Irritable Bowel Syndrome
Irritable bowel syndrome (IBS) is the most common functional gastrointestinal disorder. It is the number one reason for a gastroenterology visit. IBS affects between 25 and 45 million people in the United States (10 to 15% of the population). About 2 in 3 IBS sufferers are female. IBS affects people of all ages, even children.
What are the different types of IBS?
There are 3 main types of IBS but 4 types in total. These are:
- IBS with predominant diarrhea
- IBS with predominant constipation
- IBS with mixed (constipation and diarrhea)
How is IBS diagnosed?
The diagnosis of IBS is difficult because there are no specific tests to identify the disease. We rely on symptoms that are non-specific. These symptoms often resemble symptoms of other serious conditions like colitis. Experts say that IBS is not a diagnosis of exclusion and that the diagnosis should be based on symptoms. This is not often reassuring to patients that are scared, have family members with cancer or IBD or patients that have previously suffered from a misdiagnosis or delayed diagnosis. For these patients; no testing at all is not an option. For some of these patients, a negative result from tests is reassuring.
The Rome IV criteria for the diagnosis of IBS are recurrent abdominal pain, on average, at least 1 day/week in the last 3 months, associated with two or more of the following criteria:
- Related to defecation.
- Associated with a change in frequency of stool.
- Associated with a change in form (appearance) of stool.
The criteria should be fulfilled for the last 3 months but symptoms should be present at least 6 months before diagnosis.
Key to diagnosis
- Physical examination
- ESR, CRP, and fecal calprotectin in patients with persistent diarrhea. If positive, a colonoscopy may be warranted.
- Celiac panel in patients with persistent diarrhea. If positive, a colonoscopy may be warranted.
- Thyroid function test in appropriate individuals.
- Stool studies in patients with persistent diarrhea and other features (e.g. travel history) to rule out infection or infestation.
- Screening colonoscopy in age-appropriate persons if not previously done.
- Diagnostic colonoscopy with random biopsies in patients with persistent diarrhea despite therapy.
- Empiric therapy for bile acid malabsorption in suspected cases.
- Breath test to rule out carbohydrate malabsorption in certain patients with persistent IBS with diarrhea despite treatment.
- A test is not required to make the diagnosis of IBS.
What causes IBS?
The exact cause of IBS is unknown. The following pathophysiologic mechanisms have been proposed:
- Abnormal motility: IBS patients appear to have an abnormal movement of the gut especially after a meal.
- Visceral hypersensitivity: Patients with IBS have altered thresholds to pain within the GI tract.
- Role of infection: About 10% of IBS patients develop the symptoms after experiencing infectious gastroenteritis. Salmonella, Shigella, and Campylobacter are usually involved but any infection including viral infection can be involved.
- Role of inflammation: Inflammatory cells are sometimes seen in patients with IBS even in the absence of infectious gastroenteritis.
- Role of bacterial overgrowth: IBS patients experience excessive fermentation and increased small bowel gas formation. Some patients with IBS with diarrhea have improvements in symptoms with antibiotics. All of these point to a potential role of small intestinal bacterial overgrowth (SIBO) in IBS.
- Role of serotonin: The guts of patients with IBS contain low amounts of serotonin, the enzyme that synthesizes it, as well as a transporter that brings serotonin into cells.
- Role of the brain-gut axis interaction: Disruption of the brain-gut communication has been implicated in IBS. Stress acts on the emotional limbic system leading to increased release of adrenocorticotropic hormone and cortisol. This leads to symptoms of IBS.
- Role of the microbiota: Fecal analysis showed that people with IBS have an altered gut microbiota. They have more of the phylum Firmicutes and fewer of Bacteroidetes.
10 Myths about IBS
Myth 1: IBS is a psychological disorder. It’s just all in your head.
The Truth: IBS is a real disease. It is a functional disorder with no specific disease marker or diagnostic test.
Myth 2: IBS is just a minor bother.
The Truth: IBS patients feel miserable. IBS can affect all aspect of their lives. The economic impact of IBS is huge from reduced productivity, days off work, physician office visits, hospital visits, and diagnostic tests.
