With an estimated 179 million cases annually, acute diarrhea is one of the most common illnesses in the United States. Worldwide, acute diarrhea is a leading cause of death in children under four. Chronic diarrhea, lasting longer than four weeks, affects approximately 5% of the population. Virtually all people will experience some type of diarrhea at some point in their lives. Keep reading to learn about the causes of diarrhea and approaches that may help support digestive health.
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What Is Diarrhea?
Diarrhea is a gastrointestinal condition characterized by loose, watery bowel movements. In addition, loose stools may occur more frequently than usual. Diarrhea is classified by how long it lasts. Acute diarrhea lasts less than two weeks, persistent diarrhea lasts between two and four weeks, and chronic diarrhea persists longer than one month. Acute diarrhea is the second most commonly reported illness in the United States. Severe diarrhea can lead to dehydration, electrolyte imbalances, and shock, particularly in vulnerable populations. (19)
Diarrhea Signs & Symptoms
The main symptom of diarrhea is passing loose, watery stools, often three or more times daily. However, depending on the cause, diarrhea may also be accompanied by at least one of the following symptoms (35):
- Fecal urgency
- Blood and mucus in stool
- Abdominal pain and cramping
- Bloating
- Gas
- Nausea and vomiting
- Change in appetite
- Fever and chills
- Weight loss
What Causes Diarrhea?
The differential diagnosis for diarrhea is extensive. The chronicity of diarrhea will help to narrow the differential, as acute and persistent diarrhea have causes that differ from those of chronic diarrhea.
The leading causes of acute and persistent diarrhea are infections, traveler's diarrhea, and medication/supplement side effects. Viral, bacterial, and parasitic infections can cause diarrhea. Traveler's diarrhea is caused by consuming food or water contaminated by a pathogenic organism; it is most commonly acute, but some parasitic infections can go undetected, causing more chronic diarrhea. (35)
Many medications and supplements can cause diarrhea as a side effect. Antibiotics, antacids, laxatives, and chemotherapy drugs are examples of medicines that may contribute to diarrhea (35). Magnesium, high doses of vitamin C, aloe vera, and fish oil are common supplements that might lead to loose stool.
Many gastrointestinal pathologies are responsible for causing loose stool, including inflammatory bowel disease (IBD), irritable bowel syndrome (IBS-D), celiac disease, fat malabsorption due to gallbladder or pancreatic disease, small intestinal bacterial overgrowth (SIBO), lactose intolerance and other adverse reactions to foods, and colon cancer.
Extraintestinal disorders can also cause diarrhea as a predominant symptom. Examples include hyperthyroidism, Addison's disease, endometriosis, and diabetes.
Functional Medicine Labs to Test for Root Cause of Diarrhea
Many functional medicine tests can be ordered to assess the health and function of the gastrointestinal tract and determine the root cause of loose stool. Here are some of the most commonly ordered tests during a diagnostic evaluation of diarrhea.
Blood Work
Routine blood work is standard in working up diarrhea, especially in chronic cases.
A complete blood count (CBC) with differential can screen for signs of infection. Specific patterns in white blood cell distributions can differentiate between the chronicity and type of infection. Additionally, inflammatory bowel diseases may lead to gastrointestinal bleeding, leading to anemia, which can be diagnosed with this panel.
A comprehensive metabolic panel (CMP) assesses blood sugar, electrolytes, pH, and the liver, gallbladder, and kidney health. This thorough evaluation can indicate pathologies that may contribute to and result from diarrheal conditions.
Poorly managed or undiagnosed diabetes mellitus can cause nerve damage and intestinal dysmotility, potentially leading to diarrhea (5). Hemoglobin A1c (HbA1c) is a three-month average of blood sugar most commonly used to diagnose diabetes.
A hyperthyroid state increases the body's metabolic rate and can contribute to diarrhea through various mechanisms, which include increasing intestinal motility and altering fluid absorption in the intestines. Hyperthyroidism can be screened for with a thyroid panel, including TSH, free T4, and free T3.
