Updated February 2021
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Understanding Irritable Bowel Syndrome
Irritable bowel syndrome (IBS) is diagnosed when someone has been experiencing abdominal pain, bloating, and unusual bowel movements for more than six months, and when diseases with overlapping symptoms, such as Crohn’s disease or inflammatory bowel disease, have been ruled out. There’s no biomarker or pathology for IBS—the intestine and blood tests look normal. Although there are treatments to help alleviate the symptoms, we do not know the underlying causes of the chronic symptoms, and we do not have a cure for the syndrome. Treatment largely consists of managing symptoms with diet and lifestyle changes and, if necessary, medication. Not understanding what is causing symptoms and the lack of effective treatment options make this condition frustrating for patients and practitioners. In the past, the lack of diagnostic lab tests that could verify IBS led to underdiagnosis and misunderstanding. But now, using symptoms as diagnostic criteria is accepted by the medical community (Mayo Clinic, 2019).
Primary Symptoms of IBS
Do you have abdominal pain or cramping that’s associated with a bowel movement? This is the hallmark symptom of IBS, along with bowel movements that are unusual in frequency—less than three per week or more than three per day. Some people experience IBS with constipation, some people have diarrhea, and some have alternating constipation and diarrhea. (You can see the complete spectrum of stool firmness for yourself on the Bristol stool scale.) Gas and bloating are very common, and there can also be mucus in the stool and a feeling that a bowel movement was incomplete.
For women, symptoms can be affected by hormonal status: You might have diarrhea before menstruation and constipation during menstruation.
How Many People Are Affected by IBS?
IBS is surprisingly common: 5 to 15 percent of people may have this condition. It typically occurs in younger adults and is more common in women than in men (Ford et al., 2014).
Potential Causes of IBS and Related Health Concerns
We don’t yet understand what causes IBS, and there are likely multiple causes, just as there are multiple ways that IBS can manifest. Genetic, environmental, and psychological factors can affect the risk of developing IBS. IBS frequently develops following gastrointestinal (GI) infections. Stress and physical and/or sexual abuse early in life may play a role in causing IBS, as may depression and anxiety. Its onset can be triggered by food intolerances and chronic stress, among other things (Lacy et al., 2016; Ford et al., 2014; National Institute of Diabetes and Digestive and Kidney Diseases [NIDDK], 2017).
The Gut-Brain Axis
It’s speculated that in IBS, the brain may be sending inappropriate signals to the gut or responding inappropriately to signals from the gut. For example, food may be made to move through the intestine too quickly or too slowly. Or what appears to be a normal amount of gas or stool may provoke abdominal pain (NIDDK, 2017).
One thing that comes up a lot when trying to explain IBS symptoms is too much gas (methane and hydrogen), which can cause bloating and other symptoms. There is evidence that some people with IBS produce more gas compared to people without IBS (Ong et al., 2010). Some people with IBS may not produce excessive gas, but they don’t pass it efficiently, so they may retain gas and have measurable abdominal bloating (Serra, Azpiroz, & Malagelada, 2001). Passing gas requires “housekeeping” contractions of the gut in between meals. Some people with IBS appear to have fewer of these contractions and, therefore, may be less able to pass gas. We don’t usually think about the intestine being muscular, but it is a long muscular tube, and the muscular walls need to contract and relax in a rhythmic and coordinated manner to push the contents at just the right speed.
Gut Bacteria and Gas
Our intestinal cells don’t make gas—it comes from intestinal bacteria fermenting foods that we eat. One explanation for IBS is that bacteria are located in a part of the intestine where they are not supposed to be. Bacteria should mostly reside in the colon (large intestine), the part of the intestine furthest from the stomach. There, they don’t have access to most of the food we eat, since it has already been digested and absorbed in the small intestine. In some cases of IBS, bacteria can be found in the small intestine in unusually high numbers. In the small intestine, bacteria have access to all sorts of food, and when they ferment it, they create gas and sometimes diarrhea. If the gas they make is methane, this may cause constipation (Lacy et al., 2016). More information about small intestinal bacterial overgrowth (SIBO) can be found in the conventional treatments section below.
Foods That Could Contribute to IBS
Many food sensitivities can mimic or exacerbate IBS symptoms. Problematic foods may include dairy, sugar, fruit juices, wheat, caffeine, fruits, vegetables, sweetened soft drinks, and chewing gum. (We’ll talk more about these foods in the dietary changes section.) Wheat, for example, may cause inflammation in the body even in people without celiac disease. They can be intolerant of gluten itself or other components in wheat. The symptoms of wheat or gluten sensitivity may overlap with those of IBS. More information on gluten and wheat sensitivity can be found in our article “Celiac Disease and Gluten Sensitivity.”
Another issue is that we may not digest or absorb a food completely, so a significant portion of it passes through the small intestine, reaching the large intestine, where resident bacteria may use the food and create gas, diarrhea, and irritating substances. This is what happens in lactose intolerance, which should be ruled out before diagnosing IBS. Most adults do not make much of the enzyme lactase, which digests the sugar in milk, called lactose. Undigested lactose and the water it’s dissolved in result in loose stool. Colonic bacteria also ferment the lactose, making gases and substances that irritate the gut. All of this leads to diarrhea, gas, cramps, and bloating. We usually think of lactose intolerance as chronic, but it can manifest temporarily during an illness, such as the flu (Cozma-Petruţ, Loghin, Miere, & Dumitraşcu, 2017).
Recent research suggests that intolerance of table sugar, or sucrose, may also be causing symptoms attributed to IBS. A deficiency of the enzyme that digests sucrose, called sucrase, was found in 35 percent of IBS patients in one study (S. B. Kim, Calmet, Garrido, Garcia-Buitrago, & Moshiree, 2019). Both of these enzymes, lactase and sucrase, are available commercially as supplements, but it is not clear how helpful the supplement forms are.
