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G450(P) ‘a gargle a day keeps the bugs away’: can pineapple juice prevent upper respiratory tract infections keeping paediatricians healthy in winter
  1. GM Woods,
  2. EC Russell-Jones
  1. Paediatrics, Croydon University Hospital, Croydon, UK


Introduction Bromelain is a protease enzyme, only found in pineapples. Exhibiting extraordinary mucolytic effect when directly applied to mucus plugs, it may have a role in preventing upper respiratory tract infections (URTIs).

In our paediatric team of 18, all except 2 had one or more URTIs last year, 4 taking time off work for URTIs. Working feeling unwell, or taking time off, are ‘at risk’ situations; spreading viruses to vulnerable patients and often causing difficult ‘gaps’ in rotas.

Aim To assess the effectiveness of ‘Bromelain’, as an active ingredient in pineapple juice, in producing mucolytic effect.


  1. An experiment applying Bromelain in solution to mucus plugs on petri–dishes.

  2. After gaining verbal consent, a small blinded study was done randomising 18 paediatric doctors to gargle with fresh pineapple juice, or a ‘yellow coloured drink’ not containing pineapple. None had known allergy to pineapple or were taking aspirin/warfarin. They were asked to gargle, swallow, and then spit out any sputum into a sterile pot. The researcher, blinded to randomisation, macroscopically examined the sputum for mucus content. 15 people participated, 3 declined.


  1. Bromelain solution exhibited a powerful mucolytic effect when directly applied to mucus plugs.

  2. 14 of 15 samples examined by the blinded researcher (93.3%) were correctly categorised into the appropriate group due to the presence of mucus plugs found only in the pineapple juice group. Those who had not had breakfast prior to the gargling experiment were also correctly identified. A significant larger quantity of mucus was present in these samples.

Conclusion Pineapple Juice seems to encourage production of mucus plugs, so with their removal may have a role in reducing the number of URTIs. One proposed mechanism is the proteolytic properties of Bromelain, within the Pineapple juice, causing non-adhesion of viruses to the oropharyngeal mucosa, so preventing entrance into cells to replicate. The body may thus not succumb to the virus with reduced viral load present. For bacteria, it may breakdown the peptidoglycan wall.

It is proposed to test this theory, with a double blinded RCT using Bromelain solution.

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