Understanding the Subtypes of IBS

Written by: Jessica Roocroft, RD

Updated: November 20th, 2024

Let’s dive into the wild world of Irritable Bowel Syndrome (IBS) and the Subtypes of IBS. IBS is now categorized as a DGBI: A Disorder of the Gut-brain Interaction. Essentially this means our gut and brain have started to misinterpret signals from the normal processes of digestion into physical sensations of pain. Changes in how fast and slow our gut moves (called “motility”) can also become altered. Our gut microbiota (the community of tiny living organisms like bacteria, viruses, and fungi that live in your digestive system, mostly in your intestine) can also become impacted…usually not for the better.

Did you know that understanding the different “flavours” of IBS (which are based on the Rome IV criteria) can be a game changer in managing this frustrating condition?

It’s true. Each subtype comes with its own unique set of symptoms and challenges that needs a tailored approach.

In my practice, a multi-modal approach (meaning we don’t just do one thing, rather we approach it from various angles from diet to lifestyle changes) seems to produce the best results for all subtypes of IBS.

So buckle up and let’s break down the four main subtypes of IBS, and what seems to work best for each based on the science and the clinical experience of a Registered Dietitian with a practice dedicated exclusively to serving those with IBS.

IBS with Diarrhea (IBS-D)

First up, we have IBS with Diarrhea, or IBS-D.

IBS-D can feel like most meals come with a side of urgency. We’re talking frequent, loose, or even watery stools (that are non-bloody) that might leave one feeling like searching out the nearest bathroom is their full time job.

Keys to managing IBS-D:

(Temporary) Low FODMAP Diet Elimination Phase.
- FODMAPs are a group of poorly digested, fermentable carbohydrates found in foods like: garlic, onion, leek bulb, shallot, beans/legumes, lactose (in “wet” dairy foods like milk), mushrooms, cauliflower, celery, apples, pears, honey, mango, and dried fruit. By reducing these in the diet (also known as the “Gentle” Low FODMAP Diet) less water is dragged into the bowel, and less gas is produced when FODMAPs meet our estimated 5 pounds of gut microbes in the large intestine. This can mean less pain, bloating and diarrhea for those with IBS-D.
Soluble Fibre Therapy:
- Thanks to its property of viscosity, the right soluble fibre therapy helps ‘gel’ stools, and reduce diarrhea and loose bowel movements. The most tolerated by my patients seem to be partially hydrolyzed guar gum (PHGG) and acacia senegal.
Lowering foods that tend to increase gut speed, like coffee, large salads (AKA “roughage”) and large smoothies.
Gut directed hypnotherapy, or cognitive behavioural therapy:
- As IBS is now categorized as a disorder of the gut-brain interaction, giving our gut-brain axis some much needed attention seems to be a highly effective, non-restrictive approach to managing IBS.
  - This may be is especially important when someone should not restrict their diet (for example, those with an already restricted diet, or those with, or at risk for, eating disorders or disordered eating).
There are also meds to help slow things down or reduce certain “gut bugs” implicated in IBS-D, such as the antibiotic Rifaximin, and so on- so don’t hesitate to ask your healthcare provider.

IBS with Constipation (IBS-C)

On the flip side, we’ve got IBS with Constipation (IBS-C). If you’re more familiar with the struggle of infrequent, hard, or lumpy stools, this one’s for you.

Keys to managing IBS-C:

(Temporary) Low FODMAP Diet Elimination Phase. Per above, but noting that FODMAPs can slow down the gut of those with IBS-C rather than speed it up like in IBS-D. This is likely thanks to the differences in the types of microbes that can be found in the guts between IBS subtypes.
Hydration & movement.
Gut directed hypnotherapy, or cognitive behavioural therapy. See above.
Increasing foods that can help to increase gut speed, like coffee, large salads (AKA “roughage”) and large smoothies- yes that’s right: this is the opposite advice compared to IBS-D! This highlights the importance of getting information specific to one’s IBS subtype.
Taking a nightly “water magnet”.
- Those with IBS-C might be served well to talk to their doctor and see if taking a dose of Magnesium citrate at night would be safe to try.
- At certain doses magnesium salts, like magnesium citrate, can pull water into the bowel overnight as we sleep, and can result in a more regular morning bowel movement routine, with softer stools, making “rabbit pellet” poops a thing of the past.
  - Those with kidney disease, and other specific conditions may not be suitable for this tip. If that is the case, PEG (RestoraLAX) is another “water magnet” to consider.
There are also meds to help get things moving, reduce certain “gut bugs” implicated in IBS-C, and so on- so again don’t hesitate to seek help.

