Salicylate diet claims “unconvincing”

AUSTRALIAN immunologists have questioned the use of salicylate elimination diets for children, with a group of paediatric immunologists writing in the MJA that the diets are not supported by evidence and may be harmful. (1) In a literature review and a retrospective review of case notes from the authors’ own practices looking at children who had been on a low salicylate diet, the authors said they could find no peer-reviewed evidence supporting the use of the diet in conditions for which it is prescribed, such as eczema and behavioural disturbances. They also identified 31 adverse events from the case notes — from failure to thrive (13 cases) and food aversion (six cases) to eating disorders (four cases) and alopecia (two cases) — in the 66 children for whom this information was available. “The use of low salicylate diets in children is not supported by current evidence or by expert opinion”, wrote Dr Paul Gray, of the department of immunology and infectious diseases at Sydney Children’s Hospital, and his coauthors. “While our retrospective case note review is insufficient to prove any risk associated with the diets, it is concerning that harm may occur when children and adolescents are placed on such restrictive diets, particularly if they stay on them for long periods.” However, in a commentary accompanying the research, Professor Robert Loblay, of the department of clinical immunology at Sydney’s Royal Prince Alfred Hospital, and coauthors said that “with suitable guidance” salicylate elimination diets based on n-of-1 testing were safe and could improve quality of life. (2) “The results from peer-reviewed publication of group data may not be transferrable to determine what dietary modifications are appropriate in individual cases; the diagnostic elimination–challenge process we use is essentially a single-patient (n-of-1) trial method which is generally considered to provide strong evidence in guiding clinical practice”, the authors wrote, adding that intake of nutrients by children on a low chemical diet was usually at or about the recommended daily amount. Professor Geoff Cleghorn, professor of paediatrics at the University of Queensland, told MJA InSight that while the literature review had found no evidence of benefit from low salicylate diets, the researchers had drawn a long bow in linking the diets to harm. “The authors’ analysis would suggest that the children who were on a low salicylate diet did suffer from adverse events, but whether this was because of the low salicylate per se, or because of other things that were being promulgated with the diet, it’s impossible to tell from their evidence”, Professor Cleghorn said. “It’s very unlikely that low salicylate diets are done in isolation, they are done with a whole bunch of other food removals.” While Professor Cleghorn said he was unconvinced that the salicylate elimination diet was harmful, he was equally uncertain of any benefit. He said the commentary did not add to the evidence, presenting only anecdotal reports of benefit. “I’m not sure that I’m convinced that [a low salicylate diet is] hazardous … But equally, does one need to do it?” he said. “Few things we do come without risk.” Dr Christine Ziegler, paediatric allergist/clinical immunologist at Flinders Medical Centre, said there had been a “massive surge” in IgE and non-IgE mediated food allergies to key foods including egg, dairy, wheat and soy in infants and young children. She said it was these common foods that most often needed to be targeted with dietary modification. However, food chemical intolerances, including salicylate intolerances, occurred very infrequently in children aged under 10 years, Dr Ziegler told MJA InSight. “We don’t tend to use [salicylate elimination] diets, because the kids are presenting with actual food allergies, as opposed to food chemical intolerance”, she said. Salicylates and other food chemicals were seen across a wide range of different foods. “If salicylates are targeted with dietary elimination, it can cut out a wide range of foods from the diet unnecessarily and can contribute to restricted nutritional range”, Dr Ziegler said. In a research paper published in the same issue of the MJA, researchers found that parents of children with food allergies were often complacent about precautionary labelling on food, regardless of whether their children had a history of anaphylaxis. (3) The researchers concluded that the use of fewer precautionary statements and more effective labelling strategies may lead to less consumer complacency.  

1. MJA 2013; 198: 600-602 2. MJA 2013; 198: 603 3. MJA 2013; 198: 621-623