4 Gut Health Tests That Patients Ask For The Most

Gut health influences everything from digestion and immunity to mental health and energy levels. As awareness of the gut-brain connection and the importance of a balanced microbiome grows, so does the demand for accurate and comprehensive gut health assessments. Certain gut health tests have become particularly popular among patients seeking to understand and optimize their digestive health.

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Understanding Gut Health

What does "gut health" mean?

The gut refers to the gastrointestinal tract – the system of organs from mouth to anus that food and liquids pass through as they are digested, absorbed, and eliminated from the body.

The large intestine is home to trillions of microorganisms, including bacteria, viruses, and fungi, collectively known as the gut microbiota. These microbes play roles in digesting food, synthesizing vitamins, regulating the immune system, and even influencing mood and cognitive function. 

Optimal Gut Health

One of the primary indicators of gut health is the absence of digestive discomfort. Individuals with a healthy gut typically experience regular bowel movements once to twice daily without symptoms such as bloating, gas, constipation, or diarrhea. The quality and frequency of these bowel movements can be assessed using the Bristol Stool Chart, where types 3 and 4 (smooth, sausage-like stools) are considered ideal.

Beyond digestive comfort, if we take a microscope to the digestive tract, we'd see a robust and diverse microbiome and an intact intestinal barrier in a healthy gut. Diversity in gut bacteria enhances the resilience of the gut ecosystem, promotes metabolic flexibility, and protects against pathogenic overgrowth and infection. 

An intact intestinal barrier is a multi-layered structure that includes the gut microbiota, mucus layer, epithelial cells, and immune cells, all working together to prevent harmful substances like bacteria and toxins from entering the body while allowing the absorption of nutrients and fluids.

Optimal gut health is also linked to systemic effects, including improved metabolism, immune function, nervous system functioning, and hormonal balance.

Symptoms of Poor Gut Health

An imbalance in the microbiome (dysbiosis) and disruption of the intestinal barrier (increased intestinal permeability or "leaky gut") are linked to various gastrointestinal and extraintestinal conditions, such as: 

• Irritable bowel syndrome (IBS)
• Autoimmune disease
• Heart disease
• Obesity
• Thyroid dysfunction
• Mood disorders.

Any of the following symptoms can be an indicator of poor gut health:

• Constitutional: fatigue, unintentional changes in weight
• Gastrointestinal: bloating, gas, constipation, diarrhea, acid reflux, food intolerances
• Skin: rashes, acne, itching (49) 
• Immunological: allergies, inflammation
• Endocrine: irregular periods, hot flashes, low libido, hair loss, weight gain, fertility issues (44) 
• Neurological: brain fog, difficulty concentrating, headaches

Factors Affecting Gut Health

Both modifiable and unmodifiable factors can affect gut health, including (48):

• Method of birth delivery (vaginal versus cesarean delivery)
• Method of infant feeding (formula versus breastfeeding)
• Age
• Diet
• Medications
• Stress
• Exposure to environmental toxins
• Underling medical conditions

Top 4 Gut Health Tests in Functional Medicine

These are the top four gut health tests commonly used in integrative health evaluations.

1. Comprehensive Stool Analysis (CSA)

A CSA examines various aspects of the stool to assess gut health. While each specific test may differ slightly in what it analyzes, the biomarkers included in a CSA can generally be grouped under the following categories:

• Digestion and absorption
• Gut microbiome
• Microbiome metabolites
• Inflammation
• Infection

When to Use It

Patients experiencing chronic digestive issues such as bloating, gas, abdominal pain, diarrhea, or constipation may benefit from a CSA. 

It's also useful for individuals with unexplained symptoms or health conditions that might be linked to gut health:

• Chronic fatigue
• Skin problems
• Mental health disorders
• Metabolic disorders
• Autoimmune disease
• Asthma
• Allergies
• Fibromyalgia
• Neurodegenerative diseases
• Hormonal imbalances

Understanding Results

• Digestion and Absorption: Identifies digestive enzyme deficiencies and malabsorption syndromes that can contribute to digestive symptoms.
• Gut Microbiota Composition: Identifies beneficial vs. harmful bacteria and detects dysbiosis.
• Pathogens: Detects harmful organisms that could be causing infections.
• Short-Chain Fatty Acids: Assesses bacterial fermentation of non-digestible carbohydrates as markers of gut health, metabolism, and immune function.
• Inflammation Markers: Elevated levels indicate gut inflammation.

Benefits

CSA provides a comprehensive overview of gut health, allowing for targeted interventions such as probiotics, dietary adjustments, or antimicrobial therapies to restore balance and alleviate symptoms.

