A Cochrane review included 23 studies.
There is evidence from one trial that mixed nutritional supplements reduces the chance of developing a pressure ulcer for elderly critically ill patients within two to three weeks. 672 people of >65 years, in the acute phase of a critical illness, followed up for 15 days or until discharge. At 15 days, the cumulative incidence of pressure ulcers (all grades) was 40% (118/295) in the nutritional intervention group versus 48% (181/377) in the control group. This equates to a relative risk of developing a sore with the supplement of 0.83 (95% CI 0.70 to 0.99). In three small trials of mixed supplements for people recovering from hip fractures there were smaller numbers of ulcers in the supplement group but the trials were far too small to determine whether these differences were due to chance or a true effect.Eleven trials compared a combination of nutritional supplements, consisting of a minimum of energy and protein in different dosages, for the prevention of pressure ulcers. A meta-analysis of eight trials (6062 participants) that compared the effects of mixed nutritional supplements with standard hospital diet found no clear evidence of an effect of supplementation on pressure ulcer development (pooled RR 0.86; 95% CI 0.73 to 1.00). Fourteen trials evaluated the effects of nutritional supplements on the healing of existing pressure ulcers: seven trials examined mixed nutritional supplements, three the effects of proteins, two trials examined zinc, and two studies examined ascorbic acid. The included trials were heterogeneous with regard to participants, interventions, comparisons and outcomes and meta-analysis was not appropriate. There was no clear evidence of an improvement in pressure ulcer healing from the nutritional supplements evaluated in any of these individual studies.
Comment: The quality of evidence is downgraded by study quality (inadequate or unclear allocation concealment) and by imprecise results (few patients and wide confidence intervals).