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Irritable Bowel Syndrome (IBS): Diagnosis & Treatment

Written by Jasmine Foster, BS (Biology), BEd | Last updated:
Puya Yazdi
Medically reviewed by
Puya Yazdi, MD | Written by Jasmine Foster, BS (Biology), BEd | Last updated:

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Irritable bowel syndrome is a poorly-understood condition that causes pain, embarrassment, and frustration. How is it diagnosed, and what are the best ways to control it? Read on to find out.

What Is Irritable Bowel Syndrome?

Irritable bowel syndrome (IBS) is a gut condition that causes abdominal pain, bloating, and dysregulated bowel movements. The NIH estimates that as many as 20% of Americans may experience signs of IBS, but doctors still don’t know the exact causes behind this syndrome [1].

There are two main types of IBS – one that involves Diarrhea (IBS-D) and one that involves Constipation (IBS-C).

The large intestine is loaded with bacteria, but the rest of the gastrointestinal tract has relatively few bacteria under normal conditions. When a person has bacteria in the small intestine, unabsorbed carbohydrates are fermented there, producing significant amounts of gas.

This can cause cramping and burning because the gas stretches the small intestine. The gas can also push the intestinal content rapidly toward your large intestine to cause diarrhea. Bacteria generally ferment in the small intestines when gut ‘flow’ (motility/peristalsis) is slowed down in this area [2, 3].

IBS is a gut condition that causes abdominal pain, bloating, and dysregulated bowel movements.

How is IBS Diagnosed?

There is no definitive test for IBS. The two central symptomatic requirements for a diagnosis of IBS are abdominal pain and disturbed defecation (typically either diarrhea or constipation, though sometimes both by turns) [4].

If you suspect that you have IBS, your doctor will ask questions and perhaps perform tests to determine whether you fit into the broad diagnostic criteria for the condition, which may include [4]:

  • Abdominal pain or discomfort for at least 3 days/month in the last 3 months
  • Pain that is relieved after a bowel movement
  • Pain associated with a change in stool frequency
  • Pain associated with a change in stool consistency (either diarrhea or constipation, typically)

Your doctor may also attempt to determine whether any of the following may apply to you [4]:

  • Disrupted gut flora (due to recent infection and antibiotics, for example)
  • Visceral hypersensitivity
  • Food intolerance
  • Carbohydrate malabsorption
  • Other gut disruptions

Individual cases of IBS are generally classified as IBS-D (diarrhea predominant), IBS-C (constipation predominant), or IBS-M (mixed diarrhea and constipation). Based on the totality of symptoms and test results, your doctor will recommend a treatment and management plan.

IBS is typically diagnosed by ruling out other explanations for gastrointestinal symptoms.

How is IBS Treated?

Doctors generally prefer not to medicate IBS unless strictly necessary. As such, a series of management strategies have been developed which your doctor or nutritionist may recommend.

Dietary Interventions

Low FODMAP Diet (Possibly Effective)

Some nutritionists recommend a low FODMAP diet to help control the symptoms of IBS. FODMAPs are a group of carbohydrates which, in the last decade or so, have been identified as some of the prime suspects behind irritable bowel syndrome, or IBS. FODMAPs is a catchy acronym that stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, And Polyols [5, 6, 7].

The major FODMAPs include [5, 6]:

  • Fructose
  • Lactose
  • Fructans and galactans
  • Galacto-oligosaccharides (GAS)
  • Polyols (sugar alcohols, or any sweetener that ends with -ol)

Despite their potential benefits, FODMAPs may produce (or at least worsen) symptoms in people with IBS [8, 9].

For more about the low FODMAP diet, check out this post on how it works and this post on which foods are included.

A low FODMAP diet is an elimination diet that tests your reaction to different carbohydrates and cuts problematic ones out of your diet permanently.

Other Elimination Diets

The low FODMAP diet is one type of elimination diet; your doctor or nutritionist may guide you through another type of elimination diet if they suspect that your IBS is being triggered or worsened by foods other than FODMAPs. Some substances that may worsen IBS include carbonated beverages, spicy foods, alcohol, caffeine, excess fats, dairy, and gluten [10].

Elimination diets can be tricky to pull off without exacerbating the risk of nutrient deficiencies. We strongly recommend consulting a doctor, nutritionist, or dietitian before attempting one yourself.

