The Story Behind the SIBO Bi-Phasic Diet

Share this post!

An Interview with Dr. Nirala Jacobi, ND (Part 1 of 2)

The trillions of microorganisms that reside in the gut are critical for supporting overall health. Beneficial gut bacteria modulate digestion, immune function, and more. However, the excessive growth of bacteria in the small intestines can lead to serious health problems.

The condition known as small intestinal bacterial overgrowth (SIBO) is becoming increasingly common. SIBO is present in more than half of people who have irritable bowel syndrome (IBS) and as many as 500 million people worldwide.

Effective treatment of SIBO requires care from a qualified healthcare professional. Treatment protocols often include prescriptions for antimicrobials and prokinetic medications. Although diet cannot eradicate SIBO on its own, it can be extremely beneficial as a supportive measure for people with SIBO.

Dr. Nirala Jacobi, ND, is one of the world’s leading experts in SIBO treatment. She is the host of The SIBO Doctor Podcast and the founder of The SIBO Doctor educational website. Dr. Jacobi developed the SIBO Bi-Phasic diet, which has since been utilized by thousands of healthcare practitioners around the globe. 

We had a unique opportunity to talk with Dr. Jacobi about the story behind the SIBO Bi-Phasic Diet and how it can be personalized for each individual. This article is the first of a 2-part interview with Dr. Jacobi.

Sarah Cook: Dr. Jacobi, what was your motivation for developing the SIBO Bi-Phasic Diet?

Nirala Jacobi: When I started out as a clinician, I had a general naturopathic practice in Montana. That was more than 20 years ago, and nobody even knew about SIBO. I first learned about SIBO when I was attending a medical conference and heard a lecture from Allison Siebecker. I was immediately fascinated and made it my mission to learn as much about SIBO as I could.

I had already moved from America to Australia, and around that time I started to educate practitioners about SIBO and eventually  I opened a center for functional digestive disorders, called the Biome Clinic. My practice became entirely focused on helping patients with SIBO and related gut problems.

In working with my SIBO patients and making dietary recommendations, I faced several challenges. Diets can be extremely confusing and variable. Many of my patients needed customized approaches that not only helped with SIBO but also helped with leaky gut or digestive deficits or food intolerances. Then there was the issue of people who were malnourished because of SIBO.

I needed a more structured approach to diet for my patients with SIBO. I needed a formula to follow for consistent results but one that I could also customize for each individual. That’s what led me to develop the SIBO Bi-Phasic Diet.

Cook: What other diets are available that are specific to SIBO?

Jacobi: The fundamental idea when it comes to diets for SIBO is to decrease the availability of fermentable carbohydrates. Fermentable starches serve as a fuel for the gut bacteria and only worsen a problem of bacterial overgrowth.

So, most dietary approaches for SIBO are based on the Low-FODMAP Diet, which restricts fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. I have found with my patients, however, that the Low-FODMAP Diet is not restrictive enough. They would follow it and continue to be quite symptomatic.

The other helpful resource for SIBO-specific diets is Dr. Allison Siebecker’s SIBO Specific Food Guide. When I developed the SIBO Bi-Phasic Diet, I built upon information from the Low-FODMAP Diet, the Specific Carbohydrate Diet (SCD) and Dr. Siebecker’s guide.

Cook: Can the Paleo or ketogenic diets be helpful for SIBO?

Jacobi: The Paleo and ketogenic diets are not specific to SIBO. Paleo diets have too much fermentable fiber. Ketogenic diets are high in fat. Both of these things could be problematic for people with SIBO. One concern about a high-fat ketogenic diet is that many people with SIBO have trouble with bile deconjugation. They cannot very effectively emulsify and absorb fats. Because we have dietary protocols that are specific to SIBO, there really is no compelling reason for a person who knows they have SIBO to follow a Paleo or ketogenic diet.

Cook: Why is your diet called “Bi-Phasic”?