Limitations

• Cost: CSAs can be expensive and may not be covered by insurance, limiting accessibility for some patients.
• Variability in Testing Methods: Different laboratories may use varying methodologies and reference ranges, making comparing results across different tests difficult.
• Sample Handling Sensitivity: Stool samples are sensitive to contamination and require proper handling and timely analysis to ensure accurate results. Delays or improper storage can affect the integrity of the sample.

Examples of CSA Tests

• GI Effects Comprehensive Profile by Genova Diagnostics
• GI-MAP by Diagnostic Solutions
• GI360 by Doctor's Data

2. SIBO Breath Test 

As the name suggests, small intestinal bacterial overgrowth (SIBO) is an overgrowth of bacteria in the small intestine. As our understanding of SIBO has expanded, three distinct subtypes of SIBO have been identified, including:

• Hydrogen-dominant SIBO
• Intestinal methanogen overgrowth (IMO)
• Intestinal sulfide overproduction (ISO)

A SIBO breath test assesses the levels of gases produced by bacteria in the intestines after consuming a sugar substrate to diagnose SIBO.

When to Use It

This test is ideal for patients presenting with symptoms like bloating, excessive gas, abdominal discomfort, diarrhea, or constipation, which are suggestive of SIBO. 

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It's also considered for individuals who have not responded to standard treatments for irritable bowel syndrome (IBS), as research indicates nearly 80% of those with IBS have underlying SIBO as a cause of their symptoms.

Understanding Results

• Elevated Hydrogen Levels: Hydrogen levels that rise at least 20 ppm from baseline within the first 90 minutes of the test are diagnostic for hydrogen-dominant SIBO (41). 
• Elevated Methane Levels: A methane level of 10 ppm or higher at any time point during the test is diagnostic for IMO (40).  
• Elevated Hydrogen Sulfide Levels: A hydrogen sulfide level of at least 3 ppm at any time point during the test is diagnostic for ISO (2). 

Benefits

Diagnosing SIBO allows for appropriate treatment, which may include specific antibiotics or herbal antimicrobials, dietary modifications (like the low FODMAP diet), and prokinetics. 

Limitations

• False Positives/Negatives: The test can sometimes yield false positives or negatives due to factors like rapid transit time, improper test preparation, and the type of substrate used.
• Preparation Requirements: Patients must adhere to strict dietary and preparation guidelines before the test, which can be inconvenient and may affect compliance.

Examples of SIBO Breath Tests

• SIBO - 3 Hour by Genova Diagnostics
• SIBO/IMO Glucose Breath Test by Commonwealth Diagnostics International, Inc.
• trio-smart SIBO Breath Test by Gemelli Biotech

3. Food Sensitivity Testing

Food sensitivities are a type of immune-mediated adverse food reaction. Unlike food allergies, which involve IgE antibodies and cause immediate and potentially life-threatening reactions, food sensitivities are mediated by non-IgE immune proteins. They can take up to 72 hours to manifest after exposure to the culprit food.

Food sensitivity panels evaluate the immune system's response to isolated food proteins. Common biomarkers used in these tests include:

• Immunoglobulin A (IgA): Antibodies primarily found in mucous membranes, including the gut lining.
• Immunoglobulin G (IgG): The most abundant type of antibody in the blood involved in the body's long-term (adaptive) immune response.

When to Use It 

This test can benefit patients with unexplained symptoms or those who suspect certain foods may be triggering their symptoms but have been unable to identify them through observation alone.

Understanding Results

• Elevated IgG/IgA Antibodies: Suggests a sensitivity to particular foods, which may need to be eliminated or reduced in the diet.
• Normal Levels: Indicates no significant immune response to the tested foods.

Benefits

Identifying trigger foods helps create personalized dietary plans that reduce inflammation, improve gut barrier function, and alleviate symptoms.

Limitations

• Lack of Standardization: No universally accepted standard for interpreting IgG/IgA levels leads to variability in results and interpretations between different testing companies.
• Clinical Relevance: Elevated IgG antibodies may indicate exposure rather than true sensitivity, and their clinical significance is still a topic of debate among healthcare professionals.
• False Positives/Negatives: The test can produce false positives, leading to unnecessary dietary restrictions, or false negatives, missing actual sensitivities.

Examples of Food Sensitivity Tests

• foodANALYZER IgG Food Sensitivity by Access Med Labs
• 96 General Food Panel: IgA/IgG/IgG4 by US BioTek
• FIT 132 by KBMO Diagnostics 

4. Intestinal Permeability Test (Leaky Gut Test)

There are two main laboratory methods for quantifying intestinal permeability. 