Fructose is another common sugar that may cause diarrhea, gas, pain, and bloating when it is not completely absorbed. This is why drinking apple juice frequently results in diarrhea in children. Fructose is a simple sugar that does not need to be broken down through digestion. However, large amounts of fructose can overwhelm the absorptive process and pass intact to the colon. Incomplete absorption of fructose has been reported in significant numbers of people with IBS (Y. Kim & Choi, 2018).
Do Prebiotic Foods Cause IBS Symptoms?
For unknown reasons, some foods and fibers that are good prebiotics—food for our gut bacteria—cause intestinal discomfort in certain people. Our gut bacteria typically like to eat the foods that the small intestine is incapable of utilizing, such as fibers in beans and vegetables. The optimal amounts and types of vegetables and fibers that promote healthy bacterial growth but do not cause excess gas and other symptoms vary from person to person.
Leaky Gut and Increased Intestinal Permeability in IBS
Some people with IBS may have a gut barrier that is not working properly to keep bacteria and undigested food components from getting into the body. If intestinal cells do not form a tight barrier, toxins and allergens can enter the body and are thought to contribute to symptoms and the severity of IBS as well as low-grade inflammation. Testing for leaky gut involves ingesting two sugars, lactulose and mannitol, and measuring them in the urine. Mannitol should be absorbed and then excreted in the urine, but lactulose should not get inside the body and show up in the urine unless you have leaky gut (Zhou, Zhang, & Verne, 2009; Linsalata et al., 2018).
Other Health Concerns Related to IBS
Although IBS can be painful, it does not appear to damage the GI tract, and it’s said not to cause other medical conditions (NIDDK, 2017). However, migraine headaches, fibromyalgia, painful bladder syndrome, and painful intercourse tend to occur together with IBS (Lacy et al., 2016).
How IBS Is Diagnosed
Diagnosing IBS is not straightforward because there aren’t any blood tests, scans, or biopsies to be used—the GI tract looks normal in IBS. Other conditions that may have similar symptoms need to be ruled out, including inflammatory bowel disease, celiac disease (gluten intolerance), microscopic colitis, bile acid malabsorption, lactose and fructose intolerances, and diarrhea due to infections (Lacy et al., 2016). Diagnosis is made purely on the basis of symptoms and the absence of other conditions with similar symptoms.
The Rome IV Criteria
Some physicians use the Rome IV criteria when diagnosing IBS. These criteria define IBS as recurrent abdominal pain or discomfort (occurring at least one day a week for the past three months), associated with two or more of the following:
• The pain improves with a bowel movement.
• When the pain began (at least six months prior), it was associated with a change in the frequency of bowel movements.
• When the pain began, it was associated with a change in the form (appearance) of stool (Mayo Clinic, 2019a).
Dietary Changes for IBS
For symptom relief, many dietary suggestions are well worth trying. Certain foods can cause IBS-like symptoms or exacerbate IBS, and these effects are mediated in many cases by the gut microflora.
The Role of Fibers in IBS
Some kinds of fiber are very helpful for some people, and other kinds make the situation worse. Several clinical studies have reported that psyllium seed husk fiber (e.g., Metamucil, also called ispaghula) can be helpful in reducing symptoms of IBS. Bran fiber, on the other hand, is not helpful—it might even make things worse (Ford et al., 2008).
Fibers are by definition substances that humans don’t digest or absorb. Some are used by the bacteria in the large intestine and some are not. If neither humans nor our resident gut bacteria can use a fiber, it will be a good bulking agent for promoting regularity; examples are the cellulose in veggies, wheat bran, and psyllium seed husk. Fibers that bacteria do use include inulin and fructoligosaccharides, which are found in garlic, onions, and other vegetables (McRorie & McKeown, 2017). For many people, consuming fibers that bacteria can use is a good thing—we want to feed our friendly gut microbial community and encourage them to make butyric acid, a great food for our intestinal cells. However, too much food for bacteria may be problematic in IBS. How the gut reacts to all these foods and fibers can be quite individual. If your gut rumbles after eating inulin or fructooligosaccharides, listen to it.
Vocab Time-Out: Borborygmus
Borborygmus is the technical term for the gurgling and rumbling noise made when liquid and gas move in the intestines.
Foods That Can Cause Gas and Other Symptoms
Many foods and ingredients contain indigestible carbohydrates and fibers that your gut bacteria like—sometimes too much. How they are tolerated is very individual: Some people handle these foods just fine and others less so.
Foods to Watch Out for If You’re Experiencing IBS-Like Symptoms
• Lots of vegetables are included in this category—bad news if you are trying to focus on a vegetable-rich diet—including beans, mushrooms, cabbage, onions, garlic, peas, peppers, radishes, cauliflower, corn, turnips, rutabagas, cucumbers, leeks, and broccoli.
• Check labels for ingredients that may also be problematic, such as polydextrose, fructooligosaccharides, and sorbitol.
• There is also something called resistant starch, which has been shown to cause gas and GI symptoms. Resistant starch is found in hydrolyzed starch, modified food starch, corn starch partially milled or whole grains, seeds, legumes, unripe bananas, potatoes, corn flakes, Hi-maize, Novelose 330, and Crystalean (Nugent, 2005). It can be formed after cooking and cooling foods, so the way a food is prepared can affect how well it is digested.
Avoiding Fructose and Lactose
Lactose intolerance and fructose intolerance can look a lot like IBS symptoms. Diarrhea, whether it’s part of IBS or not, can be caused by foods not being absorbed. Similar to the way milk causes diarrhea and gas in people with lactose intolerance (who don’t digest and absorb the milk sugar lactose), the fruit sugar fructose can cause diarrhea, too. Fructose may be fine when consumed as a part of a whole fruit, but in large amounts in apple juice, pear juice, or high-fructose corn syrup (e.g., in soda), the digestive system is overwhelmed and can’t absorb it all. Some people, especially kids, respond to apple juice with diarrhea because of this high fructose content (Moukarzel, Lesicka, & Ament, 2002).
