What Is SIBO? A Dietitian's Guide to Diagnosis, Treatment, and Diet
Living with SIBO (Small Intestinal Bacterial Overgrowth) can be an overwhelming and frustrating experience. The constant discomfort, misdiagnoses, and ineffective treatments often leave people feeling stuck and hopeless. But with the right guidance, relief is possible.
Sarah Mirkin, an LA-based registered dietitian, knows this firsthand—not just as a professional but also through her own personal journey. Sarah struggled with digestive issues earlier in her life, eventually discovering she had SIBO. At a time when SIBO was barely understood, she worked closely with Dr. Mark Pimentel, a leading GI specialist, to uncover effective treatments. Through this experience, she not only healed herself but also developed a deep passion for helping others navigate their own gut health challenges.
Sarah shares her expert advice on understanding SIBO, achieving an accurate diagnosis, and finding long-term relief through personalized treatments and sustainable dietary approaches. Whether you're newly diagnosed or have been struggling for years, read on for Sarah's insights.
What is SIBO?
SIBO (Small Intestinal Bacterial Overgrowth) is a digestive condition that shares many symptoms with IBS (Irritable Bowel Syndrome). Symptoms of both conditions include bloating, abdominal pain, and irregular bowel movements.
As the name implies, SIBO occurs when bacteria begin to overgrow in the small intestine. This overgrowth disrupts normal digestion and absorption, leading to symptoms similar to IBS. There are three main types of SIBO: hydrogen-dominant, hydrogen sulfide-dominant, and methane-dominant (also known as Intestinal Methanogen Overgrowth, or IMO).
One of the biggest issues in managing SIBO is misdiagnosis. Sarah points out that many cases of IBS are actually caused by SIBO, yet this connection is frequently missed by healthcare providers. Many doctors are unfamiliar with SIBO and may label patients with IBS without investigating further.
Common recommendations for IBS can actually worsen symptoms in cases of SIBO. Because of that, it's very important to know which one you're dealing with, and to work with a knowledgeable specialist who understands the nuances of these conditions.
Is it SIBO or IBS?
For those wondering if they might have SIBO, Sarah emphasizes the importance of proper testing.
The least invasive method to test for SIBO is a breath test. Sarah recommends the Trio Smart Breath Test, a tool that measures three gases—hydrogen, methane, and hydrogen sulfide. Unlike older tests that measure only two gases and often produce false positives or negatives, the Trio Smart test provides a more accurate picture of what's happening in the gut.
Fun fact: Sarah was one of the first people to ever take a breath test for SIBO, since she worked with Dr. Pimentel at the time it was discovered.
Patients can order the Trio Smart test themselves. But, they'll need a doctor to prescribe the lactulose solution for the most reliable results. Using a prescribed lactulose solution instead of the standard glucose solution provides a more comprehensive view of bacterial overgrowth.
If the test confirms SIBO, Sarah recommends seeking out a GI specialist and a Monash-trained dietitian, as treatment needs to be tailored to the specific type of overgrowth.
Of course, Sarah herself is one such dietitian you can reach out to! She teaches people the low FODMAP diet prior to treatment. That way, they are able to follow a strict low FODMAP diet once they finish the treatment and get immediate relief. She usually also tells clients about the protocol for SIBO, their treatment options, and recommends a highly knowledgeable doctor to work with. Since many doctors aren't knowledgeable about the treatment options, Sarah's guidance is key to getting the best care.
SIBO Treatment Options
Treating SIBO requires a targeted approach based on the type of overgrowth (hydrogen, hydrogen sulfide, or methane-dominant/IMO). Sarah emphasizes that there are several effective treatment options, each tailored to the individual's needs, preferences, and the severity of their condition.
Antibiotic Therapy
Targeted antibiotic therapy is one common and effective treatment for SIBO. In particular, an antibiotic called XIFAXAN (rifaximin) is used. This antibiotic is unique because it works specifically in the small intestine without affecting the rest of the body.
For methane-dominant SIBO (IMO), XIFAXAN is combined with neomycin, a stronger antibiotic, since IMO requires a more aggressive approach.
Treatment typically lasts two weeks.
Herbal Antimicrobials
For those who prefer a natural route, herbal antimicrobials can be an alternative. However, Sarah notes that this method is less targeted and may kill beneficial gut bacteria along with the harmful ones. Herbal treatments also take longer (4-6 weeks) and can cause "die-off" symptoms, such as flu-like discomfort, for several days.
Elemental Diet
The elemental diet is a liquid-only nutrition plan designed to starve the bacteria in the small intestine. The liquid is absorbed directly into the bloodstream, bypassing digestion entirely.
This method typically lasts two weeks and is highly effective, though it can be challenging for patients to follow, since you cannot eat any solid food during the treatment.
The treatment options for SIBO are continually developing. For example, Sarah notes, Dr. Pimentel recently developed a new elemental diet formula that is free of any low calorie sweeteners — optimal for treating SIBO.
Each treatment option has its pros and cons, and a knowledgeable specialist like Sarah can help you choose the best fit for you.
The Importance of Diet for SIBO
Diet also plays a critical role in managing SIBO. The low FODMAP diet is one of the most effective tools for symptom relief. It's an elimination diet that removes fermentable carbohydrates (FODMAPs) that feed bacteria in the gut.
The low FODMAP diet is not meant to be permanent. Instead, it's implemented in three phases: an elimination phase to reduce symptoms, a reintroduction phase to identify personal triggers, and a maintenance phase.
Sarah specializes in helping clients navigate this diet and the reintroduction process, tailoring it to their individual needs and ensuring it's practical and sustainable. She's even written a book, The Beginner's Guide to Low FODMAP, that makes following it easier and more delicious.
Social situations & eating out while on the low FODMAP diet
Eating out can be challenging on a low-FODMAP diet, and people are sometimes embarrassed to ask for all the modifications they need in front of friends.
To help her clients through this, Sarah offers tactical advice. "If someone will be in a situation where they will be embarrassed to make special requests, I always recommend calling the restaurant ahead of time," she says. "Ask questions like, 'What food can I get without garlic or onion?' so you don't have to navigate it in front of your group. You can even ask them to let the waiter know in advance."
For those who feel comfortable, Sarah suggests being upfront with friends or servers. "In Los Angeles, if you tell a restaurant you have an allergy to garlic and onion, they take it very seriously," she notes. "It's a simple way to avoid discomfort without needing to explain your entire diet."
How fast will I notice a difference?
With Sarah's tailored guidance, clients often notice improvements after just 4 days on the low FODMAP diet.
Relief is Possible
With the right diagnosis, treatment plan, and dietary adjustments, you can take control of your symptoms and feel like yourself again. In Sarah's words, "Once people start following the right approach, the changes can be life-changing—even within just a few days."
If you suspect you have SIBO or have been struggling with IBS symptoms that won't improve, it's time to take the next step. Start by seeking out a knowledgeable specialist who understands SIBO and can guide you through proper testing. Then, work with an expert like Sarah to develop a personalized treatment plan.
You don't have to suffer in silence or settle for ineffective solutions. Sarah is living proof that with the right tools and support, you can heal your gut, regain your energy, and enjoy life without constant discomfort.
Sarah Mirkin is a Registered Dietitian Nutritionist and the Founder of Kitchen Coach. She is taking on new clients. To become a client, reach out using her website.