IBS - Irritable Bowel Syndrome
By: Lynsey Martin
What is it?
IBS is a functional gastrointestinal disorder that affects approximately 10-15% of the population and is more common in females than males. It involves the gut-brain axis and is characterized by microbial dysbiosis, altered immune and inflammatory responses in the intestine, an increased awareness and sensitivity to gut distention, as well as possible CNS dysregulation. It is often linked to psychological disorders like anxiety and depression. The root cause is not always known but can sometimes stem from an infection (like bacterial dysentery) or can be sporadic/non-specific.
*It is not based on structural damage or biochemical abnormalities like Irritable Bowel Disease (IBD). Thus, eating symptom-causing foods for those with true IBS does not cause any actual damage.
What are the symptoms?
The main symptom of IBS is recurrent abdominal pain associated with a change in bowel habits.
To be diagnosed as IBS, at least 2 of the 4 symptoms must be present and must be ongoing for 6+ months:
- Altered stool passage – straining or urgency or incomplete evacuation
- Abdominal bloating
- Distension or hardness made worse by eating
- Passage of mucous
There are 4 Sub-Type of IBS
How is IBS treated?
IBS is diagnosed by first excluding other disorders like Celiac Disease or IBD. After exclusion, there are 2 “lines” of treatments:
First Line Treatments
- Making dietary changes that include decreasing alcohol, caffeine, spicy, and fatty food intake
- Fibre intake changes
o For subtype 1 (diarrhea-predominant) – decrease fibre intake (temporarily – pros and cons of doing so must be weighed)
o For subtype 2 (constipation-predominant) – increase foods with high proportions of soluble fibre (ex. Psyllium husk or flaxseed*)
- Possibly manipulate dairy intake – this is often a dose-dependent sensitivity and can be reintroduced slowly after eliminating for a period of time
- Stress management
- Increase low- to moderate-intensity exercise
*flaxseed has been shown to potentially be more effective than psyllium husk in constipation-predominant IBS
If there is no improvement in symptoms…
Second Line Intervention: Low FODMAP Diets
What are they?
FODMAP = Fermentable Oligosaccharides Disaccharides Monosaccharides And Polyols
- A group of compounds, NOT an individual constituent in the diet
- They each can affect the bowel in a different way:
o Oligosaccharides are not readily broken down in the human digestive tract because we don’t have the enzymes required but they can undergo fermentation in the gut, producing more gas (hydrogen or methane), and leading to bloating, pain, and flatulence
o Disaccharides (like lactose) and Monosaccharides (fructose in particular) exert an osmotic effect in the small intestine leading to distention and other IBS symptoms
o Polyols similarly exert an osmotic effect
Low FODMAP is not a diet for life, it is a clinical intervention with 3 phases:
- Remove all FODMAP foods, aiming to still get adequate nutrients from other foods like fibre through foods like flax, calcium from leafy greens, etc.
*If there is no symptom resolution, the diet is over
*If there is improvement, proceed to:
- A specific approach is used for each IBS subtype, oligosaccharides are usually prioritized due to their function and importance as prebiotics
- Personal threshold tolerance to specific FODMAP foods is assessed
- The goal is to return as many foods as possible
- Long Term Management
- The ultimate goal is to strike a balance between symptom management while minimizing restriction, with the individual finding and understanding their own thresholds for particular FODMAP-containing foods
*This is not a catch-all for everyone with IBS, some will experience partial alleviation of symptoms, some will find full relief, and others (~30%) will not respond to this approach. It’s not wise to embark casually on your own low FODMAP diet, it should be a protocol led by a professional.
It is also important to mention that the production of hydrogen from carbohydrate breakdown is normal, it occurs in healthy people as well as those with IBS. Sometimes the actual presence and amount of hydrogen is the same but only in those with IBS does it correlate with pain and bloating. Additionally, some degree of bloating depending on the type of food and the quantity of it is normal but people can sometimes pathologize it.
Soluble or insoluble fibre in irritable bowel syndrome in primary care? Randomized placebo control trial. DOI: https://doi.org/10.1136/bmj.b3154
A diet low in FODMAPs reduces symptoms of irritable bowel syndrome. DOI: https://doi.org/10.1053/j.gastro.2013.09.046
Low fermentable oligosaccharides, disaccharides, monosaccharides, and polypols diet and irritable bowel syndrome in Asia. DOI: https://dx.doi.org/10.1002%2Fjgh3.12125
Diet Low in FODMAPs Reduces Symptoms of Irritable Bowel Syndrome as Well as Traditional Dietary Advice: A Randomized Controlled Trial. DOI: https://doi.org/10.1053/j.gastro.2015.07.054