Simply avoiding fructose, lactose, or both may have dramatic effects. Lactose is found in dairy products, but levels are very low in butter and cream, whey powder, and many aged cheeses. What needs to be avoided is fresh cheeses, ice cream, milk, yogurt, half and half, and powdered milk. (Of course, if you handle dairy products and fruit juices okay, you don’t need to avoid them.)
The FODMAP Diet
FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. Bacteria may use these compounds, resulting in the production of gas. FODMAPs include fibers that our digestive tract does not normally digest, such as inulin, and sugars that many people are able to digest and absorb, such as lactose. The FODMAP diet eliminates inulin, lactose, and fructose, along with most of the problematic foods discussed elsewhere in this article. Clinical studies have shown that for many people, eliminating these foods from their diet will help with symptoms of IBS; it may take one to four weeks to feel the effect. A low-FODMAP diet has also been shown to resolve pain, bloating, and diarrhea in children and adolescents; one study identified lactose and fructans as the most common culprits of these symptoms (Brown, Whelan, Gearry, & Day, 2019).
FODMAPs and the Foods They’re Found In
• Fructans—comprising fructooligosaccharides and inulin—are found in rye, wheat, and vegetables, including onions, garlic, artichokes, asparagus, Brussels sprouts, broccoli, and beets.
• Galactooligosaccharides are found in legumes, including lentils, chickpeas, baked beans, and soybeans.
• Polyols include sorbitol, xylitol, maltitol, and mannitol, which are used in sugar-free, low-sugar, and low-calorie items, such as gums, mints, and cough medicines. These foods tend to be low in calories because we don’t use sorbitol, xylitol, or mannitol, so these polyols are left available to our intestinal bacteria. Polyols are also found in low amounts in some fruits and vegetables.
• Fructose is found in high-fructose corn syrup, honey, agave nectar, and fruit—in particular, fruit juices, apples, pears, cherries, peaches, watermelon, and mango.
• Lactose is found in dairy products, including milk, cottage cheese, yogurt, ice cream, pudding, cream cheese, and all soft cheeses.
Our Q&A with Brigid Titgemeier, RDN, provides information on implementing a low-FODMAP diet for GI symptoms. The International Foundation for GI Disorders and Harvard Medical School have additional information on how to implement this diet. If completely eliminating FODMAPs is helpful, then reintroducing them one at a time can be used to determine the subset of FODMAPs that needs to be avoided. Working with a dietitian is definitely recommended for this (Whelan, Martin, Staudacher, & Lomer, 2018; Lacy et al., 2016).
Wheat and Gluten
There is some evidence, albeit controversial, that a gluten-free diet can improve symptoms of IBS in people without celiac disease (De Giorgio, Volta, & Gibson, 2016). Perhaps some of the confusion is due to the fact that a gluten-free diet cuts out a lot more than just gluten. Wheat contains other possible irritants, including fructans, which are fermentable FODMAPs.
People can be intolerant of gluten or wheat without having celiac disease—it’s called nonceliac gluten sensitivity (NCGS) or nonceliac wheat sensitivity (NCWS). Symptoms of NCGS and NCWS overlap with IBS, and IBS symptoms may be triggered by wheat or gluten (Catassi et al., 2017). The bottom line: Listen to your body, and if it reacts poorly to wheat, believe it.
Antibody Tests to Identify Food Intolerances
It’s not easy to identify and eliminate problem foods through dietary changes. If a simple blood test could identify foods to avoid, it would be welcome. Researchers have proposed that the presence in the blood of antibodies to foods may indicate an intolerance to these foods. In particular, the levels of IgG antibodies in blood samples have been reported to be useful in designing diets for people with IBS. In a randomized controlled trial, people with IBS were tested for the amounts of blood IgG antibodies to foods. Individualized diets were designed to exclude foods targeted by that person’s antibodies. Antibodies to milk products and wheat were common, and these foods were excluded for many participants. After three months, people on the personalized diets reported fewer symptoms of IBS than people in the control group who were prescribed sham diets. People who adhered to their personalized diets reported a 26 percent improvement in symptoms. It’s been suggested that equivalent benefits would be seen with any diet that excluded dairy and wheat. The value of IgG testing is not accepted by mainstream medicine, and further research is needed to determine whether or not it is worthwhile (Atkinson et al., 2004; Hunter, 2005).
Nutrients and Supplements for IBS
Multivitamin supplements are useful to support overall health in diarrheal-type IBS, when nutrients may not be fully absorbed. Certain probiotic supplements have been demonstrated to be helpful for symptom relief, although results are still considered preliminary.
Vitamin and Mineral Supplements
Diarrhea results in poor absorption of nutrients, which means that it is a good idea to eat a nutrient-rich diet and to take vitamin and mineral supplements. If fat is not absorbed, this causes a special problem. Fat forms complexes with calcium, magnesium, and zinc, leading to deficiencies of these minerals when diarrhea is chronic. The fat-soluble vitamins A, E, and K are also lost along with the fat, so a good selection of supplements will contain at least 100 percent of the daily values for these vitamins as well as minerals (Cooper & Heird, 2006; Rude & Shils, 2006; Semba, 2006).
Are Magnesium Supplements Causing Diarrhea?
Beware: Too much magnesium, especially magnesium oxide, can cause diarrhea, and some people are very sensitive to this effect. If diarrhea is a concern, reduce the dose of any magnesium supplement and choose a product with magnesium citrate or malate—product labels will state the form of magnesium. If constipation is a concern, magnesium may be helpful; Phillips’ Milk of Magnesia contains magnesium hydroxide, which is quite laxative.
An extensive review of probiotic supplements in IBS concluded that disturbances in the gut microbiota can play a role in IBS, but it’s not yet clear just how helpful probiotics can be. Here’s the problem: Results from more than fifty trials have been published, but the different studies have used many types of probiotics and have reported both positive and negative results. Additional research is needed to verify the efficacy of the products that seem the best so far (Ford, Harris, Lacy, Quigley, & Moayyedi, 2018).
