Digestive health can already be pretty confusing, but adding in all the “gut health” talk, and it starts to sound a little scammy.

While some information is confusing at best and harmful, pseudoscience at worst, there is evidence-based “gut health” support, which is better known in the Medical Nutrition Therapy field as digestive health.

Digestive health is an umbrella term over various areas of the digestive system and individual needs. Different digestive situations can look very different with protocols between people. This is just one reason why it’s frustrating to have companies, like Plexus, encourage their distributors to treat “gut health”, as you don’t need any licensing to sell and they take an overly simplistic view of gut health treatment.

By the time I’m typically working with someone’s digestive health case, they’ve usually been through multiple doctor visits that have either ruled out the following, or have identified the following by tests.

Tests for exclusion:

Celiac disease

  • There are a few different ways of diagnosing.
  • Gluten intake should be adequate before testing to prevent false negative results.
  • Protocols typically include a strictly gluten-free diet, and nutrition education to reduce micronutrient deficiencies from excluding gluten.

Inflammatory bowel disease (IBD) – Crohn’s disease, Ulcerative Colitis

  • There is no single test that confirms the diagnosis of IBD.
  • Diagnosis is typically made based on physical examination, patient history and various tests, including blood tests, stool examination, endoscopy, biopsies, and imaging studies.
  • Symptoms are typically managed through prescription drugs and diet/intake – which can change during a flare.

Diverticular disease (overlaps with IBD and Irritable Bowel Syndrome)

  • Diverticula can be seen on a barium enema or endoscopy (flexible sigmoidoscopy or colonoscopy).
  • Diverticulitis can be diagnosed based on clinical examination during an acute attack and is usually confirmed with a CT scan.

Bowel Cancers

  • Nutrition-related treatment is based in increasing nutrient status, supporting intake while experiencing mouth sores and other side effects of treatments, and supporting hunger drive (as low appetite is often experienced).

Pancreatic exocrine insufficiency

  • Diagnosed with some indirect tests.
  • Protocols typically involve targeted pancreatic enzyme replacement therapy.

Bile acid malabsorption

Others – we’ll talk more about those in a bit and how they are related

  • Pelvic floor disorders
  • Endometriosis
  • Endocrine disorders (hyperthyroidism)

Pseudo-diagnoses are diagnosis based on uncertain scientific principles and present a risk to patients as their label may delay correct diagnosis and treatment. This can include some food sensitivity tests, leaky gut, and more.

Irritable Bowel Syndrome (IBS) is a Functional Bowel Disorder (FBD).

FBDs are diagnosed using symptom criteria, and after the exclusion of other gastrointestinal diseases (listed above)

FBDs include:

  • functional diarrhea
  • functional constipation;
  • functional abdominal bloating/distention;
  • unspecified FBD; and
  • opioid-induced constipation

IBS is thought to affect between 7-15% of the population worldwide, and is more common in women than men and most often diagnosed before the age of 50 years. Although IBS is a relatively common condition, it often goes undiagnosed. Undiagnosed IBS is problematic for the patient and can negatively impact their quality of life.

Causes of IBS

The cause of IBS is unknown, but is likely to be multifactorial. Factors proposed to cause IBS include:

  • Altered gastrointestinal motility
  • Visceral hypersensitivity
  • Impaired perception and processing of information by the brain
  • Low grade inflammation
  • Immune system activation
  • Intestinal permeability
  • Alterations in the gut microbiota.
    • This can include Small Intestinal Bacterial Overgrowth (SIBO)
    • This specific reason is why so many MLM distributors get so hyper-focused on “gut health”, even though there is so much more than our microbiome when it comes to IBS and negative digestive symptoms in general.

Major IBS symptoms

  • lower abdominal pain
  • altered bowel habit (diarrhea, constipation, or a combination of both)
  • bloating (the feeling that there is an inflated balloon in the abdomen)
  • excessive passage of gas
  • distension (a visible increase in abdominal girth)

These symptoms often ebb and flow, and symptom severity varies within and between individuals.

