Crohn’s Disease — NZ Condition Guide | KiwiMeds

What is Crohn’s Disease?

Crohn’s disease is a type of inflammatory bowel disease (IBD) — a chronic condition causing inflammation of the digestive tract. Unlike ulcerative colitis (which only affects the colon), Crohn’s disease can affect any part of the digestive tract from the mouth to the anus, and the inflammation goes through the full thickness of the bowel wall. Crohn’s disease affects around 14,000–20,000 New Zealanders and rates are increasing. NZ has one of the highest rates of IBD in the world.

Symptoms

Crohn’s disease symptoms vary depending on which part of the gut is affected and the severity of inflammation. Common symptoms include abdominal pain and cramping (often in the lower right abdomen), diarrhoea (sometimes with blood), fatigue, weight loss, reduced appetite, fever, and mouth sores. Complications can include bowel obstruction, fistulas (abnormal connections between the bowel and other structures), abscesses, and malnutrition. Crohn’s disease can also affect other parts of the body — causing joint pain, eye inflammation, and skin problems.

Causes and Risk Factors

The exact cause of Crohn’s disease is unknown, but it involves an abnormal immune response to gut bacteria in genetically susceptible people. Risk factors include family history (having a first-degree relative with IBD increases risk significantly), being of Ashkenazi Jewish descent, smoking (smoking worsens Crohn’s and increases flare risk), previous gut infections, and possibly a Western high-fat, low-fibre diet. Stress does not cause Crohn’s but can trigger flares.

Diagnosis

Crohn’s disease is diagnosed with a combination of blood tests (inflammation markers, anaemia), stool tests (faecal calprotectin), and endoscopy with biopsy — usually colonoscopy and/or gastroscopy. CT or MRI imaging may be used to assess the extent of disease. Diagnosis can take time because symptoms overlap with other conditions including IBS.

Treatment in New Zealand

Crohn’s disease treatment aims to achieve and maintain remission (no active inflammation). Medicines include aminosalicylates (mesalazine), corticosteroids for flares (prednisone), immunosuppressants (azathioprine, methotrexate), and biologic therapies (infliximab, adalimumab, vedolizumab, ustekinumab). Several biologics are now Pharmac-funded for people with moderate to severe Crohn’s disease. Surgery may be needed for complications. Dietary management (low-residue diet during flares, supplemental nutrition) plays a supportive role.

NZ-Specific Information

Crohn’s and Colitis New Zealand (ccnz.org.nz) is the peak patient organisation providing information, support, and advocacy. Pharmac funds multiple biologic medicines for eligible Crohn’s disease patients. Specialist gastroenterology care is essential — most people with Crohn’s are managed jointly by their GP and a gastroenterologist. The NZ Gastroenterology Society provides treatment guidelines.

Frequently Asked Questions

Is Crohn’s disease curable? There is no cure, but many people achieve long periods of remission with treatment. Will I need surgery? Around 60–70% of people with Crohn’s disease will need surgery at some point, but this does not mean the disease is cured — it often recurs after surgery. Is Crohn’s disease related to bowel cancer risk? Long-standing Crohn’s colitis does increase colorectal cancer risk — regular surveillance colonoscopy is recommended.

Supplements That May Support Management

⚠️ Important: The supplements listed below have varying levels of clinical evidence. They are not a substitute for prescribed medications and should only be considered as adjunctive support under the guidance of a qualified healthcare professional. Always inform your GP or pharmacist before commencing any supplement, as interactions with prescribed medicines are possible.

• Vitamin D — Vitamin D deficiency is highly prevalent in Crohn’s disease due to malabsorption, dietary restriction, and inflammation-mediated bone loss. Supplementation is essential for most patients with Crohn’s, with doses often higher than standard (2000–4000 IU/day) due to malabsorption. Regular monitoring of 25-OH-D levels guides dosing.
• Iron — Iron deficiency anaemia affects 60–80% of IBD patients, either through blood loss in the bowel or reduced absorption. Oral iron may not be tolerated (worsening GI symptoms) — intravenous iron infusion is often preferable and may be arranged through your gastroenterologist.
• B12 (if terminal ileum affected) — The terminal ileum, commonly affected in Crohn’s disease, is the exclusive absorption site for vitamin B12. Resection or severe ileitis necessitates B12 supplementation — typically as 3-monthly intramuscular B12 injections (available through your GP).
• Zinc — Zinc deficiency is very common in active Crohn’s disease due to malabsorption and intestinal losses. Supplementation at 15–30 mg/day supports intestinal mucosal healing and immune function.
• Calcium and Vitamin D — Long-term corticosteroid use and malabsorption significantly increase osteoporosis risk in Crohn’s. Adequate calcium and vitamin D are essential to minimise steroid-related bone loss.

Relevant Vaccinations

Individuals living with Crohn’s disease may benefit from the following vaccinations. Please discuss your vaccination status with your GP or practice nurse, as eligibility and funding through the New Zealand National Immunisation Schedule may apply.

• Influenza (annual) — People with Crohn’s on immunosuppressive therapy (azathioprine, methotrexate, biologics) are at increased infection risk. Annual influenza vaccination is strongly recommended.
• Pneumococcal — Immunosuppression in Crohn’s significantly increases pneumococcal infection risk. Vaccination should ideally occur before commencing immunosuppressive therapy.
• Hepatitis B — Recommended for non-immune patients before commencing biologic therapy, as biologics can reactivate latent hepatitis B.
• CAUTION: Live vaccines are contraindicated on immunosuppressive therapy — Live attenuated vaccines (MMR, varicella, yellow fever, oral typhoid, intranasal influenza) are contraindicated in people on biologic therapies or significant immunosuppression. Discuss all vaccination with your gastroenterologist.
• COVID-19 — People with Crohn’s on immunosuppressive therapy are at increased COVID-19 risk. Maintaining vaccination and booster doses is strongly recommended.

Dietary Guidance

Evidence-based dietary modifications play a meaningful role in the management of Crohn’s disease. The following foods are generally recommended as part of a balanced, condition-appropriate diet. A referral to a registered dietitian may be beneficial for personalised nutritional planning.

• Exclusive enteral nutrition (EEN) — during flare — Liquid elemental or polymeric formula nutrition is a highly effective treatment for Crohn’s disease activity, particularly in children and adolescents, achieving remission in 80% of cases without steroids. It is used as primary induction therapy under medical supervision.
• Low-residue diet during flares — A low-fibre, low-residue diet reduces intestinal transit and mechanical irritation during active disease flares. Well-cooked vegetables, refined grains, and lean proteins are generally better tolerated.
• High-protein foods for mucosal repair and muscle maintenance — Protein requirements are elevated in active Crohn’s (1.2–1.5 g/kg/day). Adequate intake supports intestinal mucosal regeneration and prevents malnutrition-related complications.
• Identify personal trigger foods — Common triggers in Crohn’s include raw vegetables, high-fibre foods, spicy foods, caffeine, and alcohol. Keeping a food diary identifies individual patterns. An IBD dietitian can help distinguish disease activity from food intolerance.
• Limit: ultra-processed foods, emulsifiers — Dietary emulsifiers (polysorbate 80, carboxymethylcellulose — found in processed foods) disrupt the intestinal mucus barrier and are associated with increased IBD activity in both animal models and human epidemiological studies.

Related Conditions & Medications

Related medications: Azathioprine, Prednisone. Related conditions: IBS.