Probiotics are bacteria, and bacteria are not very stable unless they are kept cold and dry. Some products claim to be shelf-stable, but a hot spell or a little too long in the cupboard, especially in a humid bathroom, could easily kill some of the microbes. Some products state the number of live probiotic bacteria at the time of manufacture, but they don’t guarantee a number through the expiration date. Look for products that guarantee the desired number of live bacteria throughout the product’s shelf life. Benefits for symptoms of IBS have been reported in several studies using 10 billion live probiotic bacteria, but further research is needed to determine optimal numbers and strains.
What Probiotic Strains Are Worth Trying?
Promising results in IBS have been reported with several products containing multiple strains of probiotics:
• One combination that reported significant benefits in two trials comprised Bifidobacterium longum, B. bifidum, B. lactis, Lactobacillus acidophilus, L. rhamnosus, and Streptococcus thermophilus (Lacclean Gold).
• A second combination with promising results comprised B. longum, B. infantis, B. breve, L. acidophilus, L. casei, L. bulgaricus, L. plantarum, and Streptococcus salivarius subspecies thermophilus (Visbiome, formerly called VSL#3).
• A seven-strain combination of L. acidophilus, L. plantarum, L. rhamnosus, B. breve, B. lactis, B. longum, and S. thermophilus containing 10 billion total bacteria provided significant relief from IBS symptoms (Ford et al., 2018).
Beneficial effects on symptoms of IBS have also been reported for a number of individual probiotic species:
• L. plantarum DSM 9843 (also called 299v) is a unique strain of bacteria that is found naturally in the human gut and fermented foods. It’s resistant to stomach acid and survives and grows in the human intestine. Significant improvements in bloating, pain, and feelings of incomplete bowel movements were reported following daily treatment with 10 billion L. plantarum 299v (Ducrotté, Sawant, & Jayanthi, 2012; Niedzielin, Kordecki, & Birkenfeld, 2001).
• Scores of abdominal pain in IBS were significantly reduced by a daily dose of 10 billion L. gasseri BNR17. This is a specific strain of L. gasseri isolated from human breast milk (Kim, Park, Lee, Park, & Kwon, 2017).
• Yoon et al (2018) reported that four weeks of S. thermophilus MG510 and L. plantarum LRCC5193 at a daily dose of 400 million significantly improved stool consistency in IBS with constipation. Even better, quality of life was self-reported as significantly better as long as four weeks after treatment ended.
• Benefits have also been reported with Escherichia coli DSM17252 (Symbioflor 2) and S. faecium (Paraghurt) (Ford et al., 2018).
• Symptoms of IBS were significantly better in people given 10 billion Bifidobacterium infantis 35624 daily, compared to those given L. salivarius. A measure of inflammation was also improved after treatment with B. infantis (O’Mahony et al., 2005).
Prebiotic Foods for Gut Bacteria
Providing food to encourage the growth of desirable gut bacteria is thought to be beneficial for gut health. However, a 2019 review concluded that existing research doesn’t offer much evidence for benefits of prebiotics in IBS and related conditions. The only positive finding was a little evidence that noninulin-type prebiotics, such as partially hydrolyzed guar gum or galactooligosaccharides, may reduce flatulence. Inulin-type prebiotics actually appeared to worsen flatulence (Wilson, Rossi, Dimidi, & Whelan, 2019).
Recent research has looked at pre- and probiotics combined, referred to as synbiotics. Lee et al. (2018) reported that a synbiotic significantly reduced multiple symptoms of IBS compared to a placebo. Treatment consisted of 20 billion of a combination of six strains of Lactobacillus (L. rhamnosus, L. acidophilus, L. casei, L. bulgaricus, L. plantarum, and L. salivarius) and two strains of Bifidobacterium (B. bifidum, and B. longum) with fructooligosaccharides, slippery elm bark, herb bennet, and inulin powder. (The investigational drug was Ultra-Probiotics-500, supplied by B&A Health Products.)
Lifestyle Changes for IBS
Research suggests that reducing stress, getting sufficient sleep, and exercising can all be helpful for IBS, likely influencing the gut-brain axis to help reduce IBS symptoms and to improve quality of life (NIDDK, 2017a).
Exercise can help food move through the intestine and make bowel movements more frequent. A review of fourteen controlled trials concluded that exercise had likely benefits for quality of life and GI symptoms in people with IBS. Types of exercise used in the studies included yoga, walking and other aerobic physical activity, Tai Chi, mountaineering, and Baduanjin Qigong (Zhou, Zhao, Li, Jia, & Li, 2019).
IBS is associated with sleep disturbances (Lacy et al., 2016). One study asked whether melatonin, a sleep aid, would be beneficial for people with IBS and disturbed sleep. Even though subjects receiving melatonin nightly did not fall asleep more quickly or sleep more hours, they reported significantly less abdominal pain compared to a placebo group. Benefits of melatonin for other types of pain have been reported in some, but not all, clinical trials (Song, Leng, Gwee, Moochhala, & Ho, 2005; Zhu et al., 2017). Additional research is needed before concluding that melatonin is not useful as a sleep aid in IBS.
How to Get Restful Sleep
A lifestyle that promotes restful sleep includes these habits:
• Exercise, to wear you out physically.
• Meditate, to help calm a racing mind. Meditation can help you relax peacefully in the here and now instead of holding anxiety associated with the past or the future.
• Avoid bright lights, especially the blue light of computer and cell phone screens.
• Avoid upsetting news or TV before bedtime.
• Reduce your caffeine consumption. In addition to coffee and energy drinks, caffeine is found in green and black teas. Tea labeled “mint” or “black currant” is likely flavored black tea.
• Reduce your alcohol consumption. Alcohol is relaxing in the short term, but it impairs sleep later in the night (Mayo Clinic, 2019b).
Conventional Treatment Options for IBS
There is no known cure for IBS, but there are medications that can help relieve symptoms, such as pain, diarrhea, and constipation. A gastroenterologist can help sort through the medication possibilities for each particular spectrum of symptoms and help weigh the benefits of prescription medications with the risks of adverse side effects.
