Ulcerative Colitis: Causes, Testing, Diet and Functional Medicine Support
Ulcerative colitis is a chronic inflammatory bowel disease that affects the inner lining of the colon and rectum. It usually follows a pattern of active flares and periods of remission. Common symptoms include diarrhea, blood or mucus in the stool, urgency, abdominal pain, fatigue and unintentional weight loss.
Although ulcerative colitis primarily affects the large intestine, its effects are not always limited to the digestive system. Some people may also develop problems involving the joints, skin, eyes, liver, bile ducts, bones or blood.
The exact cause of ulcerative colitis remains unknown. Current understanding suggests that it develops through a complex interaction between genetic susceptibility, immune dysregulation, alterations in the gut microbiome, impaired intestinal-barrier function and environmental exposures.
What Causes Ulcerative Colitis?
There is no single cause of ulcerative colitis. Several interacting factors appear to contribute to its development.
1. Genetic susceptibility
Many genetic susceptibility loci have been associated with inflammatory bowel disease, including multiple loci associated with ulcerative colitis. These genes may affect:
● Regulation of the immune response
● Integrity of the intestinal epithelial barrier
● Recognition and handling of intestinal microorganisms
● Autophagy and cellular defense
● Oxidative-stress and mitochondrial pathways
Having a genetic susceptibility does not mean that a person will necessarily develop ulcerative colitis. It may, however, influence how the immune system and intestinal barrier respond to environmental or microbial triggers.
2. Immune dysregulation
Ulcerative colitis involves an exaggerated and poorly regulated immune response within the large intestine. The immune system reacts abnormally to intestinal microorganisms and other contents of the bowel, resulting in persistent inflammation and damage to the colonic mucosa.
3. Gut dysbiosis and intestinal-barrier dysfunction
The gut microbiome is the community of microorganisms living inside the gastrointestinal tract. Research has consistently identified changes in the microbiome of people with ulcerative colitis, although no single microbial pattern is present in every patient.
Reported findings include:
● Reduced overall microbial diversity
● Reduction in beneficial butyrate-producing bacteria
● Lower levels of organisms such as Faecalibacterium prausnitzii and Roseburia hominis
● Alterations in Firmicutes and Bacteroidetes
● Increased abundance of some potentially inflammatory members of Proteobacteria and Enterobacteriaceae
These changes may reduce the production of beneficial short-chain fatty acids such as butyrate. They may also impair the intestinal epithelial barrier, increase intestinal permeability and promote inflammatory immune activity.
It remains important to recognize that dysbiosis is not identical in every patient. A commercial stool microbiome result alone cannot diagnose ulcerative colitis.
4. Environmental factors
Environmental factors may influence susceptibility, symptoms or disease activity. These include:
● Dietary patterns
● Previous or repeated antibiotic exposure
● Non-steroidal anti-inflammatory medications
● Oral contraceptive exposure
● Air and water pollution
● Smoking history
● Psychological stress
Stress is not considered the sole cause of ulcerative colitis, but it may affect gut–brain signaling, immune regulation, intestinal permeability and symptom severity.
What Conditions Can Resemble Ulcerative Colitis?
It is essential to exclude infection and other causes of colitis before confirming the diagnosis. Important differential diagnoses include:
● Bacterial, viral or parasitic colitis
● Clostridioides difficile infection
● Crohn’s disease
● Microscopic colitis
● Ischemic colitis, particularly in the appropriate clinical setting
● Medication-induced colitis
● Celiac disease
● Food-related intolerance
● Irritable bowel syndrome when symptoms occur without objective intestinal inflammation
Tests Used in the Evaluation of Ulcerative Colitis
Blood tests
The initial laboratory assessment may include:
● Complete blood count
● Electrolytes and kidney function
● Liver enzymes, bilirubin, albumin and total protein
● C-reactive protein and erythrocyte sedimentation rate
● Iron studies, ferritin and transferrin saturation
● Vitamin D
● Vitamin B12 and folate when clinically indicated
These tests help identify inflammation, anemia, blood loss, nutritional deficiencies, dehydration and possible liver or biliary involvement.
p-ANCA and ASCA
The antibody more commonly associated with ulcerative colitis is p-ANCA, while ASCA is more commonly associated with Crohn’s disease. A p-ANCA-positive and ASCA-negative pattern may support ulcerative colitis, whereas an ASCA-positive and p-ANCA-negative pattern may support Crohn’s disease.
These markers cannot independently diagnose or exclude either condition. They must be interpreted alongside the clinical presentation, stool tests, colonoscopy and biopsy findings.
Stool testing
Stool investigations may include:
● Testing for bacterial pathogens
● Testing for Clostridioides difficile
● Parasite testing when appropriate
● Fecal calprotectin
● Fecal lactoferrin
Fecal calprotectin and lactoferrin can help detect and monitor intestinal inflammation. They are not specific to ulcerative colitis and cannot identify its cause by themselves.
Comprehensive stool profiles, including tests such as GI-MAP, may be used in a functional medicine assessment to explore potential pathogens, digestive markers and patterns of dysbiosis. However, these tests do not establish the diagnosis of ulcerative colitis and do not replace colonoscopy and biopsies.
Colonoscopy and biopsies
Colonoscopy with systematic biopsies is central to diagnosing ulcerative colitis. It helps determine the extent and severity of inflammation, distinguishes ulcerative colitis from other forms of colitis and provides a baseline for appropriate surveillance.
Assessing for SIBO
Small-intestinal bacterial overgrowth may coexist with inflammatory bowel disease and can contribute to bloating, excessive gas, abdominal discomfort, diarrhea or altered bowel habits.
