepts behind the FODMAPs diet are familiar to dietitians, however the specific food lists and strategy for the elimination diet may be new for many. Your dietitian will be more equipped to help you given the opportunity to gather resources before your visit. Professional materials about FODMAPs can be ordered from my web site. If you would like me to coach you, I am available via phone or skype. See the link in the sidebar of

LowFodmap Q3 – Do you travel and do presentations for awareness? 

Patsy Catsos:

I do not have a lecture circuit, but I do speak at professional events. I am experimenting with webinars for dietitians, and would consider doing a webinar for IBS patients if there seems to be interest in the idea. Actually, it would not be correct to call webinar attendees “patients” since I would not be collecting any personal health information or conducting any assessments on the attendees. The event would be purely educational in nature. If anyone would like to collect a few names for a pilot webinar, I would be game.

LowFodmap Q4 – Since IBS as a conventional diagnosis is simply left at THAT and finding the causes and utilizing a specific diet are fairly new, have you received any backlash from (what I would call) the conventional medical field for your book and research? What about support?

Patsy Catsos:

There has been a very little backlash from conventional medical practitioners for the material in my book (I don’t do original research in my practice setting). I think that is because anyone trained in the medical field can quickly recognize the inherent logic of the FODMAPs concept if they take even a few minutes to read through professional materials on the subject. One influential doctor in the field of functional gut disorders, William Chey, MD, University of Michigan, was heard to say publicly several years ago that FODMAPs was too complicated for patients to implement in a meaningful way. I sent him a letter and a copy of my book, and his most recent writings are very favorable toward the utility of the FODMAPs approach. Who can argue with success? Doctors who refer to me may not have heard of the FODMAPs approach at first, but they certainly hear it loud and clear when their patients tell them how much better they feel!

There are some potentially valid concerns about the diet that I share and address directly with readers of my book and blog: the diet is not right for everyone, many people need professional assistance from a trained dietitian to implement the diet, people should eat the widest and most liberal diet possible to get a wide range of nutrients, and so on. Please remember that information you read in a book or online is not a substitute for professional advice or individualized medical nutrition therapy. Q5 – We have the FODMAP diet, we have the Specific Carbohydrate Diet, your FODMAP-elimination diet, of course, MRT/LEAP diet and no doubt others. How on earth does one decide which one is right for them?

Good question. As you know, I do not believe in one-size-fits-all diets for IBS, so there is no one right answer to this question! Altered gut function can be related to a number of adverse food reactions–some involve the immune system and others do not. First one must try to identify which type of adverse food reaction is occurring, then choose the diet approach that will address it. You should work with your doctor and dietitian to figure this out.

Clues that FODMAPs are the issue include the following statements from the patient:

  • My symptoms are primarily gas, bloating, abdominal pain, flatulence, diarrhea, urgency or constipation.
  • I have tested negative for celiac disease, parasites, Crohn’s disease, ulcerative colitis, microscopic/lymphocytic colitis, diverticulitis, cancer
  • I do have Crohn’s or colitis in remission, but I still have symptoms
  • I do not have a fever or bloody stools associated with my symptoms
  • I’ve had a positive fructose or lactose malabsorption test
  • I might be lactose intolerant, can’t quite figure it out
  • Bread makes me feel bloated
  • I love fruit and eat loads of it
  • I eat lots and lots of fibre but my IBS doesn’t get any better, in fact it might be worse
  • I felt better when I tried a low-carb/paleo/Atkins/SCD diet
  • It’s gotten worse as I get older
  • I drink lots of sweetened carbonated beverages, candy, ketchup, BBQ sauce, honey
  • My mouth is dry, so eat a lot of sugar-free candy and gum
  • I’m a vegetarian and get most of my protein from soy foods and other legumes
  • I’m an athlete with very high calorie needs
  • The healthier I eat, the sicker I get–I just stay away from fruit, veg, and milk products

This next idea is critical: the effects of FODMAPs are primarily limited to the gastrointestinal tract, and the effects are usually over within hours or days after the offending sugars and fibers have been expelled from your body and you have recovered from the pain.

In my practice, if the patient has multiple health issues consistent with food-chemical or food sensitivities, such as migraine headaches, classic food allergies, aching body, hives, malaise, chronic sinus problems, other autoimmune or inflammatory conditions, etc, then I use mediator release testing to build a highly customized elimination diet based on the results of their blood test. (Food chemicals may be additives or naturally occurring. Examples are MSG, solanine, amines, salycilates, food dyes, nitrates, or caffeine.)

As for the other diets, I don’t doubt they may relieve symptoms for some people. I keep an open mind and will always be interested in new evidence for any approach that will help my patients. I am not intimately familiar with the details of other IBS diets, but I will offer some brief comments.