Diagnosis of IBS

Symptoms play an important role in establishing a positive diagnosis as there is currently no tests to diagnose IBS. Typically IBS diagnosis is done by a physician who takes into account symptoms, history, and with use of the Rome IV criteria.

These criteria allow IBS to be classified by predominant symptom type:

  • IBS-C (constipation predominant)
  • IBS-D (diarrhea predominant)
  • IBS-M (mixed bowel habits)
  • IBS-U (unclassified)

We can use the Rome criteria (above) to refer to the Bristol Stool chart (below), a tool designed to classify bowel movements. If you’ve worked with me for digestive health, you’re probably familiar with this chart!

Basically though, the reason why we want to rule out the conditions mentioned in the beginning of this article, BEFORE implementing IBS nutrition protocols, is because symptoms of IBS (abdominal pain, bloating, altered bowel habit, excess gas, incomplete evacuation and nausea) overlap with many other diseases, so there is potential for misdiagnosis.

These overlapping symptoms mean it is important to look for ‘red flags’ that may indicate the presence of conditions other than IBS, and that may require further investigation and medical input outside of the scope of a registered dietitian.

Red Flags:

  • Unexplained weight loss
  • Family history of bowel diseases
  • Age of onset > 50 years
  • Persistent daily diarrhea
  • Nocturnal bowel movements
  • Rectal bleeding / anemia
  • Fever
  • Recurrent vomiting
  • Progressive/severe symptoms


Breath testing

  • Breath tests have be used to identify individuals who malabsorb lactose, fructose, sorbitol and/or mannitol. Breath tests measure the amount of gas in the breath after consuming a dose of the test sugar in question.
  • The tests are based on the premise that poorly absorbed sugars are fermented by intestinal bacteria, producing gases. These gases are absorbed across the intestine, carried through the bloodstream to the lungs, exhaled and collected in the breath. If a rise in breath hydrogen or methane is detected, it is interpreted that some of the test sugar has been malabsorbed. If symptoms occur during or just after the test, then ‘intolerance’ to the sugar is reported.
  • Despite widespread use, there are several reservations about the reliability and clinical value of these tests.

Recommendations regarding breath tests:

  • Breath tests should not be used to guide dietary restrictions. Instead, patients should be encouraged to follow a 3-phased low FODMAP diet (restriction, reintroduction, personalization) to identify which sugars trigger IBS symptoms and which do not.
  • Breath tests do not diagnose disorders. Patients should not be given labels such as ‘fructose malabsorption’ or ‘fructose intolerance’.
  • Breath tests are most useful for confirming or denying the presence of lactose malabsorption, but do not necessarily indicate whether the patient is lactose intolerant. Many people can tolerate 12-15g lactose spread across the day.

Therapeutic options for management of IBS – few different approaches

Dietary/eating modifications; these aren’t the same as GERD/reflux protocols, but some overlap

  • Reduction in caffeine intake
  • Reduction in fat intake; spread throughout day is fine, but avoiding high amounts at one time is more of the issue
  • Reduction in alcohol intake
  • Avoidance of spicy foods
  • Increase in fluid intake

Modification of fiber intake

  • Fiber supplementation
    • There are many different types, from soluble, to insoluble, then further categorized into highly-fermentable, moderately-fermentable, and non-fermentable.

Modification of meal patterns and portion size

Exclusion diets

  • Restriction of fermentable carbohydrates (FODMAPs)

There are also other therapeutic approaches, like lifestyle changes, supplements, medications (that do a variety of actions to help reduce symptoms), and even psychological therapies.

FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) – Three-Phase Diet

Pathophysiology of IBS and Mechanism of FODMAP Actions

  • There are nerves that line the intestines which are overactive in IBS. As a result, normal changes in the gut (such as increases in the amount of gas and water), can be experienced as painful episodes of bloating and abdominal pain.
  • When FODMAPs are ingested, they attract water into the small intestine, causing the intestines to distend (expand) and may cause motility (movement of food) changes.
  • FODMAPs are also poorly absorbed in the small intestine, so when they reach the large intestine, bacteria use FODMAPs as an energy source to survive. The bacteria rapidly ferment the FODMAPs and produce gas as a result.
  • These actions cause an expansion of intestinal contents, stretching the intestine wall. Because people have a highly sensitive gut, ‘stretching’ of the intestinal wall can cause exaggerated sensations of pain and discomfort.

FODMAP Characteristics

FODMAPs are a group of short chain carbohydrates (or sugars) that are:

  • Small in size
  • Poorly absorbed or not absorbed at all in the small and large intestine
  • Rapidly fermented by gut bacteria

Sugars classified as FODMAPs include oligosaccharides (fructans and GOS), polyols (sorbitol and mannitol), fructose, and lactose.

Fructans and GOS

Fructans and GOS are not digested in the small intestine because humans lack the enzymes needed to break these chains of sugars into individual sugar units. Instead, these sugars pass into the large intestine where they are used as fuel by the gut bacteria (fermented), resulting in gas production. The gas produced causes the intestines to expand (distend) and causes gas in healthy people (a normal part of digestion). However, because people with IBS have a highly sensitive gut and problems regulating movements of the gut and contents within (gut motility), these changes may result in symptoms of bloating, abdominal pain/discomfort and altered bowel habit.

Sorbitol, mannitol, and fructose

The polyols (sorbitol and mannitol) and fructose are absorbed slowly along the length of the small intestine. As they move through the small intestine, they attract water into the intestine (by osmosis), causing the intestines to expand (distend). These effects also occur in the large intestine and may result in symptoms of pain and diarrhea.

These effects on the small intestine occur regardless of the extent to which they are absorbed in the small intestine.

If sorbitol, mannitol, and/or fructose are not fully absorbed in the small intestine, they spill over into the large intestine where they are used as fuel by the gut bacteria (fermented), resulting in gas production. Combined, these effects result in symptoms of abdominal pain, bloating, and altered bowel habit (diarrhea in particular).


To be absorbed, lactose must be broken into its individual sugar units by the enzyme, lactase. In the proportion of people with IBS who lack lactase, lactose reaches the large intestine undigested. Here, lactose attracts water into the large intestine and is used as fuel by the gut bacteria (fermented), producing gas. In people with lactose intolerance, the gas production can result in symptoms of bloating, wind, pain, and diarrhea (depending on the dose of lactose consumed). Lactose intolerance can be transient, so lactose tolerance can be re-tested (using an elimination-challenge approach with food or using breath tests) to determine whether tolerance improves with time.

The 3 Phases

Phase 1 – Low FODMAP intake (2-6 weeks)

Aim is to identify FODMAP sensitive individuals and induce symptom relief

  • High and moderate FODMAP foods are swapped for low FODMAP alternatives
  • Patients eat mostly low FODMAP foods in this step

Phase 2 – FODMAP reintroduction (6-8 weeks)

Aim is to identify sensitivities to individual FODMAP subgroups (excess fructose, lactose, GOS, fructans, mannitol, and/or sorbitol)

  • Patients only progress to phase 2 if they experience an adequate improvement in symptoms in phase 1
  • Background intake remains low in FODMAPs
  • Staged food challenges (using foods containing moderate and the high amounts of 1 FODMAP subgroup at a time) are used to determine which FODMAPs are tolerated, and which are not.
  • Serving sizes can be based off servings in the Monash app, or 1/3 usual serving on day 1, ½ usual serving on day 2, and full serving on day 3.
  • Some challenges (such as GOS for garlic and onions) may be better tolerated if the challenge is consumed every other day for the 3 testing days.
  • Order of FODMAPs reintroduced can be up to client preference, however individual subgroups should be tested before combined ones.

