The Small Intestinal Bacterial Overgrowth (SIBO) prep diet is a temporary, highly restrictive eating plan followed for 12 to 24 hours before a breath test. Its sole purpose is not long-term symptom management but rather to 'starve' the bacteria in your gut so that test results are not skewed by recent meals. For the most accurate results, it is imperative to follow your healthcare provider's specific instructions precisely. Failing to adhere to the diet can lead to false negative results.
What is the SIBO Prep Diet?
Often referred to as the 'white diet,' the SIBO prep diet eliminates all fermentable carbohydrates, fiber, and added sugars for a short period before the breath test. This significantly reduces the food source for intestinal bacteria. The breath test then uses a controlled sugar solution (lactulose or glucose) to specifically measure the gas produced by any bacterial overgrowth present, without interference from regular food. The following food lists are standard guidelines, but you should always confirm details with your doctor.
Approved Foods for the SIBO Prep Diet
Protein Sources
- Plain, unseasoned meat and poultry: Skinless chicken or turkey, baked or grilled.
- Fish and seafood: Plain fish, not cured or brined. Sashimi is acceptable without sauce.
- Eggs: Plain eggs.
Carbohydrates and Starches
- Plain, steamed white rice: Specifically white rice, as other grains like brown rice and quinoa contain higher fiber that can interfere with the test.
- Plain white bread or crackers: Without seeds, whole grains, or added sugars.
Fats and Oils
- Healthy oils: Coconut oil, olive oil, or vegetable oil.
- Butter or lard.
Beverages
- Plain water: The only beverage allowed during the 12-hour fasting period before the test.
- Weak black coffee or tea: Unsweetened and without cream. Green or herbal teas are not allowed.
Seasoning
- Salt and pepper: These are the only acceptable seasonings. Avoid all other herbs, spices, and complex seasonings.
Foods to Strictly Avoid Before a SIBO Test
- Fruits and vegetables: All fresh, dried, or cooked fruits and vegetables are strictly forbidden, as they contain fermentable carbohydrates and fiber. This includes juices.
- Legumes, nuts, and seeds: All beans, lentils, nuts, and seeds are high in fiber and should be avoided.
- Whole grains: Including brown rice, oats, bran, and products made from them.
- Dairy products: Milk, yogurt, ice cream, and cheese.
- Sugars and sweeteners: Refined sugar, honey, high-fructose corn syrup, agave, and artificial sweeteners.
- Fermented foods: Kombucha, sauerkraut, and flavored yogurts.
- Alcohol and sugary drinks: Including soda and fruit juices.
- Bone broth: Unlike clear meat broth, bone broth can contain substances that may interfere with testing.
- Smoking: No smoking or vaping for at least one hour before and during the test.
Sample One-Day Meal Plan (Prep Diet)
- Breakfast: Two plain, scrambled eggs cooked with a little olive oil, seasoned with salt and pepper.
- Lunch: A baked, skinless chicken breast with a side of plain white rice, seasoned with salt.
- Dinner: A piece of plain, broiled fish.
- Throughout the day: Drink plenty of plain water, and a cup of weak black coffee or tea if needed. Avoid snacking between meals to aid gut motility.
SIBO Prep vs. SIBO Management Diets
| Feature | SIBO Prep Diet | SIBO Management Diets (e.g., Low FODMAP) |
|---|---|---|
| Purpose | To 'starve' bacteria for a short time to ensure accurate breath test results. | To manage chronic symptoms by identifying and eliminating individual food triggers over a longer period. |
| Duration | Very short (12-24 hours) before the test. | Longer-term (weeks to months) elimination and reintroduction phases. |
| Restrictiveness | Extremely restrictive, limited to a few specific plain foods. | Restricts specific fermentable carbohydrates (FODMAPs), but often allows for more food variety than the prep diet. |
| Food Variety | Very low variety, focuses on protein, white rice, fats, water, and salt/pepper. | Much higher variety, including many fruits, vegetables, grains, and nuts, in low-FODMAP quantities. |
| Goal | To obtain an accurate diagnostic test result. | To reduce symptoms and improve quality of life. |
Important Considerations Beyond Diet
- Medications and supplements: Discuss with your doctor which non-essential medications, supplements, probiotics, and digestive enzymes to stop taking prior to the test. Probiotics and antibiotics must often be stopped weeks in advance.
- Fasting period: After the 12-24 hour prep diet, a strict 12-hour fast is required before the test, during which only plain water is permitted.
- Activity: On the day of the test, avoid vigorous exercise and stress. You should also avoid sleeping during the test.
- Oral hygiene: Do not use mouthwash before the test.
By following this precise protocol, you can set the stage for an accurate diagnosis. The diet is temporary, but its importance in the diagnostic process is paramount. After the test is complete, your doctor can guide you on the next steps, which may involve a long-term management diet or treatment plan. For more information on the breath testing process, the Cleveland Clinic offers useful resources.
Conclusion
Understanding what you can eat on the prep diet for SIBO is the first step toward an accurate diagnosis. This temporary, restrictive regimen is designed to clear the digestive tract of interfering foods, allowing the breath test to accurately measure bacterial overgrowth. While the diet is challenging due to its limited scope, strict adherence to the protocol and your doctor’s instructions is non-negotiable for obtaining reliable results. Following this period, a long-term SIBO management diet, such as a low-FODMAP plan, may be recommended to help control symptoms effectively.