When symptoms suggest SIBO, a glucose or lactulose hydrogen-and-methane breath test may be considered. Some protocols collect breath samples over two to three hours. A positive result should be interpreted in the context of symptoms, intestinal transit and the limitations of breath testing.
Conditions Associated With Ulcerative Colitis
Ulcerative colitis may be associated with conditions affecting other organs, including:
● Joints: peripheral arthritis, sacroiliitis or ankylosing spondylitis
● Skin: erythema nodosum or pyoderma gangrenosum
● Eyes: episcleritis or uveitis
● Liver and bile ducts: particularly primary sclerosing cholangitis
● Bones: osteopenia or osteoporosis
● Blood: iron-deficiency anemia, anemia of chronic inflammation or both
Because ulcerative colitis is associated with primary sclerosing cholangitis, evaluation may include alkaline phosphatase, gamma-glutamyl transferase, alanine aminotransferase, aspartate aminotransferase and bilirubin. Persistent cholestatic abnormalities require further medical assessment.
Bone health should also be considered according to disease duration, nutritional status, menopausal status, vitamin D level and previous corticosteroid exposure.
A Functional Medicine Approach to Ulcerative Colitis
A functional medicine assessment looks beyond intestinal symptoms alone. It considers factors that may influence inflammation, gastrointestinal function, nutritional status and quality of life. The objective is not to replace the patient’s gastroenterology care or prescribed medication. It is to identify potentially modifiable contributors and provide individualized support alongside appropriate medical treatment.
1. Identify nutritional deficiencies
Chronic intestinal inflammation, blood loss, reduced food intake and restrictive diets may contribute to deficiencies. Assessment may include iron status, vitamin D, vitamin B12, folate, albumin and other nutrients according to the individual clinical picture.
2. Personalize the diet
There is no single ulcerative colitis diet suitable for every patient or every stage of the disease.
Low-residue diet
A temporary low-residue or low-fiber diet may be considered during an active flare when diarrhea, bleeding, urgency or abdominal pain is prominent. It is generally a short-term measure rather than a permanent eating pattern.
Specific Carbohydrate Diet
The Specific Carbohydrate Diet has been explored in inflammatory bowel disease. Small studies and clinical reports have described symptom improvement in some patients, but the evidence remains limited. It should therefore be individualized, monitored for nutritional adequacy and not presented as a guaranteed way to induce remission.
Low-FODMAP diet
A low-FODMAP diet may reduce overlapping functional symptoms such as bloating, gas and abdominal discomfort. Its main role is symptom management; it has not been established as a treatment for the underlying colonic inflammation. Because it is restrictive, the elimination phase should not continue unnecessarily.
3. Evaluate the microbiome and digestive function
When clinically appropriate, a broader evaluation may investigate infection, dysbiosis, SIBO, digestive function and bowel patterns. The relevance of each result should be determined in the context of disease activity, medications, symptoms and standard diagnostic findings.
4. Consider selected nutrients and botanical compounds
Adjunctive interventions discussed in integrative care include:
● Correction of vitamin D deficiency
● Curcumin
● Boswellia serrata
● Aloe vera
● Butyrate
● Omega-3 fatty acids
● Selected probiotics
Ginger, peppermint and chamomile may sometimes be used for their carminative, calming or antispasmodic effects. However, supplements and botanical products are not automatically safe for every patient. Their evidence, dose, quality, medication interactions and suitability during active disease must be assessed individually.
5. Probiotics
Probiotic effects are strain- and formulation-specific. The multi-strain preparation historically studied in ulcerative colitis is VSL#3, particularly the original De Simone formulation, currently marketed in some countries as Visbiome. Another studied probiotic is Escherichia coli Nissle 1917.
These products are not interchangeable with arbitrary commercial probiotics. Current evidence does not support using probiotics as a substitute for established treatment, although selected formulations have been studied as adjuncts in some patients with mild-to-moderate disease.
6. Stress management and complementary support
Stress-management strategies, mind–body practices and acupuncture may be considered as supportive measures for stress, pain and quality of life. They should not be used as replacements for assessment and treatment of active intestinal inflammation.
7. Fecal microbiota transplantation
Fecal microbiota transplantation has produced promising results in some ulcerative colitis trials, but outcomes vary according to donor selection, preparation, route and treatment protocol. Its role in ulcerative colitis remains specialized and investigational. It requires rigorous donor screening and medical supervision and should never be attempted at home.
The Central Principle: Individualized, Step-by-Step Care
Ulcerative colitis is not caused by one isolated problem, and it cannot be managed effectively through a single supplement or a universally prescribed diet. A careful plan should assess disease activity, exclude infection, identify complications and nutritional deficiencies, and then address modifiable factors in a logical sequence.
Functional medicine can offer a broader framework for examining gut health, nutrition, microbial balance and lifestyle factors. However, it should remain integrated with appropriate gastroenterology follow-up, colonoscopic surveillance and prescribed treatment.
If you have ulcerative colitis and would like a comprehensive functional medicine assessment, an individualized consultation can help review your symptoms, medical history, nutrition, laboratory results, digestive function and potential contributing factors. The aim is to build a structured, step-by-step plan that complements your existing medical care.
Book your consultation with Dr. Samar Shadly to begin a personalized assessment of your gut health and nutritional needs.
This article is intended for education and does not replace diagnosis, medical treatment or follow-up with a gastroenterologist. New or worsening rectal bleeding, severe abdominal pain, persistent fever, dehydration, abdominal distension or marked weakness requires prompt medical assessment.