Review: evidence is lacking on the effectiveness of dietary advice in illness-related malnutrition
Ms C Baldwin, King’s College London, London, UK;
Is dietary advice to improve nutritional intake effective in adults with illness-related malnutrition?
Studies selected compared dietary advice (instruction in modification of food intake given by a dietician or other healthcare professional with the aim of improving nutritional intake) with no advice or prescription of an oral nutritional supplement (with or without dietary advice) in adults (>16 y of age) with chronic illness or at nutritional risk who have suboptimal nutritional status. Studies involving pregnant women, people with eating disorders, conditions of food shortage, or use of elemental supplements were excluded. Outcomes were mortality, hospital admission, and weight gain.
Cochrane Cystic Fibrosis and Genetic Disorders Group trials register (Sep 2007); Cochrane Central Register of Controlled Trials (Issue 2, 2005); Medline, EMBASE/Excerpta Medica, CINAHL, CancerLit, and AMED (to Nov 2005); electronic searches done by the National Collaborating Centre for Acute Care; and reference lists were searched for randomised or quasi-randomised controlled trials. Experts and manufacturers of nutritional supplements were consulted. 36 trials (n = 2714, mean age 23–85 y, 0–100% men) met the selection criteria: advice was compared with no advice in 8 trials, with supplements in 5 trials, and with advice plus supplements in 13 trials; advice plus supplements (if required) was compared with no advice in 12 trials. 23 trials reported an acceptable method of randomisation, 19 had adequate allocation concealment, and 1 reported blinding of the outcome assessor.
No trial showed any difference in mortality between groups for any of the 4 comparisons. Advice compared with no advice (2 trials, n = 137 and 57) and advice compared with supplements (1 trial, n = 50) did not differ for hospital admission. Advice promoted weight gain more than no advice, but interventions involving nutritional supplements promoted weight gain more than advice or no advice (table).
There is insufficient evidence to draw meaningful conclusions about the effectiveness of dietary advice to improve nutritional intake in adults with illness-related malnutrition.
Baldwin C, Weekes C. Dietary advice for illness-related malnutrition in adults. Cochrane Database Syst Rev 2008;(1):CD002008.
Clinical impact ratings: Elderly care 6/7; Family/general practice 5/7; General/internal medicine 5/7; General surgery 5/7; Infectious disease 6/7; Oncology 6/7; Respirology 6/7
Provision of dietary advice is a core dietetic competency, but its effectiveness in increasing nutrient intake and body weight is unknown. In addition, there are firmly held, but unsubstantiated, ideas about the desirability of improving nutritional intake using ordinary foods before resorting to oral supplements. It may be possible to increase oral nutritional intake in various ways. The review by Baldwin and Weekes is a step toward clarifying the effectiveness of dietary advice and nutritional supplements in treating illness-related malnutrition.
“Dietary advice” is not a standardised intervention, so it is unclear whether each study evaluated the same treatment. The studies varied in terms of inclusion criteria used to define malnutrition. Patients in the studies in the review were not homogenous, and a broad range of diseases and related treatments were included. Duration of follow-up varied widely. In studies that could be combined by meta-analysis, the results for many outcome measures had statistically significant heterogeneity.
It remains appropriate practice for nurses in acute care facilities, residential care units, and community and primary healthcare settings to refer people with illness-related malnutrition for dietary advice because the findings of this review may reflect a lack of good quality evidence, rather than a lack of effectiveness.
To determine the effectiveness of different interventions in increasing dietary intake in people with illness-related malnutrition, the priority is for research in the form of large, adequately-powered, randomised controlled trials with sufficiently long follow-up.