What can I eat for SIBO prep?: A Guide to the Pre-Test Diet

October 7, 2025 •

4 min read

According to SIBO research, improper dietary preparation is a leading cause of inaccurate Small Intestinal Bacterial Overgrowth (SIBO) test results, which can lead to misdiagnosis or mistreatment. Understanding what can I eat for SIBO prep? is the first step toward getting a reliable diagnosis from your breath test.

Quick Summary

Following a restrictive, low-fermentation diet before a SIBO breath test is critical for accuracy. This guide details acceptable foods like plain white rice, specific proteins, and certain fats, while outlining foods and substances to strictly avoid, along with important medication instructions.

Key Points

Low-Fermentation Diet: For 12-24 hours before the test, eat only low-fiber, low-fermentation foods like plain white rice, plain meats, and eggs.
Strict Avoidance: All fruits, vegetables, whole grains, nuts, seeds, and most dairy must be avoided to prevent fermentation that could skew results.
Limited Beverages: The only acceptable drinks are plain water and weak black coffee or tea, with no sweeteners or milk.
Final Fasting Period: A 12-hour overnight fast, allowing only plain water, is mandatory before starting the breath test.
Medication and Supplement Management: Certain medications and supplements, including antibiotics and probiotics, must be discontinued several days or weeks before testing.
Read All Labels: Pay attention to ingredient lists, especially if you are vegetarian or vegan, to avoid hidden fermentable starches and thickeners.
No Smoking or Exercise: Avoid smoking, vaping, or vigorous exercise for at least one hour before and during the test.

The Goal of the SIBO Prep Diet

The primary objective of the SIBO preparation diet is to minimize food fermentation in the small intestine before a breath test. By restricting fermentable carbohydrates and fibers for 12 to 24 hours, you effectively "starve" the gut bacteria, which helps to establish a clear baseline reading for the test. Without this strict adherence, residual gas from previous meals can distort your results, leading to a potentially inaccurate diagnosis. Following the diet precisely helps ensure the hydrogen and methane gases measured during the test are a true reflection of the bacterial activity in your small intestine.

What to Eat for SIBO Prep

For the 12-24 hours prior to your breath test, your diet must consist exclusively of plain, low-fiber foods. The specifics can vary slightly based on your doctor’s recommendations and whether you have slow motility, but a standard list includes:

Proteins: Any meat, poultry, fish, or seafood that is not cured or brined. Baked or broiled chicken, turkey, white fish, or eggs (cooked any style) are excellent choices. Tofu can be used for vegetarian or vegan diets.
Carbohydrates: The only acceptable grain is plain, steamed white rice (Jasmine or Basmati). Plain white bread or simple, plain crackers without seeds or added sugar are also often permitted.
Fats and Oils: Small amounts of coconut oil, olive oil, butter, or lard are acceptable for cooking.
Broth: Clear meat broth made from only meat and water is allowed. It is crucial to avoid bone broth, which can contain polysaccharides that feed bacteria.
Seasonings: Plain salt and pepper are the only spices permitted.
Beverages: Drink only plain water, or weak black coffee or black tea without any sweeteners, cream, or milk.

Sample Meal Plan for SIBO Prep

Here is a simple example of a 24-hour menu based on the low-fermentation guidelines:

Breakfast: Two hard-boiled eggs with salt and pepper.
Lunch: A serving of plain, baked chicken breast with a side of steamed white rice cooked in water.
Dinner: Broiled white fish with a small amount of olive oil, served with plain steamed white rice.
Snacks: Additional eggs or clear meat broth.
Throughout the Day: Drink plenty of plain water and unsweetened black coffee or tea, if desired.

What to Avoid: Prohibited Items Before Your SIBO Test

Sticking to the allowed foods is just as important as knowing what to eliminate. Foods high in fermentable carbohydrates and fiber must be avoided completely.

