Zinc

Why it happens in Crohn’s disease

Zinc is absorbed in the jejunum and proximal ileum, both frequently involved in Crohn’s disease. Losses are then amplified by diarrhoea: intestinal secretions are zinc-rich, so high stool output, fistula output or a high-output stoma drains zinc rapidly. Inflammation adds a third mechanism — cytokines induce metallothionein, which sequesters zinc in the liver and lowers circulating levels independently of total body stores. Because zinc is a cofactor for over 300 enzymes including those governing epithelial repair and tight-junction assembly, deficiency and impaired mucosal healing reinforce one another.

Who is most at risk

• High-output diarrhoea, enterocutaneous fistula or high-output stoma
• Extensive jejunal or proximal small bowel disease
• Active inflammation with hypoalbuminaemia
• Protracted low oral intake or exclusive liquid diets
• Chronic alcohol use

Symptoms of deficiency

• Impaired wound healing, including slow healing of perianal disease and surgical sites
• Loss of taste and smell, contributing to poor appetite
• Hair loss, brittle nails with white transverse lines
• Dermatitis, classically around the mouth, eyes and perineum
• Recurrent infections and impaired T cell function
• Night blindness (zinc is required for retinol-binding protein) and, in adolescents, delayed growth

Many of these overlap with Crohn’s disease itself, which is exactly why deficiencies are missed. Fatigue attributed to active disease is frequently anaemia, and neuropathy attributed to medication is sometimes B12.

How it is tested

Serum or plasma zinc is the practical test but falls during inflammation and hypoalbuminaemia, so interpret it alongside CRP and albumin — a normal zinc in an inflamed, hypoalbuminaemic patient may still conceal deficiency. Collect the sample fasting and avoid haemolysis, which falsely elevates the result. Zinc deficiency in IBD is associated with substantially higher rates of hospitalisation (48.0% vs 17.7%), surgery (19.6% vs 5.8%) and IBD-related complications, which is a strong argument for checking it rather than assuming.

Replenishment protocols

Typical replacement is 20–40 mg/day of elemental zinc for 2–3 months, then retest — this is a nutrient where indefinite high-dose supplementation causes harm. A small Crohn’s study using zinc sulfate 110 mg three times daily for 8 weeks in patients in remission resolved abnormal intestinal permeability, with fewer relapses over the following year; the study was small and unblinded but its mechanism is consistent with zinc’s role in tight-junction biology. Take zinc away from food and separately from iron and calcium, which compete for absorption.

Amounts reflect what gastroenterology literature and guidelines describe. The right dose for you depends on your test results, absorption and surgical history, so test first and work with your care team to personalise it.

Medication interactions

Zinc and copper compete for the same transporter, so zinc above roughly 40 mg/day over months causes copper deficiency, which produces its own anaemia and neuropathy — check copper if supplementing long term. Zinc reduces absorption of quinolone and tetracycline antibiotics, relevant given how often ciprofloxacin and metronidazole are used for perianal Crohn’s. Corticosteroids such as Prednisone increase urinary zinc loss.

Sources

1. 1

   Prevalence of zinc deficiency in inflammatory bowel disease: a systematic review and meta-analysis

   Zupo R, Sila A, Castellana F, et al. · Nutrients · 2022

2. 2

   Zinc deficiency is associated with poor clinical outcomes in patients with inflammatory bowel disease

   Siva S, Rubin DT, Gulotta G, Wroblewski K, Pekow J. · Inflammatory Bowel Diseases · 2017 · PMID 27930412

3. 3

   Zinc supplementation tightens “leaky gut” in Crohn’s disease

   Sturniolo GC, Di Leo V, Ferronato A, D’Odorico A, D’Incà R. · Inflammatory Bowel Diseases · 2001