Phase 3 – FODMAP personalization (long-term)

Aim is to liberalize restrictions, expand the diet, and establish a personalized FODMAP diet for the long-term.

  • We should understand which FODMAPs are tolerated and which trigger symptoms
  • If using the Monash FODMAP app, tailor the Food Guide to suit personal FODMAP sensitivities
  • Patient includes well tolerated foods and FODMAPs in their diet, and only restricts poorly tolerated FODMAPs to a level that provides adequate symptom control.
  • Bring well-tolerated foods and FODMAPs back into the diet and restricting the diet only to a level that is absolutely necessary to maintain symptom control.
  • Ongoing challenges with poorly tolerated FODMAP subgroups are recommended as FODMAP tolerance and IBS symptoms may change over time.

It’s not meant to be a long-term diet. The goal is to move from the restriction of phase 1. While in even the first phase, it’s important to remember that this is a low FODMAP diet, not “no” FODMAP.

Quick notes on food allergies versus food sensitivities versus food intolerances

  • Food Intolerance – Non-Immunologic reaction to food; lactose-intolerance is a good example, as would other high FODMAP foods
  • Food Allergy – Immune hypersensitivity (IgE reaction)
    • Immediate responses; think peanut allergy
    • Symptoms of an IgE allergy usually appear within seconds or minutes. These symptoms can include:
      • Swelling/inflammation
      • Hives/Rash
      • Itching skin
      • Difficulty breathing
      • Throat tightening
      • Anaphylactic shock (in severe cases)
  • Food Sensitivity – Immunologic delayed reaction to food (IgG & IgA reactions)
    • Symptoms of an IgG reaction can appear up to 72 hours after eating a food.
      • Nausea
      • Bloating/gas
      • Diarrhea
      • Constipation
      • Headaches
      • Joint aches
      • Fatigue
      • Mood changes
      • Weakness
      • Brain fog/memory issues

In the past, IgG food sensitivity tests weren’t recommended due to high level of false positives from normal and expected reactions. If I am considering doing any food sensitivity testing, I use The FIT (Food Inflammation Test) by KBMO diagnostics, which measures foods, colors, and additives for IgG 1-4 and C3d complement. The multi-pathway testing measures an inflammatory pathway instead of IgG alone, which helps to eliminate false positives that occur with traditional IgG testing. Unlike food allergies, food sensitivities are typically not long-term, and may sometimes be reduced with dietary intake changes and other digestive health protocols.

The other typical option for IgG food sensitivities is traditional elimination diets.

Quick notes on Probiotics:

While there are some medical conditions where probiotics may help, this can vary between people. A summary of research suggests inconsistent benefits in digestive health over placebo. Other studies suggest no benefits on symptoms, with a variety of strains tested.

Current evidence suggests anywhere from 5-20 billion Colony Forming Units (CFUs) dose at time of production, depending on need and desired outcome.

Probiotics are generally considered safe as they naturally occur in the body and in probiotic-containing foods, however it’s important to remember they may cause mild stomach upset, diarrhea, bloating (especially when first starting to take them), as well as potentially triggering allergic reactions. They are not recommended for people who have an increased risk of infection include those with a critical illness, those with a weakened immune system (such as those undergoing chemotherapy), and those who recently had surgery. It’s recommended to always talk to your healthcare provider before starting a probiotic supplement.

As we look towards supporting digestive systems, it’s important to remember that there is never a one-size-fits-all product or diet. Digestive-related dietary changes should take a personalized approach with the help and support of a physician and licensed nutrition practitioner. For a video version of this article, check out my video here.

Sources & Resources:

  • https://www.monashfodmap.com/
    • FODMAP content and pictures used in this blog article
  • https://my.clevelandclinic.org/health/diseases/
  • https://medlineplus.gov/
  • https://www.mayoclinic.org/diseases-conditions