Does protein and energy supplementation benefit elderly people at risk of malnutrition?

Keywords Dietary supplements, Energy intake, Protein intake, Elderly people, Malnutrition

• This article has been double-blind peer reviewed

Review question

What is the best available evidence regarding the benefits of giving oral nutritional supplements to elderly people who are at risk from malnutrition?

Nursing implications

Malnutrition is a major cause for concern in elderly people, whether they are hospitalised or live in the community. The problem is relevant to nurses because the consequences of sub-optimal nutrition impairs the individual’s immune response, muscle function, respiratory function, wound healing, rehabilitation, mental status and general well-being. Nutritional supplements containing protein and energy are frequently prescribed, however detailed information to inform practice is lacking.  

Study characteristics

The review examined 62 randomised and quasi-randomised controlled trials of protein and energy oral supplements involving 10,187 people. Study groups had a minimum average age of 65 years. Groups that were recovering from cancer treatment or were in critical care were excluded.

Studies originated from Europe, USA, Canada, Australia and Hong Kong and included patient groups hospitalised for acute conditions (26 studies), long-stay or care of the elderly wards, or continuing care wards or nursing homes (15 studies) or living at home (21 studies).

The quality rating was poor for the majority of included studies because of the lack of blinding of participants and treatment providers; inadequate sample sizes and inadequate reporting of numbers of participants who were allocated, assessed, lost to follow-up or did not take the supplements. There was also bias due to selective reporting of outcomes, such as mortality.

Measurable outcomes for supplementation interventions included mortality, morbidity (for example, pressure sores, deep vein thrombosis, infections), functional status (such as walking distance, number of falls), weight changes and arm muscle circumference. Other measurable outcomes were: compliance with the intervention, length of hospital stay, frequency of primary care contact, adverse effects and quality of life. 

Interventions aimed to provide dietary oral supplements, consisting of commercial sip feeds, milk based formulations or direct fortification of food by the addition of calories and protein. Some interventions included minerals and vitamins.

Control groups were asked to maintain usual dietary regimes or were provided with a diluted, lower calorie supplement. It was noted that 10 trials mentioned the inclusion of dietary advice in their intervention but few trials considered altering the nutrient density or diversity of the diet.

Intervention time ranged from 10 days to 18 months, but realistically was not long enough in most cases to detect outcome differences in functional status, quality of life or mortality. Meta-analysis was undertaken where possible.

Summary of main evidence

The meta-analysis indicated a small, but consistent benefit from protein and energy oral supplementation demonstrated by an increase in the pooled weighted mean difference for the percentage of weight change in 42 studies of 2.2% (95% Confidence Intervals [CI] 1.8 to 2.5). However, details in the percentage of change in fat and muscle were not provided in studies.

The subgroup analysis showed a near statistically significant decrease in mortality in undernourished groups who received 400 kcal or more per day (N= 2461, RR 0.79, 95% CI 0.64 to 0.97) but not in all older populations.

The number of complications such as infection, deep vein thrombosis and pressure sores was significantly reduced based on the meta-analysis of 24 trials (N=6225) in intervention groups when compared against controls (RR 0.86, 95% CI 0.75 to 0.99). Subgroup analysis by diagnostic groups indicated fewer complications  for patients with hip fractures (N= 298 RR 0.60, 95% CI 0.40 to 0.91) and for patients following stroke (N= 4063 RR 0.65, 95% CI 0.40 to 1.03).

Adverse effects such as nausea and diarrhoea were recorded in 18 trials but none were statistically significant.

AUTHOR Marilyn N. Kirshbaum, RN (US), RGN (UK), BSc, MSc, PhD, DipAdultOnc, is a reader in nursing, University of Huddersfield, School of Health and Human Sciences, Huddersfield, West Yorkshire, and a member of the Cochrane Nursing Care Field

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