Drugs to Treat Constipation-Type IBS
Laxatives with polyethylene glycol (PEG) are available over the counter, and one controlled study showed that PEG helped with constipation but not with pain or bloating (Chapman, Stanghellini, Geraint, & Halphen, 2013). Another study reported that PEG was no more helpful than a placebo (Awad & Camacho, 2010), so it may not work in all situations. (Don’t confuse PEG with ethylene glycol, which is poisonous and used in antifreeze.) Polyethylene glycol is all too familiar to those who have had to drink a gallon of it to clean out the intestine in preparation for a colonoscopy. PEG works by increasing the bulk in the stool. There are also prescription laxatives, such as linaclotide, lubiprostone, plecanatide, and tenapanor; these work by increasing fluid in the stool (Black et al., 2018; Corsetti & Tack, 2013; Crowell, Harris, DiBaise, & Olden, 2007).
Drugs to Treat Diarrheal-Type IBS
Loperamide is an over-the-counter drug commonly used for traveler’s diarrhea that works by decreasing fluid in the stool. It doesn’t treat the infection, just the diarrhea, and may help with pain as well. Note: The FDA has issued a warning about the dangers of using more than the recommended dosage of loperamide. Abnormal heart rhythms that can be fatal have resulted from taking higher-than-recommended doses of loperamide, or taking the drug together with certain medications, including Tagamet (cimetidine), Zantac, and others. Discuss possible interactions of loperamide and other medications with your physician.
If diet and lifestyle changes and nonprescription medications are not sufficient, additional medications are available. Low doses of tricyclic antidepressants and SSRIs may be helpful with symptom relief for some people (Lacy et al., 2016). A new class of prescription antidiarrheal drugs are serotonin (5-HT3) antagonists—we can make too much serotonin in the gut, which can cause diarrhea (Fukui, Xu, & Miwa, 2018). Alosetron is a serotonin antagonist used only in severe cases of IBS with diarrhea (Olden et al., 2018). Another possibility for IBS with diarrhea is eluxadoline, which acts on opioid receptors in the gut (Pimentel, 2018).
How Do the Benefits of These IBS Treatments Compare to the Side Effects?
Brian Lacy, MD, PhD, summarized the safety concerns for diarrheal-type IBS treatments. Treatments with the fewest adverse reactions were probiotics and rifaximin (an antibiotic). Serious side effects were more likely with eluxadoline, alosetron, loperamide, and tricyclic antidepressants (Lacy, 2018). These side effects need to be weighed against benefits in discussion with medical professionals.
Treating Spasms and Pain
You may not think of the intestine as being a muscular organ that moves, but it is—it needs to contract and relax rhythmically to move food along the intestine. In IBS, intestinal muscle spasms may cause pain. Multiple antispasmodic drugs can relax smooth muscle and reduce pain in IBS, but their side effects need to be taken into account (Cash, 2018). Antispasmodics can also be used in children to reduce pain from muscle spasms (NIDDK, 2014). Peppermint oil has been shown to be an effective antispasmodic for IBS pain (see the alternate treatment section).
SIBO and Antibiotic Therapy
Symptoms identical to IBS can be caused by small intestinal bacterial overgrowth. In a healthy gut, bacteria should be primarily in the large intestine, but in SIBO, they are found in the small intestine, where they have access to undigested food. SIBO has been reported in people diagnosed with IBS. It is seen more in women, in older people, with diarrhea-predominant IBS, with bloating and flatulence, and with use of proton pump inhibitors and narcotics. Testing for SIBO is done by measuring hydrogen gas in the breath (after consuming some glucose, preferably), but it is not a perfect test.
Assuming that bacteria in the small intestine could be contributing to symptoms of IBS, multiple clinical trials have assessed antibiotic treatment for IBS. Averaging the results from five clinical trials, the antibiotic rifaximin was shown to reduce symptoms by 16 percent in people with nonconstipated IBS. After antibiotic treatment, however, symptoms commonly recur, and it is not clear that repeated use of antibiotics will be efficacious and without adverse side effects (Ford et al., 2018; U. C. Ghoshal, Shukla, & Ghoshal, 2017).
Alternate Treatment Options for IBS
The National Center for Complementary and Integrative Health, which is part of the National Institutes of Health, has summarized the evidence in support of alternative therapies for IBS. There may be benefits from probiotics, hypnotherapy, and peppermint oil and from either actual or simulated acupuncture. Neither conventional nor alternative therapies for IBS are known to cure the condition—they are used for symptom relief.
Exclusion or Elimination Diet
As discussed in the dietary changes section of this article, excluding particular foods or groups of foods, such as lactose, gluten, or FODMAPs, has helped with symptom relief for some people with IBS. Several types of elimination diets are used to identify foods that cause symptoms in individuals. The International Foundation for Gastrointestinal Disorders recommends cutting out suspected problem foods one at a time for twelve weeks each, and it suggests starting with fiber, chocolate, coffee, and nuts. However, it’s more commonly recommended that multiple suspect foods are eliminated concurrently. Simply cutting out one food at a time may not be helpful, as improvement in symptoms may require avoiding all problem foods simultaneously. These foods must be completely eliminated, and if a small portion of one is inadvertently consumed—for example, whey protein from milk in a smoothie—the process must be started from the beginning. If improvement is seen after two to four weeks on an elimination diet, foods are added back one at a time for three days each to identify the offenders. It’s important to note that symptoms may temporarily worsen for a few days at the start of the new diet (Brostoff & Gamlin, 2000; Joneja, 2012).
Examples of Elimination Diets for IBS
• A simple elimination diet might exclude only the most likely offenders, for example, dairy and gluten.
• A moderate elimination diet might exclude FODMAPs, sugar, and other foods suspected of contributing to symptoms of IBS.
• In an attempt to be sure that all problematic foods are excluded, the most extreme “few foods” diets provide a short list of allowed foods. For example, one diet allows only lamb, rice, and pears (Parker, Naylor, Riordan, & Hunter, 1995).