While endoscopy is required for definitive diagnosis, a celiac panel is routinely ordered first as a less invasive and expensive means of ruling in the diagnosis of celiac disease.
Comprehensive Stool Test
Comprehensive stool tests measure many gut-specific biomarkers helpful in assessing the health and function of overall gut function, integrity, and overall health. The biomarkers can be organized into broad categories that help assess digestive function, inflammation and immune function, infections, and intestinal dysbiosis. Comprehensive stool tests include conventional markers, such as pancreatic elastase, fecal fat, calprotectin, and stool cultures; however, they also go beyond these traditional markers to detect more subtle imbalances in intestinal permeability, digestion, and the microbiome, which standard tests cannot pick up.
SIBO Breath Test
Hydrogen- and hydrogen sulfide-dominant subtypes of SIBO are strongly associated with diarrheal presentations. Food poisoning, a common cause of acute diarrhea, can induce immunological changes that generate small intestinal dysmotility, resulting in SIBO and persistent/chronic diarrhea even after the inciting infection has been addressed. (8)
The trio-smart breath test is the only SIBO test on the market capable of directly measuring all three gaseous byproducts (hydrogen, methane, and hydrogen sulfide) associated with the three types of SIBO.
Adverse Food Reactions
Adverse food reactions include allergies, intolerances, and sensitivities. It is important to differentiate between them to ensure appropriate management and strategies.
Food allergies are IgE-immune mediated reactions that mount an immediate allergic immune response, associated with mild to severe symptoms like hives, shortness of breath, and anaphylaxis. Food allergies can be diagnosed with a blood test that measures IgE antibodies to specific food proteins.
Food sensitivities are IgG-immune mediated delayed reactions that can occur up to 72 hours after exposure to a food trigger. Food sensitivities commonly manifest as gastrointestinal symptoms, including diarrhea, but can also cause extraintestinal symptoms, such as headaches, joint pain, and skin rashes. A panel that measures IgG antibodies against food proteins helps to identify food sensitivities.
Food intolerance refers to difficulty digesting or metabolizing certain components of food or food additives. Food intolerances are not immune-mediated and often result from enzyme deficiencies. Tests that can help identify food intolerances include the lactose and fructose malabsorption breath tests to identify lactose and fructose intolerance, respectively. (27)
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Functional Medicine Approaches for Digestive Health
A functional medicine approach will vary depending on the underlying factors contributing to gastrointestinal dysfunction. Underlying health conditions, such as hyperthyroidism or diabetes mellitus, should be addressed with the guidance of a healthcare provider. The rest of this article will primarily emphasize a functional medicine approach to supporting digestive health, including dietary modifications and supplements that may help reduce intestinal inflammation and optimize the diversity and abundance of the gut microbiome.
Therapeutic Diet and Nutrition Considerations for Digestive Health
A bland or BRAT (bananas, rice, applesauce, and toast) diet is generally recommended during acute diarrhea to remove difficult-to-digest and irritating foods that can aggravate acute gastrointestinal symptoms. Staying well hydrated and drinking electrolytes is equally important to help maintain hydration and electrolyte balance. (38)
For persistent or chronic diarrhea, an excellent place to start is with a gut-supportive elimination diet designed to reduce or remove foods that may irritate the gut lining and contribute to dysbiosis, support gut integrity, nourish beneficial gut bacteria, and help manage inflammation. An anti-inflammatory diet, tailored to accommodate specific food allergies, intolerances, and sensitivities, should emphasize whole foods that contain a healthy ratio of complex carbohydrates, unsaturated fats, lean proteins, and fiber.
Specific foods can be incorporated to help support gut health naturally with functional nutrition. Probiotic foods, such as kimchi and sauerkraut, contain live cultures of beneficial microorganisms that may help beneficially alter the microbiota's composition and displace less beneficial organisms, enhancing the integrity of the gut barrier and modulating immune activity. Prebiotic foods contain nondigestible compounds that can modulate the composition and activity of the gut microbiota. Examples of prebiotic foods include bananas, onions, and legumes.
