Dysphagia Knowledge Hub — 吞嚥困難知識庫

Zinc Supplementation for Pressure Ulcers in Dysphagia Patients

Pressure ulcers (pressure injuries) represent a major complication of immobility, malnutrition, and compromised skin integrity in patients with dysphagia — particularly elderly individuals in long-term care who are bed-bound or wheelchair-dependent. Adequate nutritional support, including optimal micronutrient status, is an established pillar of wound healing and pressure ulcer prevention. Zinc, a trace element essential for multiple wound healing pathways, is frequently deficient in tube-fed dysphagia patients and represents a specific, correctable nutritional gap. This article reviews the mechanism of zinc’s role in wound healing, the epidemiology of zinc deficiency in this population, evidence-based supplementation protocols, IDDSI-compatible zinc-rich food sources, the critical zinc-copper interaction, and alignment with EPUAP/NPUAP pressure ulcer guidelines.

Zinc’s Role in Wound Healing

Zinc participates in wound healing through at least four distinct mechanisms:

1. Collagen synthesis: Zinc is a cofactor for prolyl hydroxylase and lysyl oxidase, the enzymes responsible for cross-linking collagen fibres in the extracellular matrix. Collagen is the primary structural protein in wound repair; without adequate zinc, collagen deposition and tensile strength development are impaired. Animal studies of zinc deficiency demonstrate markedly reduced wound breaking strength and delayed epithelialisation (Lansdown et al., 2007).

2. Cell proliferation and DNA synthesis: Zinc-finger proteins are transcription factors regulating cell cycle progression. Zinc deficiency directly impairs fibroblast, keratinocyte, and immune cell proliferation — all of which are required for granulation tissue formation and re-epithelialisation.

3. Immune function: Zinc maintains the integrity of neutrophil and macrophage function; deficiency impairs phagocytosis and oxidative burst activity, reducing clearance of wound biofilm and increasing infection risk.

4. Antioxidant protection: Zinc is a component of superoxide dismutase (Cu-Zn SOD), protecting wound tissue from oxidative damage. In inflamed wound beds, local reactive oxygen species generation is high; zinc depletion worsens oxidative tissue injury.

In summary, zinc deficiency impairs all four major phases of wound healing (haemostasis, inflammation, proliferation, and remodelling) and has been associated in clinical studies with prolonged wound healing time, reduced granulation tissue quality, and increased wound infection rates.

Deficiency in Tube-Fed Patients

Zinc deficiency is common in hospitalised and institutionalised patients with dysphagia:

Supplementation Dose: 25–50 mg Elemental Zinc

For dysphagia patients with active pressure ulcers, the EPUAP/NPUAP/PPPIA Clinical Practice Guidelines (European Pressure Ulcer Advisory Panel, 2019) recommend:

Zinc supplementation: 25–50 mg elemental zinc per day for patients with non-healing pressure ulcers and confirmed or suspected zinc deficiency. This is above the RDA (8–11 mg/day) but below the established tolerable upper intake level (UL) of 40 mg/day for routine intake; therapeutic wound-healing doses of 25–50 mg elemental zinc are used for limited durations (typically 4–12 weeks).

Commercially available supplementation forms in HK:

Zinc supplementation should ideally be taken with food to reduce gastric irritation. For tube-fed patients, crush tablets into fine powder and flush with water before and after administration.

Zinc-Rich IDDSI-Compliant Foods

Patients with partial oral intake can supplement zinc through dietary sources at appropriate IDDSI texture levels. Zinc-rich foods that can be texture-modified to IDDSI Level 4–6:

IDDSI Level 4 (Pureed):

IDDSI Level 5 (Minced and Moist):

IDDSI Level 6 (Soft and Bite-Sized):

In dietary practice, a dysphagia patient who achieves 100 g of texture-modified red meat per meal across two to three meals per day will obtain approximately 10–15 mg zinc daily from food — approaching but typically not meeting therapeutic wound-healing targets without additional supplementation.

Zinc-Copper Interaction

High-dose zinc supplementation competitively inhibits intestinal copper absorption via metallothionein induction in enterocytes. Sustained zinc intake above approximately 25–40 mg/day depletes serum copper, potentially producing:

Clinical guidance: When prescribing therapeutic zinc (25–50 mg/day) for more than four weeks, co-supplement with 2 mg elemental copper daily to prevent deficiency. Serum copper (or caeruloplasmin) should be monitored alongside zinc at baseline and after four to six weeks of supplementation. Patients already receiving formula-based tube feeding may be receiving baseline copper from the formula; check formula composition before prescribing additional copper.

The zinc-to-copper ratio in supplementation should not exceed 15:1 (copper intake mg × 15 ≥ zinc intake mg) for safety during prolonged use.

EPUAP/NPUAP Guidelines Summary

The 2019 European Pressure Ulcer Advisory Panel / National Pressure Injury Advisory Panel joint guidelines state:

In HK, EPUAP guidelines are referenced by the Hospital Authority’s wound care protocols and Tissue Viability Nursing Services.

References