The Potential Role of Zinc Supplementation on Pressure Injury Healing in Older Adults

A Review of the Literature

Melissa Heintschel, MS, RD, LD; Roschelle Heuberger, PhD, RD

Disclosures

Wounds. 2017;29(2):56-61. 

In This Article

Discussion

The elderly adult population is at risk for compromised skin integrity, inadequate dietary intakes, reduced Zn absorption, and malnutrition. As a result, PI development is a common yet detrimental complication that can lead to poor clinical outcomes. Although Zn deficiency is difficult to diagnose due to lack of sensitive Zn biomarkers, studies[25,26,28] indicate Zn status is likely to be compromised in older adults with PIs. Recognizing these conditions in this target population is vital in initiating nutritional interventions as Zn plays an important role in wound healing for collagen synthesis and improved immune response. The use of both standard and specialty ONS as nutritional interventions should be considered for PI wound healing.

Identifying Nutrient Inadequacies

Both macronutrient and micronutrient oral intakes were found to be suboptimal in the majority of older patients with PIs. Two observational studies[25,28] that measured oral intakes demonstrated food intake alone is inadequate in meeting sufficient nutrient intakes for both caloric targets and Zn intake in older adults with PIs. Raffoul et al[25] found target energy consumption was variable through food intake 76% ± 21%, and the addition of ONS provided 35% ± 12% of energy requirements.[25] Prior to the onset of offering ONS, plasma Zn levels measured a median of 9.4 μmol/L, below the normal range, and improved slightly (P = .07) by day 10 after ONS consumption.[25] These findings suggest ONS acceptance reduces these energy and mineral intake deficits. Similarly, Wojcik et al[26] found that only 59% of subjects met their energy requirements, and 41% met estimated protein needs for wound healing without supplementation.[26] Additionally, intakes of Zn were least likely to meet Estimated Average Requirement compared to other mineral biomarkers measured; 45.5% of subjects had inadequate Zn intake with food alone.[26] Alternatively, only 22.2% of subjects accepting the ONS consumed inadequate Zn levels, indicating a measurable improvement.[26] These improvements in nutrient consumption, including higher protein intakes, were associated with higher BPURAS scores.[26] These findings suggest older adults with PIs are at risk for a number of nutrient deficiencies including Zn, which may impair the wound healing process.

An observational study[27] investigated vitamin and trace element losses from wound exudates and found 0.5 mg Zn loss from open abdominal wounds and 0.3 mg Zn loss from soft-tissue wounds over 24 hours. This loss accounts for 5% and 3% of the RDA for Zn, respectively.[27] While this study did not focus on the older adult population with PIs, it is important to consider because nutrient loss may also occur from wound exudate in PIs. These studies support the aforementioned premise that older adults with PIs are prone to inadequate dietary intakes, as well as nutrient losses from wound exudate, which increases risk for malnutrition, a condition that is associated with increased severity in PIs.[25–27] Though identifying Zn deficiency may be difficult, interventions for PI healing should consider this possible insufficiency in addition to the other known factors.

Effects of Zn in ONS for Treatment of Wounds

Nutritional interventions for PIs are beneficial in order to decrease wound-healing time.[29–34] Heyman et al[29] studied how ONS containing fortification of several nutrients providing additional protein, arginine, vitamins C and E, and Zn, in addition to standard wound care in the aged is supported in use for the reduction in PI area and optimal for wound healing. The use of specialized ONS designed to improve wound healing versus standardized ONS remains controversial. Cereda et al[30] concluded that specialized ONS formula enriched with arginine, Zn, and antioxidants was superior to standard ONS and resulted in a greater reduction in PI area with a mean reduction of 60.9% compared to 45.2%, respectively. Another clinical trial[31] found that ONS enriched with high protein, arginine, Zn, and vitamin C and standard nutrition formula both improve PI healing, but the enriched ONS had higher rates of PI healing as measured by PUSH score and ulcer area (P < .05). It is a preferable formula for wound healing.[31] Serum Zn levels were also monitored.[31] There was a 107.5 μg/dL ± 106.6 μg/dL Zn increase from baseline to week 12 in the treatment group, whereas serum Zn dropped 32.5 μg/dL ± 87.1 μg/dL in the control, suggesting nutritional inadequacies are more efficiently replete with the treatment formula.[31]

In contrast, a study investigating a wound-specific ONS enriched with immune-enhancing nutrients including arginine, Zn, and vitamin C, versus standard high protein ONS found the standard ONS formula was more beneficial in improving PUSH scores and healing (P = .044).[32] At the same time, nutrition status and quality of life remained similar between both groups.[33] These variable findings in the literature should prompt health care clinicians to implement an appropriate plan of care based on individual needs to most effectively treat each patient.

Use of Zn as PLZ

Another avenue for possible nutritional interventions in wound healing is CAR, a dipeptide composed of β-alanine and L-histidine, and PLZ.[33] Because CAR has many biological functions linked to anti-aging activity, it is presumed to have an effect on age-related diseases including wound healing.[35] The first controlled clinical study[33] to investigate ONS for PI treatments in their respective groups, CAR and PLZ, along with a control group receiving no supplementation, resulted in significant improvements in PUSH scores in both treated groups (P = .02 vs. control; P = .009 vs. control, respectively). The PLZ treatment group experienced increases in serum Zn levels (P < .001), though serum copper had decreased (P < .001).[33] These findings suggest both CAR and PLZ may be potential treatments for PIs. Future research should involve larger sample sizes with randomized trial methods and special consideration to appropriate length of PLZ treatment in order to ensure safe dosing regimens.

Use of Zn Alone for Wound Healing

Due to its notable role in immunity and wound healing, clinical trials testing the effects of Zn sulfate as an oral supplement date back to the 1960s.[36] However, the study by Houston et al[34] where they used oral Zn as the sole intervention shows it is much less frequent, likely as a result of disappointing findings. Moreover, older patients receiving high doses of Zn sulfate (440 mg) experienced adverse effects attributed to the supplementation including infection, which required more treatment for antibiotic therapy and nausea/vomiting.[34] Recent studies have shown more promising results with wound healing by incorporating a variety of nutrients through ONS.

Cost-effectiveness in Treatment

Another consideration to clinical care is cost-effective treatments. A clinical trial[37] completed a cost analysis on the difference in medical costs of PI care and cost effectiveness of a disease-specific nutritional formula enriched with arginine Zn and antioxidants versus a standard formula. Both groups had improved wound healing, though the experimental group had greater improvements in the reduction in PI area (P = .012). The specialty formula cost significantly more (P < .001), but the patients receiving this formula had reduced costs in non-nutritional wound care management of PIs (P = .001). This care included dressing materials, pressure-relieving mattresses, nursing expenses, and antibiotics.[37] As a result, the use of a specialized formula should not be discounted based on initial higher cost.

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