Studies have shown that collagen may help reduce digestive symptoms, support the intestinal lining, and protect the gut from damage by pro-inflammatory molecules. Collagen is found naturally in animal products that contain high amounts of connective tissue. Bone broth is an excellent source of collagen. (15)
Soluble fiber absorbs water in the digestive tract, potentially firming stool and supporting its transit through the intestines. Pectin is a soluble dietary fiber in fruits, vegetables, legumes, potatoes, and sugar beets. Substantial evidence supports that pectin has prebiotic effects (promoting a favorable microbiota composition), may delay gastric emptying, support IBS-D, and help manage stool frequency. (28)
Supplements Considerations for Digestive Health
The following considerations can be used as a generic template for doctors to discuss with their patients as part of a 5R support protocol. A 5R protocol aims to support and maintain the digestive tract by removing potential irritants, replacing important digestive enzymes, reinoculating the gut with healthy microbes, supporting the gut lining, and rebalancing gut function with healthy lifestyle habits. Supplements used during a protocol may be dosed simultaneously, or staggered in phases. Treatment protocols should be customized based on the patient's medical history, laboratory findings, and preferences.
Biocidin®
Biocidin® is a broad-spectrum formula that combines 18 botanical extracts and essential oils to support a healthy microbiome. The botanicals act as natural alternatives to antibiotics and antifungals to help manage dysbiotic patterns and modulate the immune system to support healthy inflammation levels in the gastrointestinal tract. (3)
Dose: 1-2 capsules 2-3 times daily
Duration: 4-6 weeks
Probiotics
A variety of commercial probiotic products are available. Systematic analyses suggest the potential efficacy of various probiotic species in supporting digestive health, with improvements noted as soon as the second day of use (2, 24). The benefits of probiotics are strain-specific, meaning different strains have different effects and potential benefits. Therefore, when selecting a probiotic product, it's important to consider the specific strains in the formula to achieve the desired health outcome.
Dose & Duration: will vary depending on individual needs and health goals
GI Response
Combination products, such as GI Response by Innate Response, contain a variety of natural ingredients and botanicals that may help soothe inflammation and support the healing of the intestinal lining. Ingredients including L-glutamine, aloe vera, and marshmallow root are commonly considered for celiac disease and IBD, common contributors to chronic diarrhea. (30)
Dose: 1 scoop mixed in water twice daily
Duration: 4-6 weeks
Digestive Enzymes
Supplemental digestive enzymes can help support the digestion of food and the absorption of essential nutrients. Digestive enzyme formulas should be based on the patient's needs, often guided through patient-reported history of food intolerances or functional test results. Small studies and case reports have indicated that enzymatic therapy with meals can help manage food-related gastrointestinal symptoms, including diarrhea.
When to Retest Labs
A 5R protocol often takes at least 3-6 months to complete. Repeat labs may be ordered during the process to ensure the patient is meeting specific goals, like addressing an identified imbalance, for example. However, repeat labs are generally postponed until after the protocol is finished. Retesting labs may not be required, as improvement in bowel habits and food tolerance can be used to monitor progress.
Learning More About Digestive Health
- Magazine Article: IBS vs. IBD: Know the Symptoms
- Magazine Article: A Functional Medicine Approach to Loose Stool in Pediatrics
- Live Class: Mastering Gut Microbiome Testing: A Major Weapon Against Chronic Illness
- Podcast: Small Intestinal Bacterial Overgrowth (SIBO) The Root Cause of Your Gut Symptoms with Craig Strasnick
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Summary
Diarrheal illness is common, affecting most people at some point during their lives. While diarrhea may be self-resolving, functional medicine approaches can help support the gut-healing process with nutrition and supplements. Specialty labs measure functional markers of gut health and function to identify underlying factors contributing to digestive discomfort more thoroughly. These labs help to personalize recommendations for improved health outcomes.
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