Very Low Carb Diets

Some people with IBS-D (predominant diarrhea) may benefit from strictly limiting their carbohydrate intake, though very little clinical evidence is available. In one study of 17 patients, pain scores and measures of quality of life significantly improved after 4 weeks of a very low carb diet (VLCD). The study did not provide follow-up data, so it’s unclear whether the benefits persisted or whether the participants continued to eat a VLCD after the study was complete [11].

As always, we recommend working with a doctor or nutritionist to design the ideal management diet for you.

Lifestyle Changes

In order to control the symptoms of IBS and improve your quality of life, your doctor may recommend a few lifestyle changes. If your doctor has prescribed medication, however, these strategies should never be used in place of those prescriptions.

Exercise

Moderate exercise (and improved physical fitness) is among the best remedies for gut inflammation and overall health. According to many studies, physical activity actually changes the composition of the gut flora, resulting in an increase of beneficial species. Multiple studies have also found that an exercise regimen improved IBS symptoms specifically [10].

The key may be to ensure that physical exertion remains within your (or your intestines’) comfort zone. Vigorous physical activity, such as extensive running, may stress the intestines, leading to so-called “runners’ trots.” However, moderate physical activity appears to improve transit time and help regulate bowel movements [10].

Hydration

It’s very important to make sure you are drinking enough water: dehydration has been found to significantly worsen the symptoms of IBS. Regardless of your symptoms, many experts recommend drinking 8 glasses of water per day, but a lot of research suggests that actual water requirements fluctuate hugely from day to day [10, 12].

If you are constipated, you may want to increase your water intake to see if that improves some of your IBS symptoms [13].

Stress Reduction

Psychological stress is widely believed to trigger or worsen IBS. In fact, some researchers refer to both “irritable bowel” and “irritable brain” as equal factors in the development of IBS. Furthermore, anxiety and frustration with gut symptoms can further worsen these same symptoms. As such, many experts recommend stress management strategies as part of a holistic strategy to manage and treat this condition [14, 15, 16].

Meditation

One specific stress reduction technique with evidence to support its use in IBS is meditation. In a study of 75 IBS patients, mindfulness meditation significantly reduced reported IBS symptoms. In two studies of a total of 232 patients, a type of relaxation training similarly reduced symptom severity, in some cases significantly better than conventional therapies [17, 18, 19].

While stress-busting therapies certainly can’t hurt, they should never be used in place of something your doctor recommends or prescribes.

Psychological stress and intestinal symptoms appear to form a feedback loop in IBS, where each one can worsen the other. As such, stress reduction techniques are often recommended for IBS patients.

Supplements for IBS

The FDA has not approved any natural substances for medical use in IBS, and supplements generally lack solid clinical research. Speak with your doctor before using any of these substances.

Likely Effective

1) Peppermint

Peppermint is among the best-known and -studied natural remedies for IBS, and it has a significant chunk of evidence to back up its use. A meta-analysis of twelve studies and 835 patients found that peppermint oil reduced abdominal pain and other symptoms of IBS without adverse effects [20].

Peppermint oil contains monoterpene compounds which are believed to be responsible for its effects on IBS symptoms [20].

Up to 80% of IBS cases may be caused by small intestinal bacterial overgrowth (SIBO). Peppermint oil reduced intestinal hydrogen gas production in patients with bacterial overgrowth. It also reduced IBS symptoms related to abnormal intestinal gas production [21].

According to multiple studies, peppermint oil may reduce abdominal pain and other symptoms of IBS.

Possibly Effective

2) Probiotics & Fermented Foods

One of the most likely causes of IBS is dysregulation of the gut flora. In fact, individuals with IBS often appear to have decreased diversity and numbers of beneficial microbiota and protective strains such as L. reuteri [22].

Probiotic supplements are therefore promising strategies for managing IBS. Multiple probiotic species have produced promising clinical results, including:

  • Bifidobacterium infantis [23]
  • Bifidobacterium lactis [24]
  • Bacillus coagulans [25]
  • Saccharomyces cerevisiae (Brewer’s yeast) [26]

Fermented foods are a great way to increase your intake of diverse probiotic bacteria without the use of supplements. Consuming fermented milk products (which include buttermilk, cheese, yogurt, kefir, sour cream, and more) significantly improved symptoms of IBS in multiple clinical trials [27, 28].

Another fermented food with promise for IBS is sauerkraut (a type of fermented cabbage) [29, 30].

