What You Need to Know Before Testing for SIBO

What You Need to Know Before Testing for SIBO

You’re fed up of being asked if you’re pregnant. You’re tired of feeling nauseous, full, and bloated. Your life is dictated by your IBS symptoms.

While we may chalk up the big, bloated stomach that many endo warriors suffer with to what is known as “endo belly,” there could be a lot more to it. In fact, period expert Nicole Jardim recently shared in her book “Fix Your Period” that a shocking 80% of endometriosis patients were found in a study to have small intestine bacterial overgrowth.

Today, I’m exploring how to prepare for a SIBO test to ensure you get the most accurate diagnosis if you suspect that it is the cause of your IBS issues.

Before you take your breath test for SIBO, you must do a preparation diet for one day and an overnight fast. The point of this specialist eating plan ahead of the test is to reduce the level of fermentation in the gut to obtain an accurate diagnosis. We know that SIBO creates fermentation in the small intestine as a result of bacteria accumulating where it shouldn’t be. The gases released during this process cause all the nasty symptoms, and they’re measured during the test.

Fermentation also occurs in the large intestine, where bacteria are supposed to be, so gas occurs there, too. Therefore, if you did a breath test the day after eating a diet full of highly fermentable foods, we couldn’t be sure the gas being recorded in the results is the gas we’re looking for and not just left over from a carb-heavy diet.

As a result, when testing, adopting a low-carb diet the day beforehand is advisable. That diet tends to consist of meat, eggs, white rice, and white bread, a little oil, a little salt, and weak black tea or coffee.

If you had constipation, which is common in people with methane type SIBO, then the prep diet would be required for two days rather than one.

Unfortunately, there’s no cutting corners here! Eating more carbohydrates than the guidance allows impairs the test and makes repeating it necessary.

Considering that, it’s worth hesitating before you dive into a bowl of rice. Nearly every lab I’ve used so far states that it’s OK to eat white rice and white bread. This is because they are simple carbohydrates and break down quickly in the small intestine. In theory, that wouldn’t leave bacteria much time to ferment the food. But this is not the case for everyone.

“Trigger” foods are highly variable in many SIBO patients, and often depend on the amount and type of bacteria you have. Aggravated symptoms are a sign that SIBO bacteria have had a good munch on whatever you’ve eaten.

Additionally, if you have slow gut motility, which is a leading cause of SIBO, then your digestion will be slowed down, resulting in food hanging around much longer in the small intestine, including white bread and white rice.

Given this, it’s wise to only eat white rice or white bread if you know they don’t cause you problems, because if they do, it’s likely they will impair your results, and you’ll have to retest.

But what if you’re vegan or vegetarian? Alternatives exist but come with possible complications.

SIBO expert Dr. Allison Siebecker suggests vegetarians try white rice or white bread, eggs, hard-aged cheese, and perhaps low fermentable vegetables and fruits in tiny amounts.

If you’re vegan, she suggests white rice or white bread, low-Fodmap fruits and veggies, plain, firm tofu, or even a water fast if you’re concerned about carbohydrate levels causing gas production.

She also acknowledges how difficult the prep diet and fast is for diabetics, and suggests small amounts of low-Fodmap fruits and veggies to support blood sugar levels.

Clearly this is a restrictive form of eating, and some can find it triggering if they have a history of disordered eating. If this is the case for you, I recommend working with a SIBO specialist and counselor or another mental health professional that can support you through the process. If you’re not sure where to start, this episode by SIBO coach Rebecca Coomes is insightful.

If you’re still feeling unsure about testing alone without guidance, Siebecker has a patient course online and a list of practitioners on her website. I also list some great resources here.


Note: Endometriosis News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. The opinions expressed in this column are not those of Endometriosis News or its parent company, BioNews Services, and are intended to spark discussion about issues pertaining to endometriosis.