The first is called a lactose-to-mannitol ratio (LMR) urine test. The LMR test evaluates intestinal permeability by measuring the ratio of two sugar molecules – lactulose and mannitol – in the urine after oral ingestion. Lactulose is a larger molecule that does not typically pass through the intestinal barrier, while mannitol is smaller and can pass more easily. When leaky gut is present, more lactulose can pass through the gut barrier and will be excreted by the kidneys. (17) 

The second test measures fecal zonulin, which is a protein that modulates the permeability of tight junctions between cells in the intestinal lining (17). 

When to Use It

This test is recommended for patients with chronic signs and symptoms that are linked to increased intestinal permeability, including:

• Bloating
• Gas
• Abdominal pain
• Abnormal bowel habits
• Multiple food intolerances
• IBS
• Inflammatory bowel disease
• Celiac disease
• Chronic fatigue
• Joint pain
• Acne
• Depression 

Understanding Results

• Elevated LMR and Zonulin: Indicates increased intestinal permeability
• Normal LMR and Zonulin: Suggest a healthy and intact gut barrier

Benefits

Detecting leaky gut allows for interventions aimed at healing the gut barrier, such as specific dietary changes, supplements (like L-glutamine or zinc), and lifestyle modifications to reduce inflammation and restore gut integrity.

Limitations

• Test Sensitivity and Specificity: The accuracy of the tests can vary, and they may not detect all forms of intestinal permeability or differentiate between different causes.
• Preparation Requirements: The accuracy of LMR urine tests depends on patients following specific preparation protocols, which can be inconvenient and affect compliance. 
• Variability: Factors such as hydration status, recent food intake, individual gut flora, and stress can affect test outcomes.

Examples of Intestinal Permeability Tests

• Intestinal Permeability Assessment by Genova Diagnostics  
• Zonulin by Diagnostic Solutions

Additional Testing Considerations

Each of these gut tests offers unique insights into different aspects of gut health. When choosing the right test, healthcare providers should consider the patient's specific symptoms, medical history, and health goals. A combination of these tests often offers the most comprehensive understanding of gut health.

Sometimes, test results indicate the need for additional diagnostic testing and imaging. For example, elevated calprotectin measured with a CSA requires additional workup for inflammatory bowel diseases like celiac disease, IBD, or cancer with additional blood work, stool testing, and imaging. 

Benefits of Gut Health Testing in Functional Medicine

Gut health testing in functional medicine offers numerous advantages:

• Personalized Treatment Plans: Tests provide detailed insights, allowing for individualized interventions that address the root causes of gut issues.
• Early Detection of Imbalances: Identifying problems early prevents the escalation of digestive issues into more severe health conditions.
• Improved Patient Outcomes: Testing leads to targeted treatments, resulting in better symptom management, enhanced quality of life, and overall health improvement.
• Holistic Approach: Gut health tests align with the functional medicine philosophy of treating the whole person, considering multiple factors that influence health.

FAQs

How often should gut health tests be performed? 

The frequency of testing depends on individual health conditions and treatment plans. Generally, follow-up tests are recommended after implementing dietary or therapeutic interventions to monitor progress and make necessary adjustments.

Can gut health tests diagnose food allergies? 

While food sensitivity testing can identify immune-mediated food reactions, it does not diagnose true food allergies. For suspected food allergies, specific allergy tests like skin prick tests or IgE blood tests are more appropriate.

What should I do if my gut health test results are abnormal? 

Abnormal results should be discussed with a healthcare provider, who can recommend appropriate interventions such as dietary changes, supplements, probiotics, or medications to address identified issues and restore gut balance.

Are gut health tests covered by insurance? 

Coverage varies depending on the insurance provider and specific plan. Functional medicine tests are often considered elective and may not be covered. It's advisable to check with your insurance company and discuss potential out-of-pocket costs with your healthcare provider.

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Key Takeaways

• Gut health is a cornerstone of overall well-being, influencing digestion, immunity, mental health, and chronic disease risk. 
• A comprehensive stool analysis evaluates five key areas related to gastrointestinal health and function: maldigestion/absorption, inflammation, dysbiosis, metabolite imbalance, and infection.
• A SIBO breath test measures various gas levels to diagnose SIBO, a common cause of IBS symptoms.
• Food sensitivities are a type of delayed immune-mediated food reaction that can cause an array of digestive and extraintestinal symptoms.
• Intestinal permeability tests can quantify the extent to which the gut barrier has become compromised, adversely affecting digestion, nutrient absorption, and systemic inflammation.