Could my symptoms be caused by something beyond food intolerance?

Could My Symptoms Be Caused by Something Beyond Food Intolerance?

Yes, your symptoms could absolutely be caused by conditions beyond food intolerance, and a systematic evaluation is essential to identify the underlying cause before restricting your diet unnecessarily.

Primary Non-Food Causes to Consider

Autonomic Dysfunction and POTS

• Postural Orthostatic Tachycardia Syndrome (POTS) commonly causes GI symptoms that may be mistaken for food intolerance, including nausea, bloating, abdominal pain, and altered bowel habits 1
• Food-related symptom exacerbation in POTS is often due to splanchnic vasodilation (blood pooling in the abdomen after eating) rather than true food intolerance 1
• POTS should be considered if you experience dizziness, lightheadedness, rapid heartbeat, or fatigue that worsens with standing or after meals 1

Mast Cell Activation Syndrome (MCAS)

• MCAS can produce GI symptoms alongside systemic manifestations like flushing, hives, or breathing difficulties 1
• However, validated clinical tests for mast cell-mediated abdominal pain are lacking, and routine testing (serum tryptase, mast cell staining) is not recommended for isolated GI symptoms without evidence of generalized mast cell disorder 1

Psychological and Stress-Related Mechanisms

• Acute psychological stress consistently stimulates colonic motor activity, with significantly greater responses in IBS patients compared to healthy individuals 2
• This stress response is mediated through corticotropin-releasing factor (CRF), which increases colonic motility and induces abdominal pain 2
• Approximately 50% of meal-related pain occurs within 90 minutes of eating due to exaggerated colonic response to food rather than food intolerance itself 2
• Altered autonomic reactivity, particularly increased sympathetic activity, directly translates psychological stress into altered colonic transit and symptoms 2

Celiac Disease and Pancreatic Insufficiency

• Risk of celiac disease is elevated in patients with hypermobile Ehlers-Danlos syndrome (hEDS) and POTS compared to the general population 1
• Serological testing for celiac disease followed by endoscopic biopsies should be considered earlier in individuals with various GI symptoms, not just diarrhea 1
• Pancreatic insufficiency is common in celiac disease and can be treated with gluten-free pancreatic enzyme supplements 3

Thyroid Dysfunction

• Hypothyroidism presents with fatigue, cold intolerance, weight gain, cognitive dysfunction, and constipation 4
• TSH and free T4 should be ordered immediately if you have these symptoms 4

Secondary Considerations

Gastroparesis and GI Dysmotility

• Earlier testing of gastric motor functions may be reasonable in patients with coexisting POTS, as autonomic dysfunction predisposes to gastroparesis 1
• Gastroparesis can be caused by medications frequently used (sedatives, opioids), gastric hypoperfusion in shock, hyperglycemia, or vasopressor use 1

Microscopic Colitis and Inflammatory Bowel Disease

• Colonoscopy is indicated for persistent or recurrent diarrhea due to increased risk of microscopic colitis and inflammatory bowel disease 1
• These conditions can occur even in those with healed small intestinal mucosa 1

Small Intestinal Bacterial Overgrowth (SIBO)

• SIBO can be detected by breath testing and may contribute to persistent GI symptoms 1

Pelvic Floor Dysfunction

• Diagnostic testing (anorectal manometry, balloon expulsion test, defecography) should be considered for difficult bowel evacuation given high prevalence in certain populations 1

What Testing Should NOT Be Done Routinely

Avoid Unnecessary Food Testing

• There is insufficient research to support routine testing for carbohydrate maldigestion or malabsorption in the absence of specific clinical indicators 1
• Lactose or fructose intolerance testing is only indicated if you consume substantial amounts (>0.5 pint/280 ml) of milk daily or have specific symptom patterns 1
• Food skin tests or IgE blood tests alone are not diagnostic of food allergy and should not be performed routinely in adults with rhinitis or isolated GI symptoms 1
• A "positive test result" does not equal having an allergy—in one study, 93% of children avoiding foods based on positive tests were actually tolerant 1

Expert Opinion Is Not Evidence

• Expert opinion should not be used as evidence; the actual observations or experience underlying opinions must be identified and appraised systematically 5

Critical Pitfalls to Avoid

• Do not confuse lack of evidence with evidence of no effect—absence of a clear diagnosis does not mean symptoms are "just food-related" 5
• Avoid unnecessary dietary restrictions without confirmed diagnosis, as this can lead to nutritional deficiencies and reduced quality of life 1
• Do not assume stress is diagnostic—while 60% of IBS patients believe stress aggravates symptoms, this is also true for 40% of patients with organic disease 2
• Physicians often exhibit "action bias" when faced with unexplained symptoms, preferring testing over watchful waiting even when uncertain 6

Recommended Diagnostic Approach

1. Rule out opioid use as a cause of chronic GI symptoms, as these medications should be avoided for chronic pain 1
2. Consider earlier celiac testing with serological markers if you have multiple GI symptoms 1
3. Evaluate for POTS if symptoms worsen with standing, after meals, or include autonomic features 1
4. Check thyroid function (TSH, free T4) if constitutional symptoms are present 4
5. Assess for history of prior infection (including COVID-19), which may prompt consideration for POTS/MCAS given associations with post-infectious GI dysmotility 1
6. Consider breath testing for lactose/fructose intolerance or SIBO only if clinically indicated 1
7. Perform colonoscopy if you have persistent diarrhea, are over 45 years old, or have family history of colon cancer 1