Vitamin E supplementation in people with cystic fibrosis.

The Cochrane database of systematic reviews

Mar 2017

DOI: 10.1002/14651858.CD009422.pub3

Citations:10

Influential Citations:0

Systematic Reviews / Meta-Analyses

Enhanced Details

Methods

Four randomized controlled trials with a total of 141 participants were included. The participants varied in age, with some studies specifying children aged six months to 14.5 years. Outcomes primarily measured serum vitamin E levels, alongside other parameters like weight and muscle power.

Intervention

Vitamin E supplementation was assessed in four studies involving individuals with cystic fibrosis over durations ranging from 10 days to six months. Various formulations (water-miscible and fat-soluble) were compared to control groups with no supplementation.

Results

Vitamin E supplementation significantly improved serum vitamin E levels in individuals with cystic fibrosis. However, no data were available regarding the primary outcomes related to vitamin E deficiency disorders, lung function, or quality of life. The implication is that while supplementation may enhance vitamin E levels, its broader health impacts remain uncertain.

Limitations

The studies had variations in methods and formulations, which limited the generalizability of the findings. Risks of bias were identified due to the unclear randomization and blinding procedures reported. Additionally, there was a lack of data on several relevant clinical outcomes.

Abstract

BACKGROUND People with cystic fibrosis are at an increased risk of fat-soluble vitamin deficiency including vitamin E. Vitamin E deficiency can cause a host of conditions such as haemolytic anaemia, cerebellar ataxia and cognitive difficulties. Vitamin E supplementation is widely recommended in cystic fibrosis and aims to ameliorate this deficiency. This is an updated version of the review. OBJECTIVES To determine the effects of any level of vitamin E supplementation on the frequency of vitamin E deficiency disorders in people with cystic fibrosis. SEARCH METHODS We searched the Cochrane Group's Cystic Fibrosis Trials Register and also searched international trial registers for any ongoing clinical trials that were not identified during our register search.Date of last search of the Register: 10 October 2016. Date of last search of international trial registers: 15 February 2017. SELECTION CRITERIA Randomised controlled trials and quasi-randomised controlled trials comparing any preparation of vitamin E supplementation to placebo or no supplement, regardless of dosage or duration. DATA COLLECTION AND ANALYSIS Two authors extracted outcome data from each study (published information) and assessed the risk of bias of each included study. MAIN RESULTS Four studies with a total of 141 participants were included in the review, two of these were in children (aged six months to 14.5 years), and the other two did not specify participants' age. All studies used different formulations and doses of vitamin E for various durations of treatment (10 days to six months). Two studies compared the supplementation of fat-soluble as well as water-soluble formulations to no supplementation in different arms of the same study. A third study compared a water-soluble formulation to a placebo; and in the fourth study a fat-soluble formulation of vitamin E was assessed against placebo.At one month, three months and six months, water-soluble vitamin E significantly improved serum vitamin E levels compared with control: at one month, two studies, mean difference 17.66 (95% confidence interval 10.59 to 24.74); at three months, one study, mean difference 11.61 (95% confidence interval 4.77 to 18.45); and at six months, one study, mean difference 19.74 (95% confidence interval 13.48 to 26.00). At one month fat-soluble vitamin E significantly improved serum vitamin E levels compared with control: one month, two studies, mean difference 13.59 (95% CI 9.52 to 17.66). The findings at three months were imprecise; one study; mean difference 6.40 (95% confidence interval -1.45 to 14.25).None of the studies report the review's primary outcomes of vitamin E total lipid ratio or the incidence of vitamin E-specific deficiency disorders, or the secondary outcomes lung function or quality of life. Only one study, comparing water-soluble vitamin E with placebo, reported the secondary outcome of growth and nutritional status (weight), but the results are uncertain due to imprecision around the effect estimate.There was limited detail about randomisation and blinding in the included studies which compromises the quality of the evidence base for the review. The heterogeneous mix of the formulations with differing biovailabilities among these studies also limits the generalisability of the data to the wider cystic fibrosis population. AUTHORS' CONCLUSIONS Vitamin E supplementation led to an improvement in vitamin E levels in people with cystic fibrosis, although the studies may have been at risk of bias. No data on other outcomes of interest were available to allow conclusions about any other benefits of this therapy.In future, larger studies are needed, especially in people already being treated with enteric-coated pancreatic enzymes and supplemented with vitamin E, to look at more specific outcome measures such as vitamin E status, lung function and nutritional status. Future studies could also look at the optimal dose of vitamin E required to achieve maximal clinical effectiveness. show less