Omega-3 fatty acids (from fish oils) for cystic fibrosis

  • Review
  • Intervention

Authors


Abstract

Background

Epidemiological and other studies suggest that a diet rich in omega-3 essential fatty acids (derived from fish oil) may have beneficial anti-inflammatory effects for chronic conditions such as cystic fibrosis (CF).

Objectives

To determine whether there is evidence that omega-3 polyunsaturated fatty acid supplementation reduces morbidity and mortality. To identify any adverse events associated with omega-3 polyunsaturated fatty acid supplementation.

Search strategy

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. Authors and persons interested in the subject of the review were contacted.

Most recent search: June 2008.

Selection criteria

Randomised controlled trials in people with CF comparing omega-3 fatty acid supplements with placebo.

Data collection and analysis

Two authors independently selected studies for inclusion in the review, independently extracted data and assessed the methodological quality of the studies.

Main results

Searches identified seven studies; three of which, involving 48 participants, were eligible for inclusion in the review. Two studies compared omega-3 fatty acids to olive oil controls for a six-week treatment period. One study compared omega-3 fatty acids in the form of a liquid dietary supplement containing polyunsaturated fatty acids to a liquid dietary supplement control for six months. One short-term study (19 participants) comparing omega-3 to placebo reported a significant improvement in forced expiratory volume in one second, forced vital capacity and Shwachman score and a reduction in sputum volume in the omega-3 group. The longer-term study (17 participants) demonstrated a significant increase in essential fatty acid content in neutrophil membranes in study participants taking omega-3 supplements compared to placebo, mean difference 0.90 (95% confidence interval 0.46 to 1.34).

Authors' conclusions

This review found that regular omega-3 supplements may provide some benefits for people with CF with relatively few adverse effects, although the evidence is insufficient to draw firm conclusions or to recommend routine use of supplements of omega-3 fatty acids in people with CF. This review has highlighted the lack of data for many of the outcomes likely to be meaningful to people with or making treatment decisions about CF. A large, long-term, multicentre, randomised controlled study is needed in order to determine if there is a significant therapeutic effect and to assess the influence of disease severity, dosage and duration of treatment. Future researchers should note the need for additional pancreatic enzymes.

Plain language summary

There is not enough evidence on the safety and effectiveness of fish oil supplements for people with cystic fibrosis to recommend routine supplementation

Cycles of infection and inflammation are believed to exacerbate lung damage in people with cystic fibrosis. Fish oils are the richest dietary source of omega-3 fatty acids, which studies suggest may be anti-inflammatory and benefit many chronic inflammatory diseases including cystic fibrosis. This review includes three small studies of omega-3 supplements compared to placebo. One short-term study reported significant improvement in lung function and clinical status and a reduction in sputum volume when taking omega-3 supplements. Another longer study showed a significant increase in essential fatty acid content of neutrophil membranes in participants taking omega-3 supplements. Few adverse effects were reported in any of the studies. We conclude that regular omega-3 supplements may benefit people with CF with few adverse effects. However, there is insufficient evidence to draw firm conclusions or recommend routine use of these supplements in people with cystic fibrosis from the three small studies included in this review. Larger and longer trials are needed to assess the clinical benefit of fish consumption or fish oil supplementation and to determine appropriate dosage.