Myth 3: IBS is similar to IBD (inflammatory bowel disease).
The Truth: IBS is completely different from inflammatory bowel disease (ulcerative colitis or Crohn’s disease). There are specific tests for the diagnosis of IBD but not IBS. Unlike IBD, IBS do not cause bloody stool or anemia. IBS do not lead to surgeries.
Myth 4: I have IBS. Treatment that works for someone will also work for me.
The Truth: No two IBS patients are the same. Treatment that works for one individual will not necessarily work for another. Treatment should be individualized.
Myth 5: All patients with IBS should be on gluten free diet.
The Truth: Some patients with IBS may have symptoms from food that contain gluten but complete avoidance of gluten should not be undertaken without consulting with a physician. IBS is different from celiac disease, a disease that requires complete abstinence from gluten.
Myth 6: IBS patient should not eat this particular food.
The Truth: Patients with IBS benefit from low FODMAP diet but there is no particular food that an IBS patient should avoid forever.
Myth 7: There is a test for IBS.
The Truth: There is no specific test for IBS yet. The diagnosis is based on symptoms and the exclusion of other diseases.
Myth 8: IBS can lead to cancer.
The Truth: IBS do not lead to cancer.
Myth 9: IBS is caused by anxiety and depression.
The Truth: What causes IBS is unclear. Several possible causes have been proposed. IBS patients may suffer from anxiety and depression but they are not the cause of IBS.
Myth 10: IBS do not affect men.
The Truth: IBS affect both men and women. IBS affects women more.
- Lifestyle modification: exercise, stress reduction (yoga, meditation), sleep hygiene.
- Psychological therapies: psychotherapy, hypnotherapy.
- Dietary fiber: soluble fiber (psyllium or ispaghula husk) appear to be beneficial compared to insoluble fiber (bran). Certain forms of fiber especially bran can exacerbate bloating, distention and flatulence.
- Dietary restrictions: Low FODMAP diet is the main diet for IBS. Some patients also report improvement with gluten free diet.
- Medications: multiple medications have been approved by the FDA for symptoms of IBS.
- Stool transplant: experimental.
Treatment of Symptoms of Irritable Bowel Syndrome
|Symptom||Therapy||Drug and dose|
|Diarrhea||Opioid agonists||Loperamide 2 - 4mg; when necessary titrate up to 16 mg/d|
|Diet||Low FODMAP diet
low or no gluten diet
|Bile salt sequestrants||cholestyramine (9 g bid - tid)
colestipol (2 g qd - bid)
colesevelam (625 mg qd - bid)
|Probiotics||Multiple products available|
|Antibiotics||Rifaximin 550 mg tid X 14 days|
|5-HT3 antagonists||Alosetron (0.5 - 1 mg bid)
Ondansetron (4 - 8 mg tid)
Ramosetron 5 mg qd
|Mixed opioid agonists/antagonists||Eluxadoline 100 mg bid|
|Constipation||Psyllium||up to 30 g/d in divided doses|
|Polyethylene glycol (PEG) e.g. Miralax||17 - 34 g/d|
|Chloride channel activators||Lubiprostone, 8 mg bid|
|Guanylate Cyclase C agonists||Linaclotide 290 mcg qd|
|Abdominal pain||Smooth muscle antispasmodics||dicyclomine (10-20 mg qd-qid)
Otilonium (40 80 mg bid tid)
Mebeverine (135 mg tid)
|Peppermint oil||Enteric-coated capsules, 250-750 mg, bid-tid|
|Tricyclic antidepressants||Desipramine (25-100 mg qhs)
amitriptyline (10-50 mg qhs)
|SSRIs||paroxetine (10 40 mg qd)
sertraline (25 100 mg qd)
citalopram (10 40 mg qd)
|SNRI||Duloxetine 30-90mg qd; Venlafaxine 150mg qd|
What is low FODMAP diet?
FODMAP stands for :
F: Fermentable. These foods can be broken down by bacteria in your intestine.
O: Oligosaccharides. Examples are onions, soybeans, leeks, asparagus.
