The disease is characterised by intermittent acute episodes of worsening asthma, often called asthma ‘attacks’. Prevention of asthma attacks is a key goal of asthma management, as they pose the greatest risk, cause the most anxiety to patients and their families and generate the greatest cost to the health care system.
Children aged <14 years have the highest rate of hospital emergency department visits and hospitalisations due to asthma attacks. In children, respiratory virus infections (such as the common cold virus), trigger >80% of acute asthma attacks. Inhaled corticosteroids are the most effective therapy for controlling asthma day to day, however, they do not prevent acute attacks of asthma due to virus infection and are associated with unwanted side effects. Moreover, these repeat viral infections and asthma attacks are associated with a greater risk of poor lung function in adulthood. Therefore, alternative prevention strategies to reduce the risk of asthma attacks in children are urgently needed.
Children with asthma have lower blood levels of antioxidants than the general population and this has been linked to more severe asthma and more frequent viral infections and attacks. Thus, a solution may be to increase the intake of high-antioxidant foods, particularly fruit and vegetables (F&V). We have recently shown that a high F&V diet reduces the risk of asthma attacks in adults. In a 14 week randomised controlled trial (RCT), adults with asthma consumed either a high F&V diet or a low F&V diet. Asthmatic adults consuming the low F&V diet were 2.26 times more likely to have an asthma attack than subjects consuming the high F&V diet. While this is an extremely important and promising observation in adults, the results cannot be extrapolated to children. Thus, a rigorously designed RCT in children is required.
Aim: To examine whether consumption of a high fruit and vegetable diet can reduce the risk of viral- induced asthma attacks in children with asthma.
Study Design: This is a 6-month RCT in asthmatic children who have a history of frequent asthma attacks. Subjects will be randomised to a high F&V diet (≥7 F&V serves/day) or a control diet (≤3 F&V serves/day). All subjects will be provided with food hampers containing the foods they will be required to eat, matched for energy and macronutrient composition, but different in content of phytonutrients, such as antioxidants and soluble fibre. The primary outcome will be the time to the first asthma attack (requiring oral corticosteroids). We will also detect the presence of viruses via nasal swabs. Samples will be collected for measurement of airway and systemic inflammation and to examine epigenetic mechanisms, once additional funding becomes available. Based on our previous study, we need 46 subjects to complete this RCT. We aim to recruit 20 subjects in 2015, in order to demonstrate feasibility of the intervention in children and to collect pilot data for an NHMRC grant submission in 2016.