Because the microbiome of people with IBS is often dysregulated, researchers are looking into whether probiotic supplements and fermented foods can help control symptoms. Early results have been promising.

3) Anise

In a trial of 120 IBS patients, anise oil (200 mg, 3 times daily for 4 weeks) improved the symptoms of IBS (abdominal pain, bloating, and reflux) better than peppermint oil and placebo [31].

This result was promising, but needs to be reproduced. Future studies will determine the role of anise in IBS management.

4) Psyllium Husk

Psyllium husk has improved both diarrhea and constipation in clinical settings [32].

In one study of 28 subjects, psyllium husk eliminated symptoms of IBS, and stopping psyllium husk resulted in a relapse [33].

A meta-analysis of psyllium and other strategies in IBS found that patients taking psyllium were more likely to report symptom improvement than those taking a placebo. Furthermore, the number of adverse events associated with psyllium husk was determined to be insignificant [34].

Psyllium is considered a safe source of beneficial fiber for IBS. If your doctor recommends increasing fiber intake, ask them if psyllium could be right for you.

5) Guar Gum

Guar gum is a complex sugar (polysaccharide) made from legumes called guar beans. Because of its thickening and stabilizing properties, it is used as a food additive and a filler in many processed foods [35].

As a galactomannan polysaccharide, guar gum is fermented for energy by healthy gut flora. As such, guar gum may promote the growth of beneficial bacteria in the gut, thereby suppressing IBS. In a study of 188 IBS patients, 5 g/day of guar gum significantly reduced discomfort and improved bowel habits. Furthermore, patients were more likely to choose to keep taking guar gum than to switch to a wheat bran diet after four weeks [36, 37, 38].

Guar gum is another safe source of beneficial fiber for IBS. If your doctor recommends increasing fiber intake, you may want to consider guar gum for this purpose.

6) Wheat Bran

Yet another source of fiber a doctor or nutritionist may recommend is wheat bran, which is made from the hard outer layers of the wheat grain. Eating a diet rich in wheat bran (30 g per day) was found to decrease abdominal discomfort and improve bowel habits in 188 IBS patients. However, the wheat bran diet was not as effective as guar gum, and fewer patients reported satisfaction with wheat bran than with guar gum [37].

Furthermore, people with dietary restrictions may not be able to eat wheat bran. It can be a healthy source of dietary fiber for some, but we recommend discussing this and other fiber supplement options with your doctor to choose the best one for you.

7) Soy Isoflavones

Soy isoflavones are polyphenols extracted from soybeans. They are structurally similar to estrogen and are believed to activate estrogen receptors found in the colon. Because of this action, they have been studied for their potential to affect smooth muscle activation in the gut [39].

In one study of 100 women with IBS, supplementing with soy isoflavones improved measures of symptom severity and quality of life, though the improvement was only significant when symptom severity and quality of life scores were combined [39].

Some women with IBS may benefit from soy isoflavones, though other options are likely to be more effective.

Insufficient Evidence For

The following substances have shown promise against IBS in limited, low-quality clinical studies; there is currently insufficient evidence to support their use in this context, and they should never replace what your doctor prescribes. Remember to talk to your doctor before starting any new supplement or making significant changes to your diet.

8) Curcumin

Curcumin, a polyphenol found in turmeric, is one of the most popular natural anti-inflammatory supplements on the market. In multiple small clinical studies, curcumin reduced the symptoms of IBS; however, placebo-controlled trials are lacking [40, 41].

9) Aloe Vera

Aloe vera, best known as a skin softener and a remedy for burns, may also help soothe the gut. A meta-analysis of three studies and 151 IBS patients found that those who took aloe vera experienced improvements in their symptoms compared to those taking a placebo. The analysis also found no significant adverse effects [42].

10) Zinc

Both zinc deficiency and over-supplementation have been implicated in gut disease, so it’s important to get the balance right. If your doctor determines that you could be deficient, then it may be appropriate to supplement. Otherwise, it may be better to simply eat more zinc-rich foods [43].

The best sources of zinc are meat, fish, and especially shellfish like oysters. Breakfast cereals are often fortified with zinc, and legumes have some as well, but vegetarians are generally more susceptible to zinc deficiency than omnivores [43, 44].

