Supplements

Soluble fiber dissolves in water and works to normalize stool consistency. Meta-analyses show that soluble fiber, especially psyllium husk, improves global IBS symptoms, abdominal pain, and stool consistency. Additionally, soluble fiber helps support the gut microbiota. When soluble fiber is fermented, it produces short-chain fatty acids—which are compounds that support overall gut health.

Sources of soluble fiber

Soluble fiber can be found in foods such as oats, barley, legumes, and chia seeds. Many patients find it helpful to take a soluble fiber supplement to support their IBS symptoms in addition to adding soluble fiber into their diet. The soluble fiber supplement with the strongest research among patients with IBS is psyllium.

When increasing fiber (either through the diet or supplementation), it is important to start with small amounts and increase gradually to minimize any new symptoms such as gas and bloating. If you do experience these symptoms, they are usually temporary as the gut gets used to the additional fiber.

Practical tips for starting a fiber supplement

• Start with psyllium fiber. This is available as whole husks, powders (flavored or unflavored), or capsules.
• Start with half to one teaspoon of powder or husk (approximately 3-4 g of fiber). Mix with one full glass of at least 8 to 10 oz of water. Drink an additional 8 to 10 oz glass of water after. Continue with this amount for 3 days before increasing by an additional half to one teaspoon for an additional 3 days. Continue increasing psyllium by half to 1 teaspoon every 3 days to reach the desired stool consistency or until the maximum dosage.
• If the texture of psyllium is difficult to tolerate, some patients find mixing it into yogurt, applesauce, or juice to make a "psyllium jelly" can be helpful. Psyllium capsules are an alternative form to consider but have relatively low amounts of psyllium fiber compared to capsules and powders and may require consuming many (10+) capsules per day, which can be expensive.
• If using a flavored psyllium fiber, review packaging labels for potential high-FODMAP ingredients such as inulin, chicory, sorbitol, xylitol, or added fructose, which may worsen symptoms.
• If you have trouble tolerating psyllium supplementation due to symptoms, alternative soluble fiber sources to consider include partially hydrolyzed guar gum (PHGG), methylcellulose, or calcium polycarbophil.
• Avoid fiber supplements that are comprised of insoluble or highly fermentable fibers, such as wheat bran, wheat dextrin, or inulin (often found in fiber gummies), as these can worsen IBS symptoms.

The evidence and how it works

Peppermint oil is another commonly used supplement for IBS symptoms. Studies have shown peppermint oil can improve IBS symptoms, particularly abdominal pain. The most recent American College of Gastroenterology IBS management guidelines suggest the use of peppermint oil as a treatment option to provide relief of IBS symptoms.

Peppermint works by relaxing smooth muscle in the gut and may have some anti-inflammatory effects in the gut. Peppermint oil can come in many forms. The formulation with the strongest evidence is an enteric-coated microsphere preparation called IBgard that is designed to be delivered in the small intestine, where it is believed to work. In a one-month clinical trial, this peppermint oil product has been shown to improve multiple GI symptoms of IBS.

Important caveats

Commercial insurance typically does not cover peppermint oil products, and usually the cost of the product is out of pocket. Additionally, some patients report peppermint can exacerbate GERD (acid reflux) symptoms, although the enteric-coated forms are intended to reduce this risk.

How they work

Digestive enzymes are proteins that help break down food for absorption. Our digestive system produces these enzymes to break down essential nutrients like carbohydrates, proteins, and fats.

Digestive enzymes have become widely popular for treating a wide range of digestive issues. Supplementing with a digestive enzyme can help alleviate symptoms in individuals with certain gastrointestinal conditions, including IBS. However, selecting the right type of enzyme for the specific condition is imperative.

Matching specific enzymes to trigger foods

For IBS patients who are sensitive to FODMAPs, digestive enzymes targeted at breaking down FODMAPs can be helpful. While these enzymes are not a cure, they can offer more flexibility and reduce stress around eating.

Examples of specific digestive enzymes:

Fodzyme and Intoleran are two common digestive enzyme brands used by GI clinicians. Selecting a digestive enzyme is dependent on individual FODMAP intolerances and should be guided by a healthcare professional.

Evidence and clinical guidelines

Probiotic supplements are widely popular and are among the most commonly used supplements for IBS. Despite their popularity, there is limited high-quality clinical evidence supporting the widespread use of probiotics in patients with IBS. In fact, based on the available research, both the American Gastroenterological Association (AGA) and the American College of Gastroenterology recommend against the routine use of probiotics for IBS in recent management guidelines.

In clinical practice, probiotic use for IBS is highly variable based on individual patient and provider preferences. Most gastroenterology providers view probiotic supplements as one of many potential treatment options for IBS. Some patients respond well to probiotic supplements, while others experience little to no benefit from probiotic supplements.

Key considerations for trialing a probiotic

Below are some important considerations when considering a trial of probiotic supplements for IBS symptoms:

1. A minimum 4- to 8-week trial of a probiotic supplement is recommended to assess symptom improvement. If there are no significant symptom benefits, experts recommend discontinuing the probiotic supplement.
2. Specific probiotic strain selection based on individual symptoms is key. Review the packaging label of probiotic supplements to identify that the strain or strains used have evidence that shows improvement in targeted symptoms. Effects are strain-specific and do not generalize across products. For example, some brands carry multiple different probiotic products, some of which contain evidence-based strains and some of which do not.
3. Multi-strain formulations containing a specific strain may have different effects than a single-strain formulation and are not necessarily superior to single-strain formulations. For example, a probiotic supplement with eight different strains, including Lactiplantibacillus plantarum 299v, may have different effects than a single-strain formulation with only Lactiplantibacillus plantarum 299v.
4. In general, the strongest evidence for symptom improvement from probiotics has been observed in diarrhea-predominant (IBS-D) or a general IBS population (not specific to subtype). Evidence in constipation-predominant IBS (IBS-C) is limited, and no specific probiotic can be recommended for this specific population based on the data. A reasonable approach is to favor a strain that showed benefit in the general IBS population, but this approach is based on clinical reasoning rather than direct evidence.

Selecting the right strain

The table below summarizes commercially available probiotic strains with evidence to support potential benefit for IBS symptoms.

The table below reviews the evidence behind other supplements that patients may consider using for their IBS symptoms. Evidence for these supplements varies, with many of them having little to no evidence. Supplements should only be used under the direction of a healthcare professional.