These diets should be created with the help of a registered dietitian because they can be very difficult and leave people without clear answers if not carried out carefully. In addition, such limited diets can cause nutritional problems of their own. Extensive information on implementing an elimination diet can be found in The Inflammation Spectrum, by Will Cole, DC, and in Food Allergies and Food Intolerances, by Jonathan Brostoff, MD, and Linda Gamlin.
Behavioral and Psychological Support
There is a close relationship between the gut and the brain known as the brain-gut axis, and emotional stress and psychological factors can contribute to symptoms of IBS (Farhadi, Banton, & Keefer, 2018). And as might be expected with a chronic medical condition, depression and anxiety are not uncommon in people with IBS. A variety of therapies take advantage of the gut-brain connection to help reduce IBS symptoms and to improve quality of life. Therapies that may work together with medications to help control pain and discomfort include hypnosis, cognitive behavioral therapy, psychodynamic therapy, and mindfulness-based stress reduction.
Many, but not all, controlled clinical trials have shown that cognitive behavioral therapy improves gastrointestinal symptoms, mental health, and the ability to carry out normal daily activities. Benefits were seen for both individual and group therapy, and a few studies even reported benefits from online therapy.
Hypnosis and psychodynamic therapy have also been evaluated in smaller numbers of controlled trials with, again, some but not all trials reporting benefits for mental health and daily functioning (Laird, Tanner-Smith, Russell, Hollon, & Walker, 2016; Laird, Tanner-Smith, Russell, Hollon, & Walker, 2017).
Mindfulness-based stress reduction is an intensive eight-week program developed by Jon Kabat-Zinn that is used to reduce stress and anxiety. Cultivating mindfulness means becoming aware of one’s thoughts and sensations in the present moment—without judgment and with compassion. Researchers from the University of North Carolina at Chapel Hill demonstrated greater benefits for women with IBS from mindfulness training compared to a social support group that met for the same number of hours. Women receiving mindfulness training reported fewer IBS symptoms for three months after completing this course (Gaylord et al., 2011). Results have been mixed in other research (Kearney et al., 2011; Naliboff et al., 2020).
Depending on your preference, the promising results on these therapies may be worth considering.
Acupuncture for IBS Symptoms
An extensive review concluded that both needle acupuncture and electroacupuncture may be helpful in treating symptoms of IBS (Wu et al., 2019). Electroacupuncture achieves strong stimulation by sending a low level of electrical current through needles, resulting in a tingling sensation. (If the current is turned up too far, your muscles will twitch rather creepily.) However, debate will likely continue as to whether the benefits of acupuncture are greater than those from a placebo treatment referred to as sham acupuncture. One analysis concluded that controlled trials have consistently shown acupuncture to be no more helpful for IBS than a sham treatment (Manheimer et al., 2012). On the other hand, a more recent review concluded that acupuncture is more effective than sham acupuncture for IBS with diarrhea (Zhu, Ma, Ye, & Shu, 2018). Another way to look at this: Either actual or simulated acupuncture may be beneficial in IBS.
Peppermint Oil for Multiple Symptoms of IBS
The NIH’s National Center for Complementary and Integrative Health rates peppermint favorably (National Center for Complementary and Integrative Health, 2016). Multiple clinical studies have demonstrated that peppermint oil in enteric-coated capsules is very helpful for multiple symptoms of IBS in both adults and children (Chumpitazi, Kearns, & Shulman, 2018; Ford et al., 2008). It’s thought to act as an antispasmodic that helps intestinal smooth muscle relax, likely due to the bioactive component menthol (Amato, Liotta, & Mulè, 2014). The anti-inflammatory and potent antimicrobial (antiviral, antibacterial, antifungal) properties of peppermint may also be important. Animal studies have demonstrated that it can even reduce GI pain and anxiety (Chumpitazi et al., 2018).
Triphala to Support a Healthy Gut
Triphala is a combination of three fruits: Terminalia chebula, Terminalia bellirica, and Phyllanthus emblica. A cornerstone of gut health in the Ayurvedic tradition, triphala is believed to have multiple benefits for healing the GI tract that could be helpful for people with IBS. Triphala contains tannins, flavonoids, and other phytochemicals with antioxidant and anti-inflammatory properties. Its antibacterial properties have been shown to make it effective as a plaque-preventing mouthwash (Bajaj & Tandon, 2011). Referred to as a mild laxative, triphala has been shown to be useful for constipation, but it is considered to be balancing and may also be useful for diarrhea (Tarasiuk, Mosińska, & Fichna, 2018).
New and Promising Research on IBS
Plenty of interesting research on IBS is ongoing, both to understand what causes this syndrome and to identify better therapies for symptom relief. This article focuses on clinical research on people with IBS, but there is also a large body of relevant research going on in cultured cells and in animal models.
How Do You Evaluate Research Studies and Identify Promising Results?
The results of clinical studies are described throughout this article, and you may wonder which treatments are worth discussing with your doctor. When a particular benefit is described in only one or two studies, consider it of possible interest and perhaps worth discussing, but definitely not conclusive. Repetition is how the scientific community polices itself and verifies that a particular treatment is of value. When benefits can be reproduced by multiple investigators, they are more likely to be real and meaningful. We’ve tried to focus on review articles and meta-analyses that take all the available results into account; these are more likely to give us a comprehensive evaluation of a particular subject. Of course, there can be flaws in research, and if by chance all of the clinical studies on a particular therapy are flawed—for example with insufficient randomization or lacking a control group—then reviews and meta-analyses based on these studies will be flawed. But in general, it’s a compelling sign when research results can be repeated.
The Placebo Effect and the Healing Power of the Brain
Would taking a sugar pill make you feel better? Most people would say no. But the placebo effect has been observed in countless clinical trials. The group getting the placebo (whose members don’t know whether it’s a sugar pill or the real treatment) improves almost as much as—or sometimes better than—the group getting the experimental treatment. The interpretation is that feeling hopeful is enough to rally the body’s healing abilities.