All Fruits and Vegetables: This includes juices, fresh, dried, and canned versions of fruits and vegetables.
All Whole Grains: Avoid brown rice, oats, whole wheat bread, bran, and pasta.
Legumes, Nuts, and Seeds: All types are prohibited.
Dairy Products: Exclude all milk, cheese, yogurt, and ice cream. Eggs are the exception.
Sugars and Sweeteners: No added sugar, corn syrup, artificial sweeteners, honey, or juices.
Fermented Foods: Probiotics, kombucha, sauerkraut, and yogurt must be avoided.
Certain Meats: Stay away from cured meats, deli meats, sausage, or any pre-prepared meats with added sugars or spices.
Herbs and Spices: Only salt and pepper are allowed. All other herbs and spices are prohibited.
Alcohol: Avoid all alcoholic beverages.

Comparison of SIBO Prep Foods


Food Category	Permitted during SIBO Prep	Forbidden during SIBO Prep
Protein	Baked/broiled chicken, turkey, fish, eggs, tofu	Cured meats, sausage, deli meats
Carbohydrates	Plain steamed white rice, white bread/crackers	Brown rice, whole grains, pasta, potatoes
Fats	Coconut/olive oil, butter, lard	No restrictions on healthy fats
Beverages	Plain water, weak black coffee/tea	Sugary drinks, alcohol, juices, herbal/green tea
Seasonings	Salt, pepper	All other herbs, spices, garlic, onion
Broth	Clear meat broth (no bone/veggies)	Bone broth, vegetable broth, bouillon
Other	-	Fruits, vegetables, legumes, nuts, seeds, dairy

The Final Fasting Period Before the Test

The preparatory diet is followed by a crucial 12-hour fasting period, typically overnight. During this fast, nothing is permitted except plain water. No food, no beverages (including coffee and tea), and no gum or mints. It is also recommended to avoid vigorous exercise and smoking for at least an hour before and during the test, as these can affect gas readings.

Important Medication and Supplement Timing

In addition to the dietary restrictions, you must also stop certain medications and supplements to avoid influencing the test results.

Antibiotics/Antimicrobials: Must be stopped for 2-4 weeks prior.
Probiotics: Discontinue for 1 week prior to the test.
Laxatives/Fiber Supplements: Stop at least 1 week prior.
Digestive Enzymes: Stop 1-2 days before.
Other Essential Medications: Any non-essential medications should be discussed with your doctor to determine if they need to be paused.

Conclusion: Following the SIBO Prep is Key

Successfully adhering to the SIBO prep diet is a non-negotiable step toward obtaining accurate and interpretable breath test results. The restrictive period ensures that the test measures gas production from the specific sugar solution rather than from residual fermentable carbohydrates in your system. By following the low-fiber diet, avoiding certain medications, and completing the final fasting period, you maximize your chances of a clear and conclusive diagnosis. Always consult with your healthcare provider or testing lab for the most specific and up-to-date instructions for your individual test.

Center for SIBO Testing: SIBO Test Preparation

Frequently Asked Questions

No, you must avoid brown rice, pasta, and all other whole-grain products, as their high fiber content will feed the gut bacteria and interfere with test accuracy.

No, all vegetables and fruits, including juices, are strictly prohibited because they are high in fermentable carbohydrates and fibers.

Yes. Vegetarians can rely on eggs and allowed grains, while vegans can use tofu and ensure any processed foods like white bread do not contain hidden dairy or other prohibited ingredients. Some practitioners may recommend a longer fast instead of the prep diet for vegans.

If you accidentally consume a prohibited item, you should inform your doctor. It's often necessary to postpone the test and restart the dietary preparation to ensure accurate results.

You can have weak, black coffee or tea (without milk or sweeteners) up to the start of the 12-hour overnight fast. During the fast and the test itself, only plain water is allowed.

A minimum of 12 hours of fasting is required immediately before the test. This period typically occurs overnight.

Non-essential medications and supplements, including probiotics and laxatives, must be stopped for a specific period before the test. Always consult your prescribing physician about which medications are safe to continue.