D: Disaccharides. Examples are lactose in milk and diary products; sucrose in table sugar.
M: Monosaccharides. Examples are fructose in apple and honey.
P: Polyols. Examples are sorbitol and maltitol in sugar-free gums and mints.
Low FODMAP Diet for IBS
|Food Category||High FODMAP foods||Low FODMAP food alternatives|
|Breads and cereal||Rye, wheat-containing breads, wheat-based cereals with dried fruit, wheat pasta||Gluten-free bread and sourdough spelt bread, rice bubbles, oats, gluten-free pasta, rice, quinoa|
|Vegetables||Asparagus, artichokes, onions(all), leek bulb, garlic, legumes/pulses, sugar snap peas, onion and garlic salts, beetroot, Savoy cabbage, celery, sweet corn||Alfalfa, bean sprouts, green beans, bok choy, capsicum (bell pepper), carrot, chives, fresh herbs, choy sum, cucumber, lettuce, tomato, zucchini.|
|Protein sources||Legumes/pulses||Meats, fish, chicken, Tofu, tempeh|
|Fruits||Apples, pears, mango, nashi pears, watermelon, nectarines, peaches, plums||Banana, orange, mandarin, grapes, melon|
|Milk and dairy||Cow’s milk, yoghurt, soft cheese, cream, custard, ice cream||Lactose-free milk, lactose-free yoghurts, hard cheese|
|Nuts and seeds||Cashews, pistachios||Almonds (<10 nuts), pumpkin seeds|
|Biscuits (cookies) and snacks||Rye crackers, wheat-based biscuits||Gluten-free biscuits, rice cakes, corn thins|
|Seasonings and Condiments||blueberry jam, grape jelly, pickles, relish, onion powder, garlic powder||rosemary, sage, soy sauce, thyme, turmeric, vanilla, pepper, chili, curry, basil, nutmeg, parsley, paprika, turmeric, wasabi, strawberry jam|
|Sweeteners||mannitol, sorbitol, maltitol, agave, honey||aspartame, saccharine, maple syrup|
How does FODMAP cause symptoms?
FODMAP are carbohydrates that are difficult to digest. They are fermented by gut bacteria leading to gas and bloating. The pull too much water causing diarrhea or too little water causing constipation.
Can low FODMAP diet help treat IBS?
Yes. Multiple studies show improvement in symptoms of IBS with low FODMAP diet. About 75% of IBS patients that follow the diet report improvement in their symptoms.
How to be on the low FODMAP diet
There are 2 phases to the low-FODMAP diet; the elimination phase and the re-introduction phase.
Elimination Phase: This is where you eliminate all high-FODMAP foods from your diet. This should be done in consultation with your physician and/or dietician. This phase usually lasts 2-6 weeks. You should feel at least 50% better before starting the re-introduction phase. If you do not feel better at all with the low FODMAP diet, discuss this with your physician.
Reintroduction Phase: After the elimination phase, you can start re-introducing individual high-FODMAP food back into your diet. You have to add high-FODMAP food one at a time to see if the food lead to symptoms (belly ache, bloating, gas, distention, diarrhea, constipation). If the food causes symptoms, it is eliminated forever. If it does not cause symptoms, then you can continue to eat it. You should wait for at least 48 hours to assess symptoms and before adding another food back. You should add as many foods as possible back into your diet without bringing back symptoms. If you are able to eat some high FODMAP diet alongside low FODMAP diet, your diet is now a modified low-FODMAP diet.
IBS and Probiotics
Yogurt and Probiotics
|Yogurt Brands||Bacteria Strains|
|Stonyfield Farms||Lactobacillus bulgaricus
Bifidobacterium lactis DN-173 010 in Activia
Lactobacillus casei DN-114- 001 in DanActive
|Yakult||Lactobacillus casei Shirota|
|Greek gods Yogurt||Lactobacillus bulgaricus
|La Yogurt||Lactobacillus bulgaricus
Bifidobacterium animalis BB12
|Voskos Greek Yogurt||Lactobacillus bulgaricus
Patient Information Brochure on Irritable Bowel Syndrome [PDF and Printable]