11) Artichoke Leaf Extract

Artichoke leaf extract is obtained from globe artichoke (Cynara scolymus) or cardoon (Cynara cardunculus) plants. Some evidence from clinical studies may support its traditional use for gut problems: in two studies of a total of 487 IBS patients, those taking artichoke leaf extract reported significant improvements in their symptoms, including more consistent bowel movements. In one of these studies, almost all participants rated artichoke leaf extract’s effectiveness as at least equal to other therapies they had tried [45, 46].

12) Berberine

Berberine is a compound found in several different plants, including Barberry (Berberis vulgaris), Oregon Grape (Mahonia aquifolium), Goldenseal (Hydrastis canadensis), and Chinese goldthread (Coptis chinensis). It has a 3000-year history of use in traditional Chinese and Indian medicine [47].

In one study of 196 patients with IBS-D (diarrhea predominant), those who received berberine hydrochloride reported less diarrhea, abdominal pain, and urgent defecation than those who took the placebo. Furthermore, the patients’ quality of life appeared to improve, based on surveys intended to measure anxiety and depression [48].

13) Glutamine

Glutamine is the most abundant amino acid in the body. The naturally occurring form and the form that our body uses is L-glutamine [49].

In a study of 106 IBS patients who had recently had an enteric infection, those taking glutamine supplements reported a significant reduction in the severity of their symptoms. It is unclear whether glutamine supplementation could be helpful to patients not fitting the description of this study, however [50].

14) Butyrate

Butyrate is a short-chain fatty acid (SCFA). Fatty acids are the building blocks of fats that our cells need to function. Butyrate is made when the bacteria living in our guts ferment otherwise indigestible fibers from grains, beans, onions, bananas, and other foods rich in complex carbs [51, 52, 53].

Butyrate supplements (in the form of sodium butyrate) have shown promise in reducing the severity of IBS symptoms. In one study of 66 patients, those taking butyrate reported less pain during bowel movements. Another report found that butyrate improved the regularity of bowel movements in IBS patients [54].

These results are early, but unsurprising; according to one study, people with IBS are more likely to have dysregulated gut flora that produces less butyrate than the gut flora of healthy people [55].

Butyrate is a beneficial short-chain fatty acid produced by the healthy gut flora. People with IBS may produce less.

Medications

If your IBS symptoms do not improve after lifestyle and diet changes, your doctor may prescribe medication to help improve your quality of life. We strongly recommend against taking any of these medications without a doctor’s prescription.

Medications that may be prescribed for certain cases of IBS include:

  • Fiber supplements (e.g. Metamucil) [56]
  • Laxatives (e.g. magnesium hydroxide or polyethylene glycol) [57, 56]
  • Anti-diarrheal medications (e.g. loperamide) [56]
  • Anticholinergic medications (e.g. dicyclomine) [56]
  • Tricyclic antidepressants (e.g. imipramine) [56]
  • SSRI antidepressants (e.g. fluoxetine) [56]
  • Pain medications (e.g. pregabalin or gabapentin) [57]
  • Muscle relaxants (e.g. alosetron or eluxadoline, specifically approved for IBS) [56]
  • Antibiotics (e.g. rifaximin, specifically approved for bacterial overgrowth in IBS) [56]

Takeaway

Irritable bowel syndrome (IBS) is a gut condition that causes abdominal pain, bloating, and dysregulated bowel movements. It is usually classified as IBS-D (diarrhea predominant), IBS-C (constipation predominant) or IBS-M (mixed). To diagnose IBS, doctors typically measure the frequency of abdominal pain and determine whether the pain is associated with intestinal pathology. Then, doctors recommend a treatment and management plan.

These management plans usually include changes to diet and lifestyle. Most doctors recommend exercise, stress reduction, and ensuring adequate hydration. Many will then recommend diets that eliminate trigger foods (usually with a reintroduction step to check for a reaction).

In addition to diet and lifestyle management, many supplements have been investigated for potential use in IBS. Peppermint is the best-known and best-studied so far, though probiotics, anise, psyllium, guar gum, wheat bran, and soy isoflavones have also shown promise.

If a patient does not respond well to diet, lifestyle, and supplements, doctors may prescribe some medications to help control symptoms and improve quality of life.

Further Reading

About the Author

Jasmine Foster

Jasmine Foster

BS (Biology), BEd
Jasmine received her BS from McGill University and her BEd from Vancouver Island University.
Jasmine loves helping people understand their brains and bodies, a passion that grew out of her dual background in biology and education. From the chem lab to the classroom, everyone has the right to learn and make informed decisions about their health.

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