What Is IBS? Symptoms, Causes, Treatment, Diet for Irritable Bowel Syndrome

Our gut health can vary from week-to-week depending on our diet and lifestyle, but if you commonly experience abdominal pain and inconsistent bowel movements—especially for an extended period of time—it may be more than the effect of having a few extra slices of pizza during family movie night.

Irritable bowel syndrome (IBS) affects between 25 and 45 million Americans—the majority being female—and while there isn’t a cure, it can be managed. What do we know about what causes IBS and what treatment plan can you expect when seeing a doctor? Here is your guide to IBS and the newest treatment guidelines clinicians follow. 

What is IBS?

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) explains that IBS is actually a group of co-occurring digestive symptoms, all of which are present without signs of damage or disease in the digestive tract. Because symptoms can vary from person-to-person, it is a common misconception that IBS is a “catch-all” for undiagnosable gastrointestinal issues.

Dr. William Chey, MD, AGAF, FACG, FACP, a gastroenterologist, professor and director of the GI Physiology Laboratory at Michigan Medicine, admits that isn’t a completely unheard of conclusion, but it is a myth he is working to change. 

“If you think about 40-50 years ago, there were many diseases which we did not fully understand; whether you’re thinking about celiac disease or microscopic colitis or irritable bowel disease (IBD), we really didn’t understand these conditions,” admits Dr. Chey. “It is then that it will continue to be useful to have a syndrome defined by the presence of symptoms under which we can umbrella patients with these particular symptoms, so that providers and patients can have a construct with which to approach the diagnosis and treatment.”

Related: What You Don’t Know About Your Digestive System

Dr. Chey adds that while there is no test that can rule in IBS, there are additional tests—in addition to the presence of abdominal pain that alters bowel habits—that can rule out other diagnoses that could cause the same symptoms. For example, IBD, while similar in name, is different in that it includes “active inflammation that leads to structural damage in the gastrointestinal tract,” which can be seen during those additional tests mentioned. 

While there is no test that can directly diagnose IBS, research is providing more and more understanding to the syndrome each year. In fact, in the beginning of 2021, the American College of Gastroenterology (ACG) issued its first Clinical Guideline on Irritable Bowel Syndrome, published in The American Journal of Gastroenterology (guidelines of which Dr. Chey was a co-author).

What causes IBS?

The NIDDK admits that there is no definitive conclusion as to what causes IBS. Research is promising, however: Michigan State University published research in Cellular and Molecular Gastroenterology and Hepatology in 2018 that identified cells—called enteric glia—that communicate with sensory neurons, causing early bouts of intestinal inflammation that can lead to IBS. Genetics can also play a role, as the NIDDK notes that if you have a family member with IBS, your chances of having IBS increase.

All this to say: Our understanding of IBS is evolving, as Dr. Chey confirmed. For now, however, precise causes are unknown, even though somewhere between 7 and 21 percent of people have IBS, explains Jessica Bippen, RD, owner of Nourished by Nutrition. “The description is pretty vague because symptoms vary in severity and duration from person to person,” Bippen adds.

IBS symptoms

While the cause is unknown, the symptoms—though they can vary—are not. According to the NIDDK, symptoms of IBS include: 

  • Abdominal pain
  • Changes in bowel movements (diarrhea, constipation or both),
  • Bloating
  • Feelings of unfinished bowel movements
  • Whitish mucus in stools.

The most common of all of these symptoms are pain in the abdomen and changed bowel movements. Again, these come with no signs of inflammation in the gastrointestinal tract.

Related: What Causes Constipation?

“It’s not uncommon for people with IBS to have episodes of both constipation and diarrhea,” notes Bippen. “For individuals who suffer from frequent bouts of diarrhea, dehydration is common.”

IBS symptoms can be caused by lifestyle triggers, as well, and food is an overwhelming example. Bippen points to research out of Norway that found 70 percent of people with IBS experience symptoms related specifically to food. “Some lifestyle triggers include emotional or mental stress, certain medications, gastrointestinal infection, an altered gut microbiome and hormonal changes,” Bippen adds.

IBS treatment

It is important to note there is no cure for IBS. Instead, treating IBS involves managing symptoms. The most common treatment plan for IBS is medication and what you are prescribed depends on your symptoms (some address IBS with diarrhea and others IBS with constipation). However, Dr. Chey notes that it is becoming increasingly clear from research and literature that medication should be just one part of managing IBS and the new ACG guidelines issued reflect this evolution of treatment. 

Because of this, IBS should be treated holistically, addressing the additional lifestyle factors that can be triggered is also important. Dr. Chey adds that modifications to diet and behavioral interventions such as cognitive behavioral therapy (CBT) are effective forms of treatment, with evolving research on more modalities. 

Related: 10 Easy Ways to Restore Your Gut Health

“[Along with] diet, behavior and medications, the fourth [method] will likely be natural treatments and complementary alternative treatments,” specifies Dr. Chey. “They are not as evidence-based right now, but a lot of groups are focusing on that more and more.”

Some alternative treatments, however, do have proven efficacy, including peppermint oil—”an evidence-based treatment for abdominal pain and bloating for IBS patients,” explains Dr. Chey—glutamine and acupuncture

IBS diet

The ACG guidelines for IBS treatment address suggested dietary modifications, credible because of the high percentage of patients who have symptoms triggered or worsened by certain foods. “Everyone in the gastrointestinal and primary care community accepts diet plays a really big role,” confirms Dr. Chey. 

Bippen indicates the most widely recommended dietary change includes implementing what is known as a low-FODMAP (fermentable oligo-, di-, monosaccharides and polyols) diet. As part of beginning a low-FODMAP diet, individuals eliminate certain groupings of food to then slowly reintroduce them, thus determining how much of specific foods that are part of specific FODMAP categories can be tolerated. 

“Research shows that up to 86 percent of people with IBS saw improvements in their symptoms on a low-FODMAP diet, so this can be a very effective approach to managing symptoms,” notes Bippen. “It’s best to work with a dietitian throughout this protocol to ensure you are getting enough of the necessary nutrients, since it’s quite restrictive and takes a few months to go through the process correctly.”

Related: How to Do an Elimination Diet

Bippen also recommends monitoring water and fiber intake, noting that both can help with constipation and diarrhea. 

“Slowly adding in fiber while drinking enough water can help individuals who suffer from constipation (IBS-C),” she adds. “This may help stool frequency and ease constipation.

If you have diarrhea (IBS-D), you’ll need to find your sweet spot with fiber intake, as too much fiber can make your symptoms worse. Also, be sure to drink at least eight glasses or half of your body weight in ounces of water per day because diarrhea can cause dehydration.”

Next up, read this list of 200 low-FODMAP foods to reduce IBS flare-ups.