SIBO: What Is It and Do You Have It?

Abdominal pain, gas, bloating, nausea, constipation, diarrhea — these are all symptoms of irritable bowel syndrome (IBS), but they can also be symptoms of a little-known condition called small intestinal bacterial overgrowth (SIBO). While many know about IBS — a condition that affects 25 to 45 million people in the U.S — SIBO may be the under-the-radar culprit behind your stomach issues. So what is SIBO and how do you treat it?

Health Matters spoke with Ryan Warren, a registered dietitian nutritionist at the Jill Roberts Center for Inflammatory Bowel Disease at Weill Cornell Medicine and NewYork-Presbyterian/Weill Cornell Medical Center, to explain this gastrointestinal condition that may be more common than you think.

What is SIBO?
SIBO is an imbalance in the gut when the small intestine experiences an overgrowth of bacteria that usually reside in the large intestine. To put it simply, it’s too much gut bacteria in the wrong location. You can have SIBO without having IBS, and some experts believe SIBO to be the cause of many IBS symptoms. It can be challenging to tell the difference, so a SIBO diagnosis is often established after a definitive work-up, such as a hydrogen breath test.

What are the symptoms of SIBO?
Symptoms range but can include production of gas that can cause increased flatulence, bloating, abdominal cramping/pain, and irregular bowel movements (either diarrhea or constipation). Increased burping can also occur after a meal. Some people may develop symptoms like fatigue, brain fog, headaches, and even skin rashes.

SIBO may interfere with normal digestion and absorption of nutrients — most commonly, vitamin B12, and in some cases, iron — and may be a triggering factor for “leaky gut,” which happens with damage to the intestinal lining over time. This can predispose people toward developing food sensitivities, allergies, and an overactive immune response, which causes inflammation.

Is it life-threatening?
No, SIBO is generally not life-threatening. In very severe cases, malnutrition might be a significant issue warranting serious attention, but most of the time it causes very frustrating, uncomfortable, and sometimes painful symptoms.

What causes SIBO?
There are many potential causes and triggering factors. In some cases, it’s a combination of factors that make certain people more susceptible. One of these is low stomach acid (for example, if you’ve been taking acid-suppressing medications for a long period of time). Normal acid production in the stomach acts as a defense mechanism against bacterial overgrowth. Other abnormalities such as sluggish motility, which is muscles contracting to mix and propel contents in the gastrointestinal (GI) tract, conditions like diverticulosis, and previous abdominal surgery are also risk factors, as is frequent use of antibiotics that interfere with the gut’s balance of healthy bacteria.

Other GI conditions, such as inflammatory bowel disease (IBD) and celiac disease, can make patients more prone to developing SIBO. High stress levels and a long-term poor diet are also linked to predisposition for SIBO due to the effect they have on the gut’s bacteria.

How can it be treated?
The many treatment options range from antibiotics to alternative herbal antimicrobials to dietary treatment options. Talk with your doctor or a registered dietitian about what course of treatment they recommend for your individual case.

What can you do to prevent SIBO?
I usually tell my patients to eat a healthy, varied, whole-foods diet that helps to cultivate a healthy gut microbiota. Avoid processed junk food, unnecessary additives, and excess added sugars. Stress management is also key. In some cases, a probiotic supplement may be helpful for long-term maintenance. Try to steer clear of long-term acid-suppressing therapies unless medically necessary!

There is no diet for “fending off” SIBO, per se, but adjusting the types of carbohydrates (which bacteria love to feed off of) we eat may help minimize symptoms. For example, you could try a low-FODMAP diet. This alone, however, isn’t a sole treatment approach.

More research is needed to understand the complexity of this condition, but progress is being made. What’s most important is to treat patients using an individualized and customized approach.

Ryan Warren, M.S., RDN, CDN, a registered dietitian nutritionist at the Jill Roberts Center for Inflammatory Bowel Disease at Weill Cornell Medicine and NewYork-Presbyterian/Weill Cornell Medical Center, specializes in providing evidence- and practice-based nutrition education and counseling for patients with a variety of complex GI conditions, including Crohn’s disease, ulcerative colitis, IBS, SIBO, diverticulosis, diverticulitis, constipation, diarrhea, and gastroesophageal reflux disease (GERD).