Antioxidant micronutrients for lung disease in cystic fibrosis.Cochrane Database Syst Rev 2010; (12):CD007020CD
Airway infection leads to progressive damage of the lungs in cystic fibrosis (CF), partly due to oxidative stress. Supplementation of antioxidant micronutrients (vitamin E, vitamin C, β-carotene and selenium) may help maintain an oxidant-antioxidant balance. Current literature suggests a relationship between oxidative status and lung function.
To synthesize existing knowledge of the effect of vitamin C, vitamin E, β-carotene and selenium in CF lung disease.
The Cochrane CF and Genetic Disorders Group CF Trials Register, PubMed, CINAHL and AMED were searched using detailed search strategies. We contacted authors of included studies and checked reference lists of these studies for additional, potentially relevant studies.Last search of CF Trials Register: 09 September 2010.
Randomized controlled trials and quasi-randomized controlled trials of people with CF with explicitly stated diagnostic criteria, comparing vitamin E, vitamin C, β-carotene and selenium (individually or in combination) to placebo or standard care.
DATA COLLECTION AND ANALYSIS
Two authors independently selected trials, extracted data and assessed risk of bias. We contacted trialists to obtain missing information. Primary outcomes are lung function and quality of life; secondary outcomes are oxidative stress, inflammation, body mass index, days on antibiotics and adverse events during supplementation. If meta-analysed, studies were subgrouped according to combined or single antioxidant supplementation.
Four randomized controlled trials and one quasi-randomized controlled trial were included; only three trials (87 participants) presented data suitable for analysis. Based on two trials, there was no significant improvement in lung function; one trial indicated significant improvement in quality of life favouring control, mean difference -0.06 points on the quality of well-being scale (95% confidence interval -0.12 to -0.01). Based on two trials, selenium-dependent glutathione peroxidase enzyme significantly improved in favour of combined supplementation, mean difference 1.60 units per gram of haemoglobin (95% CI 0.30 to 2.90) and selenium supplementation, mean difference 10.20 units per gram of haemoglobin (95% CI 2.22 to 18.18). All plasma antioxidant levels, except vitamin C, significantly improved with supplementation.