Jacobi: I wanted a method to treat my patients in a sequential manner. It was important to me to have a way to do this with diet so that I didn’t need to send my patients out the door with dozens of supplements. So, I wanted to have a way to reduce and repair (Phase 1) and then to remove and restore (Phase 2).

The idea is that we begin in Phase 1 to reduce fermentable starches and fiber so that we can reduce bacterial fermentation. That means we begin with a very restrictive food plan. At the same time, we begin to repair the digestion with things like bitters or bile support or digestive enzymes.

Then in Phase 2, we actively remove the bacterial overgrowth. This is the phase when we combine the diet with a prescription antibiotic or herbal antimicrobials. At the same time as removing the bacteria, we continue to work to restore digestive health—especially the brush border enzymes and motility.

Cook. How restrictive is Phase 1 of the Bi-Phasic Diet?

Jacobi: There are two parts to Phase 1, beginning with restrictive and moving to semi-restrictive. The restricted diet on Phase 1 is mainly limited to meats and vegetables. All grains, legumes, dairy, and fruits are avoided (except if somebody is following the vegetarian version of the diet, which is based on sprouted grains and legumes). The restricted diet also puts a limit on the exact quantity of certain vegetables that can be consumed per meal. For example, a person can have only one spear of asparagus or one stick of celery or ½ cup of broccoli per meal.

The restricted Phase 1 should be followed for about 1-2 weeks, or until the person begins to see their symptoms improve. Then they move into the semi-restricted Phase 1. Larger quantities of certain vegetables are allowed per meal, and some additional foods are allowed.

I recommend that people continue to follow semi-restricted Phase 1 until their symptoms are 50% to 60% improved. Most people spend a total of about 4-6 weeks in Phase 1 and then move into Phase 2. The nice thing is that it can be self-guided, based on individual improvement.

Cook: What tips do you have for food re-introduction during Phase 2?

Jacobi: Because Phase 1 of the Bi-Phasic Diet eliminates many potentially allergenic foods, Phase 2 can be a useful time to watch for food reactions. Foods like dairy, eggs, and almonds are all allowed during Phase 2 of the diet, but these can be common allergens. Introduce these foods carefully and watch for any reactions.

Phase 2 of the diet is meant to complement other therapies that are recommended by a healthcare practitioner. This is the phase when antimicrobials become important to kill off the bacteria. There’s a good reason that we make the diet less restrictive at this phase.

Dr. Mark Pimental, who is a premier SIBO researcher, actually recommends that patients not follow a restrictive diet when taking antimicrobials. The reason is that he wants the bacteria to flourish during a course of antibiotics so that we can eradicate them. I have found this strategy to backfire. I find that with my own patients, it works best to keep them on Phase 2 of the Bi-Phasic Diet during antimicrobial treatment because it allows for some bacterial fermentation but not enough to aggravate symptoms.

Cook: Is the SIBO Bi-Phasic Diet meant to be followed for life?

Jacobi:  Phase 1 of the diet is typically followed for about 4-6 weeks. Then Phase 2 is followed for another 4-6 weeks. The SIBO Bi-Phasic diet is not a stand-alone treatment and will not eradicate SIBO on its own. It’s meant as a supportive measure to help manage symptoms while people are undergoing more comprehensive protocols for SIBO.

One study found that as many as 44% of people who had been successfully treated for SIBO suffered from relapse. The reasons for relapse are too extensive to go into now, but relapse often happens because the underlying cause is never resolved. Many people choose to follow Phase 2 of the Bi-Phasic Diet as a maintenance strategy while they wait to see if they are going to relapse. 

You can download the complete SIBO Bi-Phasic Diet at Read part 2 of this interview with Dr. Jacobi, where we will discuss ways to modify and supplement the SIBO Bi-Phasic Diet to meet individual needs.

About the Author

Sarah Cook, ND, is an instructor at the Nutrition Therapy Institute. She is also the owner of ND Pen, providing branding, copywriting, and website design services for integrative healthcare practitioners. Connect with Sarah at 

Image:  Image by is free for use by Pexels

Share this post!