IBS with Mixed Symptoms (IBS-M)

Next, we enter the realm of IBS with Mixed Symptoms, or IBS-M. This one’s the overachiever of the group, giving you the best (or worst) of both worlds: alternating diarrhea and constipation. Did you know, however, that IBS-M is thought to be rooted in constipation as opposed to diarrhea? This is why a combination of the strategies for IBS-D and IBS-C may work well.

Keys to Managing IBS-M:

A mixture of the above strategies. Chat with your IBS trained Registered Dietitian, and your Healthcare provider, to create a plan that works best for you.

IBS Unclassified (IBS-U)

Finally, we have the enigmatic IBS Unclassified (IBS-U). This is where you land if your symptoms don’t fit neatly into the other three categories. Diagnosis and treatment for IBS-U can be a bit of a rollercoaster, but don’t lose hope. A tailored approach is usually the way to go, much like folks with IBS-M.

Conclusion

So, there you have it – the not-so-glamorous but oh-so-important breakdown of IBS subtypes. Knowing which type you’re dealing with can up your chances in managing symptoms well.

If you suspect you’re part of the IBS club, don’t go it alone. Consult a healthcare professional who can help you pinpoint your subtype and craft a management plan that’s as unique as you are.

About Writer Jessica Roocroft, RD

I’m a Registered Dietitian from North Vancouver, BC who owns and operates an Irritable Bowel Syndrome focused private practice.

Most importantly, I know first-hand what it’s like to deal with gut drama due to IBS.

My mission is three-fold:

1. Encourage and advocate for Canadians to get properly diagnosed with IBS (including their subtype).

2. Give people a step-by-step process for their type of IBS (and any other layers to their story, such as SIBO or Histamine Intolerance), with as few restrictions as possible.

3. Supporting patients along the way to get them feeling comfortable in their body again (finally)!

It’s my life’s work to combine my lived experience with IBS with my hundreds of hours of research and continuing education over the years and direct it right back at supporting clients navigate the overwhelming world of IBS.

I love sharing my IBS-related knowledge with family doctors, nurse practitioners, fellow RDs and the public-

…because if 1 in 7 human beings on this planet have IBS, we all need to pull together to facilitate the best care possible (millions of people feeling better?? Sign me up for that version of Earth always)!

A little more about me:

I am based in the mountains of North Vancouver, British Columbia, Canada, where I run my private practice Jess Nourishes, and my signature online IBS Programs called IBLess. There is one for each subtype of IBS (Diarrhea, Mixed and Constipation).

Check out my library of free IBS Mini Guides on my website- there’s one for each subtype waiting for you to download!

Professional Bio

Jessica Roocroft is a Registered Dietitian based in North Vancouver, British Columbia, Canada. She earned both her science degrees (Biology, 2008, and Food, Nutrition & Health, Dietetics Major, with Honours) from The University of British Columbia. She is also trained by Monash University in the use of the Low FODMAP Diet for IBS, and has taken the Clinicians Course in Gut Directed Hypnotherapy by Mindset Health.

After Jessica completed her Dietetic internship at the Vancouver Island Health Authority she was awarded a role in the remote North of Vancouver Island, in charge of three hospitals, managing all inpatient clinical and food service operations.

After taking on other roles in management and leadership, Jessica moved into the private practice space.

In 2019 she founded Jess Nourishes, which quickly became known in BC for helping clients with IBS; something Jessica has lived experience with.

In 2021 she launched her first online IBS program My Bloat Code, and in 2022 she completed FODMAP Training with Monash University.

That same year, she created her signature program for busy, food loving people with diarrhea-predominant IBS (IBS-D).

Then in 2024, she founded IBLess, a group of 1:1/group virtual hybrid IBS programs- with one program dedicated for each IBS Subtype: Diarrhea, Mixed, and Constipation.

She matches her client’s IBS subtype, dietary and lifestyle preferences with her science-based curated IBS tools and strategies in order to manage IBS symptoms as effectively and sustainably as possible.

Jessica truly believes that a combination of lived experience with IBS, plus ongoing research, curiosity and training allow her to bring about the most heart-based, empathetic care for her fellow “IBS Comrades” through her small (but mighty) practice.

Publications

Description of Practice

Jessica’s mission is to translate tricky IBS science into plain English, give clients a step-by-step process as to how to soothe symptoms with her library of effective, science-based, client-tested IBS tools, and get busy food-loving people with IBS feeling comfortable in their bodies (finally). She does this through one-on-one counseling, posting free IBS self help resources, and through her online programs.

She practices in the following conditions/issues:

Diarrhea
Irritable Bowel Syndrome (IBS), in particular IBS-D
Food intolerances & sensitivities
Small intestinal bacterial overgrowth (SIBO)
Bloating
Constipation
Abdominal pain / discomfort

Click here to connect with Jessica to learn more about her services, innovative IBS programs, speaking, and writing, or email her at jessica@jessnourishes.com

You can also follow her on Instagram @jess_nourishes