Would it still be beneficial if you knew that you were getting a placebo though? The amazing answer seems to be yes, or at least it was in one well-controlled clinical study of IBS. People were either given nothing or told that they were being given a placebo. After eleven days, subjects given nothing reported improvements in symptoms, and subjects openly given a placebo pill reported even greater improvements (Kaptchuk et al., 2010). One lesson from this is that seeing improvements over time doesn’t necessarily tell us much about how a specific treatment works.
Another study broke down possible components of the placebo effect in an interesting way. Hope and anticipation of being in a trial (being in the waiting list group) was somewhat helpful—20 percent of people reported adequate relief from IBS symptoms. The relief rate was increased to 40 percent in people getting sham acupuncture (referred to as a “therapeutic ritual”). And 60 percent of people reported adequate relief when the sham was combined with “a patient-practitioner relationship augmented by warmth, attention, and confidence” (Kaptchuk et al., 2008). This study provides more evidence for the importance of our mental state and the power that our brain has over our body’s health.
Fecal Microbiota Transplantation to Normalize Gut Microbiota
There appears to be something going on with the gut microbiota—the complete collection of bacteria and other microorganisms—in IBS. Pity the poor lab mouse, given a fecal transplant from a human with IBS, which then develops loose stools and “anxiety-like behavior.” Since 2015, at least twelve studies reported differences in the microbiota of people with IBS compared to healthy people (Fukui et al., 2018). Researchers in the Netherlands reported that they could distinguish patients with IBS from those with inflammatory bowel diseases by looking at the differences in their gut microbiota (Vila et al., 2018). In other research, intestinal infections with campylobacter, Clostridium difficile, Helicobacter pylori, Mycobacterium avium paratuberculosis, salmonella, shigella, viruses, and parasites have been associated with the development of IBS (Shariati et al., 2018).
Since most probiotic bacteria don’t take up permanent residence in the GI tract, the only way we can correct imbalances is to “transplant” a complete human microbiota via feces. This entails obtaining a fecal sample from a healthy person and transplanting it into the colon of a person with gut issues. Fecal transplants have been used clinically for C. difficile infections and are being researched for much more. A well-controlled clinical study was carried out in Norway to see if fecal transplantation would be an effective treatment for IBS with diarrhea. Three months after the procedures, roughly 40 percent of placebo subjects who received transplants of their own feces reported symptom relief, while roughly 60 percent of those receiving healthy feces reported symptom relief (Johnsen et al., 2018). The high placebo effect is fairly typical, and the additional 20 percent treatment effect is considered significant.
However, a similar trial in Denmark did not report a benefit of fecal transplantation. Instead, three months after treatment, symptom improvement was better in the placebo group than in the transplant group. Whether or not fecal transplantation will be useful in IBS is not clear, and further refinement of the approach may be needed (Halkjaer et al., 2018).
Bacterial Methane Gas Production and Constipation
How many of the world’s woes can we blame on methane gas? The methane gas produced by cows contributes to global warming. And methane is also produced by a microbe in humans called Methanobrevibacter smithii. Methane levels can be measured in your breath, and evidence is accumulating that methane production is higher than normal in people who have constipation-type IBS. Methane appears to slow down intestinal movement, resulting in constipation. In one study, high levels of M. smithii in the feces went along with more methane production, more constipation, and more bloating (U. Ghoshal, Shukla, Srivastava, & Ghoshal, 2016). Some antibiotics can target methane producers and may be helpful for constipation.
It was discovered that lovastatin, a commonly used cholesterol-lowering drug, can prevent bacteria from producing methane, and a proprietary form (SYN-010) has been developed that delivers the drug to where the bacteria reside—mostly in the large intestine but also in the small intestine in some people. It has been reported that this drug reduced methane production in people with IBS, and even better, it increased the frequency of bowel movements (Gottlieb et al., 2016). Unfortunately, a phase 2 trial of SYN-010 was ended early, as the drug did not appear to be helping.
Breast Milk Oligosaccharides
Human breast milk contains more than 200 unique oligosaccharides that are food for desirable gut bacteria. The mother’s body uses significant resources producing these fibers that the baby uses very little of—they are intended to feed bifidobacteria and lactobacilli. There is a lot of research on human milk oligosaccharides (HMOs) and their benefits to infants for immunity and allergies, but researchers have also proposed that HMOs could be used in adults. A product called Holigos IBS Restore was given to adults with IBS, and after only four weeks they reported less diarrhea, constipation, pain, and bloating. This was not a blinded trial—people knew what they were getting—and there was no control group. Holigos IBS Restore is a medical food—meant to be used under a doctor’s supervision—that is available without a prescription (Palsson et al., 2019; Triantis et al., 2018).
However, a double-blind controlled study of a different HMO preparation did not report significant benefits. People with IBS were given ten grams of oligosaccharides similar to those in human milk every day for four weeks. The prevalence of beneficial bifidobacterial in their stool increased significantly. But gastrointestinal symptoms were not improved (Iribarren et al., 2020).
Sequestering Excess Bile Acids for Diarrheal IBS
The liver makes bile acids to help with fat digestion. There is some evidence that too much bile may contribute to IBS with diarrhea while too little may play a role in IBS with constipation. Bile acids have laxative effects, and bile acid levels were reported to be higher than normal in stool from people with diarrheal IBS. In preliminary research, bile acid sequestrants (colesevelam and colestipol) were associated with improved stool passage and stool consistency (Wald, 2018; Lacy, 2018). However, in a small controlled clinical trial, treatment with colesevelam for four weeks did not help with symptoms (Vijayvargiya et al., 2020).
Preliminary Research on Curcumin and Essential Oils
Curcumin, found in turmeric, has anti-inflammatory and antioxidant activities. It’s not clear why it would be useful in IBS, which appears to have a small inflammatory component, yet over 1,000 research articles have been published on a possible connection between curcumin and IBS in the past twenty years. Of those, only a few were controlled trials, and when these were analyzed together, there was no meaningful benefit from curcumin. However, positive preliminary results were reported when curcumin was given together with fennel essential oil or with a blend of peppermint, caraway, and other oils. Hopefully, these results can be replicated with standardized preparations in larger numbers of people (Ng et al., 2018).