  • Specific Carbohydrate Diet (SCD): Elaine Gottschall was on the right track, but in my opinion this diet is outdated and too restrictive for patients with IBS if followed in its original form. I don’t agree with the degree of rigidity required by the diet–it just isn’t necessary for most people with IBS to never, ever have specific carbohydrates in any amount whatsoever. I take a much more experimental approach. We know now that a greater range of lactose-free milk products work well for many people with IBS, and that high fructose foods such a honey and apples, which were allowed on the SCD are problems for many IBS sufferers.
  • Heather Van Vorous/ Heather has clearly helped many IBS sufferers by bringing attention to the whole issue of IBS and diet. Her approach may have been up-to-the minute in 2000, but now we know that “low-fat” and “no red meat” diets across the board for IBS are not necessary. A large part of her business is devoted to promoting fiber supplements for IBS, but the most recent studies have shown that fiber supplements help a minority of people, but fact, eight recent reviews have uniformly concluded that fiber has little or no benefit for most IBS patients. Results of a clinical trial published in the British Journal of Medicine in 2009 found that in order to yield one patient with adequate relief of abdominal pain or discomfort during the first  month of treatment, between four (psyllium) and thirty-three (bran) patients must be treated with fiber supplements! Though acacia fiber was not included in this trial, it is safe to say that fiber therapy in general does not have good odds of effectiveness v. theFODMAPS-restricted approach, which can help up to 75% patients with IBS get adequate relief.
  • Paleolithic Diet: Interesting concept! In doing a paleolithic diet, most FODMAPs are automatically eliminated, so it probably works pretty well to manage IBS for a lot of people. I especially appreciate that limited access to sweeteners throughout most of human history should probably guide current practice. But I think that humans are essentially opportunistic feeders and are meant to eat any food they can tolerate, so it doesn’t make sense to me that no one should eat potatoes or milk or any other category of food without consideration of individual tolerance.

LowFodmap Q6 – Are new formal classifications of IBS (beyond IBS-C and IBS-D — perhaps IBS-C/LI or IBS-D/FM) being discussed in professional circles in order to better help treat IBS with diet?

I’m not sure. I do know there is growing appreciation in professional circles of the role food plays in generation of IBS symptoms.  I will have to leave it to physicians to debate the finer points of medical diagnosis. As a dietitian, I take a more functional approach. No matter what the medical diagnosis, we can improve symptoms and overall wellness by manipulating the diet.

Here is one hair I do think is worth splitting: the difference between a FODMAPS elimination diet and a FODMAPS-restricted diet. An “elimination diet” is a strict, temporary, learning diet that we do to learn what foods or food categories trigger symptoms. A FODMAPs-restricted (or controlled) diet is what we do going forward after we learn what our problem areas are, with the ultimate goal of the most liberal, varied diet possible. Please be clear with yourself which one you are doing. This will help you answer a lot of questions for yourself about whether is OK to eat foods that contain borderline amounts of FODMAPs. While it is not recommended to eat raisins or green beans during a FODMAPs elimination diet, for example, going forward you may find you are perfectly well able to tolerate small, controlled portions of these foods.

Another distinction that deserves more attention is the distinction between FM (fructose malabsorption) and FODMAPs intolerance. It is true that original research in the area of FODMAPs and IBS linked the two because subjects were qualified for the studies by having IBS and being positive for fructose malabsorption. Clearly,  fructose is one of the FODMAPs that can cause symptoms for patients with IBS.

But it is a mistake to overgeneralize that anyone with dietary fructose intolerance automatically cannot tolerate other FODMAPs, especially fructans. The fact that fructans consist of links of fructose doesn’t mean much at all. Fructose is poorly tolerated due to the limited rate of fructose absorption in some people. Fructans never do get broken down to fructose because humans lack the enzyme for that; they are poorly tolerated due their own rapid fermentation and osmotic activity. While it is true that people with fructose malabsorption ALSO poorly tolerate fructans and other FODMAPs, they are not the same thing. Polyol (sorbito, mannitol) intolerance is actually more closely linked to fructose intolerance than fructans, because consuming it has the effect of worsening fructose absorption. Discovering these finer points in your own body is the purpose of the challenge phase of a FODMAPs elimination diet.

LowFodmap Q7 – Lastly, it seems like many FMers see staying on top of the most recent food FODMAP data as a constant struggle – there is no centralized, updated, managed repository of FODMAP-centric Nutritional information and printed books are quickly deprecated. What do you see occurring to help solve this problem in the future – are you aware of any ongoing projects that aim to resolve this?

I would counsel your readers to keep their eyes on the big picture.

Most people with FODMAPs intolerance are not sick because green bell peppers/capsicum have .37 grams per 100 grams more sorbitol than red bell peppers/capsicum. They are sick because their bodies can’t handle large serving of milk, yogurt, ice cream, fruit, onions, garlic or beans and the modern diet contains too much bread, bagels, pasta, high fiber bars and cereals, artificial sweeteners, sugary beverages and juices. After experimenting with a FODMAPs elimination diet, they will usually find they can[highlight] manage small portions of most foods and limiting the total FODMAPs load of the meal/day.[/highlight]

I do not say this in any way to disrespect those people who find that .37 grams of sorbitol DOES make a difference; I know many of them and it is a very real problem. I am very sympathetic to those who are sensitive to even the most minute amounts of FODMAPs, because even when better composition tables are available, FODMAPs composition of foods will continue to be a moving target. It will continue to be affected by analytical methods, processing, cooking, ripeness, botanical variety, growing conditions, storage, preparation methods and more.

From Thank you for your time, Patsy 

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