The elemental diet is a highly effective yet underutilized tool for treating a variety of gut-related disorders, including small intestinal bacterial overgrowth (SIBO), a gastrointestinal disorder commonly misdiagnosed as irritable bowel syndrome. This article aims to explore the utility of the elemental diet in treating SIBO and offer practical guidance for successfully implementing this dietary approach for those who qualify.
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Understanding SIBO
Small intestinal bacterial overgrowth (SIBO) is a gastrointestinal condition characterized by excessive bacteria in the small intestine. As our understanding of SIBO has evolved, we have been able to distinguish three subsets of SIBO, determined by the gas the overgrown microbes in the intestines produce:
- Hydrogen-Dominant SIBO is caused by bacteria that produce hydrogen gas. Hydrogen-dominant SIBO shares many similarities with diarrhea-predominant irritable bowel syndrome (IBS-D). (16)
- Intestinal Methanogen Overgrowth (IMO) is caused by an overgrowth of a microorganism called archaea in the small or large intestines. IMO shares many similarities with constipation-predominant irritable bowel syndrome (IBS-C).
- Hydrogen Sulfide SIBO is caused by bacteria that produce hydrogen sulfide gas (16).
A relatively low concentration of bacteria grows in the small intestine (especially in comparison to the large intestine, which houses the gut microbiome) in a healthy digestive tract. Various factors can allow these microorganisms to overgrow, including:
- Digestive enzyme deficiencies
- Poor intestinal motility
- Anatomical anomalies within the intestines
- Immune deficiencies
Patients who have SIBO often complain of IBS-like digestive symptoms. The most common SIBO symptoms, present in more than two-thirds of affected patients, are:
- Abdominal pain
- Bloating
- Gas
- Abdominal distension
- Flatulence
- Diarrhea
However, it's also possible for SIBO to cause many other symptoms that may not necessarily be associated with poor gut health, such as:
- Headaches
- Joint pain
- Brain fog
- Fatigue
- Sleep disturbances
- Skin rashes
- Restless legs
- Poor mood
Given the extent to which this wide variety of symptoms can disrupt daily activities and overall sense of well-being, SIBO has been linked to poorer health-related quality of life.
What Is an Elemental Diet?
The elemental diet (ED) is a hypoallergenic and anti-inflammatory liquid meal replacement beverage. It is often used in clinical practice as a medical formula to treat severe inflammatory digestive disorders, such as Crohn's disease.
The ED differs from other meal replacement formulas because it is "nutritionally complete" – it contains all the necessary nutrients humans need to live – and the ingredients are broken down into their most basic ("elemental") forms. Proteins, fats, and carbohydrates are broken down into their simplest building blocks: amino acids, short-chain triglycerides, and simple carbohydrates (glucose or maltodextrin). The formula also contains vitamins and minerals. (27)
The semi-elemental diet is a variation of the full ED. Its formula contains partially hydrolyzed proteins (amino acid chains) and medium-chain triglycerides. This composition makes semi-elemental diets more palatable and easier to tolerate than EDs while still offering the benefit of reduced digestive workload.
How the Elemental Diet Works for SIBO
The ED treats SIBO by feeding the affected patient but starving the overgrown bacteria. The nutrients are absorbed quickly within the first portions of the small intestine before bacteria can ferment (digest) them for their own benefit. During an ED protocol, the patient will use the ED as their only source of nutrition for 2-3 weeks. (44)
Compared to prescription or herbal antibiotics, ED prescriptions are far less common in clinical practice, likely due to their associated cost and restrictive nature. However, a 2016 primary care review suggested the ED as a plausible SIBO treatment option, given its association with improved SIBO breath test results and gastrointestinal symptoms in patients who followed it.
This recommendation is backed by a combination of empirical and scientific evidence that supports using the ED to treat SIBO in clinical practice.
The most widely referenced study used in support of the ED for SIBO is a 2004 study that involved 93 people with IBS and positive SIBO lactulose breath tests (LBT). After adhering to the ED for 14 days, 80% of patients had a normal LBT. Those who still had abnormal LBT results continued the diet for an additional week and repeated the LBT. At the end of the 21-day trial, 85% of participants had normal LBT results, indicating an eradication of SIBO. Normalization of the LBT also coincided with symptom improvement.
Implementing the Elemental Diet: A Practitioner's Guide
Implementing the elemental diet in clinical practice involves several key steps to ensure patient safety, compliance, and effectiveness. Here is a guide for practitioners:
Step 1: Patient Assessment
Determine if the ED is appropriate for the patient. Screen for any contraindications that would disclude the ED from being a reasonable treatment option for your patient. These include:
- Diabetes
- Fungal overgrowth
- History of an eating disorder
Step 2: Patient Preparation and Education
Educate the patient on the purpose and process of the elemental diet. Explain that this liquid-only diet involves drinking a formula of pre-digested nutrients designed to minimize digestive effort and absorption issues.
