Abstract:

Background
People with cystic fibrosis and pancreatic insufficiency are at risk of fat soluble vitamin deficiency as these vitamins (A, D, E and K) are co-absorbed with fat. Thus, some cystic fibrosis centres routinely administer these vitamins as supplements but the centres vary in their approach of addressing the possible development of deficiencies in these vitamins. Vitamin A deficiency causes predominantly eye and skin problems while supplementation of vitamin A to excessive levels may cause harm to the respiratory and skeletal systems in children. Thus a systematic review on vitamin A supplementation in people with cystic fibrosis would help guide clinical practice.

Objectives
To determine if vitamin A supplementation in children and adults with CF:
1. reduces the frequency of vitamin A deficiency disorders;
2. improves general and respiratory health;
3. increases the frequency of vitamin A toxicity.

Search strategy
We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises of references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.

Date of the most recent search of the Group's Cystic Fibrosis Trials Register: 26 November 2009.

Selection criteria
All randomised or quasi-randomised controlled trials comparing all preparations of oral vitamin A used as a supplement compared to either no supplementation (or placebo) at any dose and for any duration, in children or adults with cystic fibrosis (defined by sweat tests or genetic testing) with and without pancreatic insufficiency.

Data collection and analysis
No relevant studies for inclusion were identified in the search.

Main results
No studies were included in this review.

Authors' conclusions
As there were no randomised or quasi-randomised controlled trials identified, we cannot draw any conclusions on the benefits (or otherwise) of regular administration of vitamin A in people with cystic fibrosis. Until further data are available, country or region specific guidelines on the use of vitamin A in people with cystic fibrosis should be followed.