Itch Receptors and Pain
Joel Castro, PhD, Stuart Brierly, PhD, and colleagues from multiple universities and medical centers spanning the United States, Qatar, and Australia think that they may have identified specific receptors on specific nerves that could be responsible for causing pain in IBS. The “itch receptors,” known to cause the sensation of itching on the skin, have been implicated in causing pain in the colon in mice. Drugs are available that can activate these receptors—the hope is that drugs can be created that can block the receptors and, thus, block pain (Castro et al., 2019).
Clinical Trials for IBS
Clinical trials are research studies intended to evaluate a medical, surgical, or behavioral intervention. They are done so that researchers can study a particular treatment that may not have a lot of data on its safety or effectiveness yet. If you’re considering signing up for a clinical trial, it’s important to note that if you’re placed in the placebo group, you won’t have access to the treatment being studied.
It’s also good to understand the phase of the clinical trial: Phase 1 is the first time most drugs will be used in humans, so it’s about finding a safe dose. If the drug makes it through the initial trial, it can be used in a larger phase 2 trial to see whether it works well. Then it may be compared to a known effective treatment in a phase 3 trial. If the drug is approved by the FDA, it will go on to a phase 4 trial. Phase 3 and phase 4 trials are the most likely to involve the most effective and safest up-and-coming treatments.
In general, clinical trials may yield valuable information; they may provide benefits for some subjects but have undesirable outcomes for others. Speak with your doctor about any clinical trial you are considering. To find studies that are currently recruiting for IBS, go to clinicaltrials.gov. We’ve also outlined some below.
Lin Chang, MD, at UCLA, is carrying out a small trial to see if the Stress Management and Resilience Training (SMART) program developed by Amit Sood, MD, at the Mayo Clinic, will be helpful in IBS. In other populations, this program has been shown to reduce stress and improve quality of life. It’s a nice approach that focuses on gratitude, compassion, acceptance, forgiveness, and understanding of a higher meaning. Enrollment is complete.
A Cognitive Behavioral Therapy App
A mobile app called Zemedy delivers cognitive behavioral therapy to regulate the gut-brain axis. Linda Nguyen, MD, is leading this study at Stanford University School of Medicine to determine whether use of the app can reduce the severity of IBS symptoms.
Tai Chi Lessons
Tai Chi is a Chinese mind-body practice used to promote relaxation and health. Kyle Staller, MD, at Massachusetts General Hospital, is recruiting people with constipation-type IBS for eight weeks of Tai Chi lessons. The study will measure a variety of IBS symptoms before and after the Tai Chi course.
Will online yoga classes be helpful for people with IBS? Kristen Weaver, PhD, at the University of Maryland, Baltimore, is recruiting people with IBS and abdominal pain to participate in six weeks of private online yoga classes. She is also recruiting people without IBS to act as control subjects. In addition to documenting changes in IBS symptoms, stool samples will be used to evaluate changes in the gut microbiome resulting from the yoga practice.
The Low-FODMAP Diet
Stacey Menees, MD, at the University of Michigan, is recruiting for a randomized double-blind clinical study comparing the low-FODMAP diet (plus the laxative PEG) to a sham diet (plus PEG) in people with IBS with constipation. It might seem difficult in this age of information to imagine that people would not figure out whether they are on the actual or sham low- FODMAP diet, but they will make an attempt by imposing comparable restrictions and modifications. This is an early phase 1 trial, meaning this protocol hasn’t been vetted for safety, but the diet and laxative are not new treatments.
And Anthony Lembo, MD, at the Beth Israel Deaconess Medical Center is leading a study to determine whether a low-FODMAP diet will improve measures of leaky gut. This study is currently recruiting people with diarrheal-type IBS in Boston and at the University of Michigan in Ann Arbor.
Antibiotic Treatment for SIBO
Bacterial overgrowth in the small intestine (SIBO) may contribute to IBS. The goal of a clinical study at the University of Michigan led by William Chey, MD, is to better predict who will benefit from antibiotic treatment to kill the bacteria. SIBO will be assessed in people with diarrheal IBS using home-based kits that measure hydrogen gas in the breath. They will then be given the antibiotic rifaximin for two weeks and surveyed about any changes in pain, stool consistency, and other symptoms. The hope is that the results of the breath tests, indicating the extent of SIBO, will predict who will benefit the most from rifaximin.
Electrical Stimulation of the Ear
Electrical stimulation of a specific region of the ear can affect nerve pathways in the brain responsible for feeling pain. Percutaneous electrical nerve field stimulation uses a low level of electrical current applied through needles. In a double-blind clinical trial, adolescents with abdominal pain were treated with PENFS or sham treatment to the ear for four weeks. Those treated with PENFS reported a significant reduction in abdominal pain by three weeks of treatment, with benefits lasting nine weeks (Kovacic et al., 2017). Lin Chang, MD, of the University of California, Los Angeles, is recruiting adults with IBS for a double-blind study to see if a similar treatment can reduce pain and other symptoms.
Curcumin Supplementation for Children
Manu Sood, MD, at the Medical College of Wisconsin, has completed recruitment of children with IBS for a quadruple-blinded study to see how supplementation with curcumin—the active ingredient in turmeric—affects the gut microbiota. After subjects take curcumin or a placebo for eight weeks, both their GI symptoms and their gut microbiota will be evaluated.
The Mayo Clinic website is an excellent resource for more info on IBS.
The most comprehensive resource for IBS is the National Institute of Diabetes and Digestive and Kidney Diseases website, where you can find in-depth information about IBS in children.
Also see goop’s Q&A on understanding and treating IBS with Eric Esrailian, MD, the chief of the Vatche and Tamar Manoukian Division of Digestive Diseases and the director of the Melvin and Bren Simon Digestive Diseases Center at the David Geffen School of Medicine at UCLA.
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