Despite these digestive benefits, following a liquid-only diet for an extended period presents mental and emotional challenges that the patient should be prepared for. Additionally, one of the major drawbacks that patients report with the ED is its unpalatable taste, which can make it difficult to adhere to. (28)
Patients should continue taking all essential medications during the protocol. Supplements are optional and can be used as needed to manage side effects. For example, electrolytes can be added to prevent dehydration if they begin to experience diarrhea, and Vitamin C and magnesium can be used to treat constipation.
Step 3: Diet Selection
Recommend a prescription or nonprescription commercial ED formula.
Alternatively, patients can make their formula themselves at home, which tends to be less expensive than the commercial options. Example recipes can be found here.
Calculate the patient's daily caloric needs based on their age, weight, activity level, and clinical condition. This determines how much formula the patient will need to drink daily to meet their daily caloric goals.
Step 4: Monitoring and Support
Healthcare providers should be readily available to their patients during the ED protocol to monitor their clinical response, including symptom improvement and side effects, and address any questions that arise.
Common side effects of the ED include (28, 44):
- Increased hunger and weight loss, when not drunk in sufficient amounts
- Digestive symptoms: bloating, diarrhea, abdominal pain, nausea, less frequent bowel movements
- Headaches
- Fatigue
- Muscle and joint pain
- Mood swings
- Fungal overgrowth
Step 5: Assess Treatment Efficacy
The 2004 study referenced above set the ED's standard treatment timeframe of 14-21 days. Once the ED is completed, SIBO status can be evaluated by repeating the SIBO breath test or assessing the patient's clinical symptoms. When treating based on symptoms, many doctors will continue treatment until the patient reports an 80-90% improvement.
Transitioning Off the Elemental Diet
The ED is not designed to be a long-term diet. Once the patient has completed their protocol, they should be guided in gradually reintroducing solid foods back into their diet to prevent digestive upset.
Here is an example of a 3-day transition diet that I will recommend to my patients:
- Day 1: eat a low-fiber diet consisting of meats, eggs, fats, white rice, and (if tolerated) lactose-free dairy
- Day 2: add cooked low-FODMAP vegetables, such as green beans, green bell peppers, and carrots (32)
- Day 3: add low-FODMAP fruits, such as melon, blueberries, or oranges (32)
- Day 4: return to regular diet
An alternative approach would be to follow a half-elemental diet, which involves replacing one to two meals per day with an elemental shake, providing approximately 50% of daily caloric intake. The remaining meals consist of a healthy, whole-food diet. This approach better allows for long-term use of the ED and offers a balanced way to support digestive health while maintaining the benefits of regular whole foods.
Dietary strategies can also be worked into a long-term SIBO prevention plan. Popular diets for the treatment and prevention of SIBO include (15):
- Low-FODMAP Diet
- Specific Carbohydrate Diet (SCD)
- SIBO Bi-Phasic Diet (SIBO B-PD)
- Gut and Psychology Syndrome (GAPS) Diet
- Cedars-Sinai Diet (CSD)
These dietary plans are all variations of elimination diets that aim to limit the intake of fermentable carbohydrates that bacteria thrive on, thereby reducing their population. By doing so, SIBO diets help to minimize clinical symptoms. (15)
Practitioner Tips for Maximizing Success
Here are tips that can help your patients successfully follow an elemental diet:
Take the time to properly prepare your patients before they start the ED: Before your patient begins their ED, have them schedule an appointment with ample time for you to explain the procedure and answer all of their questions.
Modify the ED: Consider prescribing a semi-elemental diet or prescribing a shortened ED protocol to kick-start SIBO treatment. Then, use antibiotics or herbal antimicrobials to finish eradicating SIBO.
Prevent fungal overgrowth: Because intestinal fungal overgrowth is a common side effect of the ED, many practitioners will prescribe prophylactic antifungals for their patients during the ED protocol. Drinking the formula through a straw can also help prevent oral thrush (yeast overgrowth in the mouth).
Make the ED more palatable: To improve the taste of the ED formula, one of its major deterring factors, recommend a flavored commercial ED or semi-elemental formula to your patient. Drinking the beverage cold, such as by blending the formula with ice, can also help improve taste.
Make the ED more affordable: Patients can save money by homemaking their ED formula instead of buying commercial products.
Regulate blood sugar: The ED's high glucose load can lead to fast peaks and dips in blood sugar, contributing to symptoms like fatigue, headache, and irritability. To help stabilize blood sugar, instruct patients to sip on their elemental shake throughout the day instead of drinking three "meals."
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Key Takeaways
- SIBO is a gastrointestinal condition that mimics the symptoms of IBS and requires a reduction of bacterial overgrowth for treatment.
- The elemental diet is a hypoallergenic liquid formula that starves bacteria and reduces inflammation in the intestines. It can be used to treat SIBO and its associated symptoms.
- Successfully prescribing the ED to patients involves many logistical elements. Patient education and providing tools to navigate obstacles that commonly arise with an ED protocol help patients complete their diet. Most patients who complete the ED find that the challenges were worth it.
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