The absorption and effect of dietary supplementation with omega-3 fatty acids on serum leukotriene B4 in patients with cystic fibrosis

Long-term docosahexaenoic acid (DHA) supplementation in cystic fibrosis patients: a randomized, multi-center, double-blind, placebo-controlled trial

BACKGROUND

Cystic fibrosis (CF) patients have an alteration in fatty acid (FA) metabolism, associated with increased omega-6 and low omega-3 FA. Previous studies on supplementation with omega-3 FA in CF had contradictory results, and to date there is no evidence to recommend routine use of omega-3 supplements in CF patients. We hypothesized that long-term supplementation with docosahexaenoic acid (DHA) will have beneficial effects in these patients, by reducing pulmonary, systemic and intestinal inflammation.

METHODS

This was a randomized, double-blind, parallel, placebo-controlled trial. CF patients (age >2 months) were randomized to receive a seaweed DHA oil solution (50 mg/Kg/day) or matching placebo for 48 weeks. Primary outcomes were pulmonary (interleukin [IL]-8), systemic (IL-8) and intestinal (calprotectin) inflammatory biomarkers. Secondary outcomes included other pulmonary (IL-1β, IL-6, neutrophil elastase, lactate and calprotectin) and systemic (serum-IL-1β, IL-6) inflammatory biomarkers, as well as clinical outcomes (FEV₁, pulmonary exacerbations, antibiotic use, nutritional status and quality of life).

RESULTS

Ninety six CF patients, 44 female, age 14.6±11.9 years (48 DHA and 48 placebo) were included. At trial completion, there were no differences in all primary outcomes [serum-IL-8 (p=0.909), respiratory-IL-8 (p=0.384) or fecal calprotectin (p=0.948)], all secondary inflammatory biomarkers, or in any of the clinical outcomes evaluated. There were few adverse events, with similar incidence in both study groups.

CONCLUSION

In this study, long-term DHA supplementation in CF patients was safe, but did not offer any benefit on inflammatory biomarkers, or in clinical outcomes compared with placebo. (NCT01783613).

Influence of lung transplantation on the essential fatty acid profile in cystic fibrosis

Lung transplantation is assumed to normalize essential fatty acid (EFA) profile in the plasma, described as abnormal in patients with cystic fibrosis (CF). This study sought to evaluate the EFA profile in both the plasma and erythrocyte membrane according to lung status by comparing CF patients with or without a lung transplant. A total of 50 homozygous F508del patients (33 CF patients [CF group] and 17 CF patients with a lung transplant [TX CF group]) were included. In comparison with the CF group, in the plasma, the levels of total n-3, α-linolenic, eicosapentaenoic, and docosahexaenoic acids were higher and the n-6/n-3 ratio was lower in the TX CF group. Yet, these differences were not observed in the erythrocyte membrane. This study supports that lung transplantation improves the EFA profile in the plasma but not in the erythrocyte membrane by means of the different mechanisms suggested in this article.

Omega-3 fatty acid supplementation for cystic fibrosis

BACKGROUND

Studies suggest that a diet rich in omega-3 essential fatty acids may have beneficial anti-inflammatory effects for chronic conditions such as cystic fibrosis. This is an updated version of a previously published review.

OBJECTIVES

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

SEARCH METHODS

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. Date of last search: 01 April 2020. We also searched online study registries and contacted authors. Date of last search: 12 February 2020.

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

Two authors independently selected studies for inclusion, extracted data and assessed the risk of bias of the studies. The quality of the evidence was assessed using GRADE.

MAIN RESULTS

The searches identified 23 studies; five studies with 106 participants (children and adults) were included; duration of studies and interventions differed. Two studies compared omega-3 fatty acids to olive oil for six weeks; one study compared omega-3 fatty acids and omega-6 fatty acids to control capsules (customised fatty acid blends) for three months; one study compared a liquid dietary supplement containing omega-3 fatty acids to one without for six months; and one study compared omega-3 fatty acids to a placebo for 12 months. Three studies had a low risk of bias for randomisation, but the risk was unclear in the remaining two studies; all studies had an unclear risk of bias for allocation concealment. Three of the studies adequately blinded participants; the risk of bias for selective reporting was high in one study and unclear for four studies. Two studies reported the number of respiratory exacerbations. At three months, one study (43 participants) reported no change in antibiotic usage. At 12 months the second study (15 participants) reported a reduction in the number of pulmonary exacerbations and cumulative antibiotic days in the supplement group compared to the previous year (no data for the control group); very low-quality evidence means we are unsure whether supplementation has any effect on this outcome. With regards to adverse events, one six-week study (12 participants) reported no difference in diarrhoea between omega-3 or placebo capsules; the very low-quality evidence means we are unsure if supplementation has any effect on this outcome. Additionally, one study reported an increase in steatorrhoea requiring participants to increase their daily dose of pancreatic enzymes, but three studies had already increased pancreatic enzyme dose at study begin so as to reduce the incidence of steatorrhoea. One study (43 participants) reported stomach pains at three months (treatment or control group not specified). One six-week study (19 participants) reported three asthma exacerbations leading to exclusion of participants since corticosteroid treatment could affect affect essential fatty acid metabolism. Four studies reported lung function. One six-week study (19 participants) reported an increase in forced expiratory volume in one second (FEV₁) (L) and forced vital capacity (FVC) (L), but the very low-quality evidence means we are unsure if supplementation has any effect on lung function. The remaining studies did not report any difference in lung function at three months (unit of measurement not specified) or at six months and one year (FEV₁ % predicted and FVC % predicted). No deaths were reported in any of the five studies. Four studies reported clinical variables. One study reported an increase in Schwachman score and weight alongside a reduction in sputum volume with supplementation compared to placebo at three months (data not analysable). However, three studies reported no differences in either weight at six weeks, in body mass index (BMI) standard deviation (SD) score at six months (very low-quality evidence) or BMI Z score at 12 months. Three studies reported biochemical markers of fatty acid status. One study showed an increase from baseline in both EPA and DHA content of serum phospholipids in the omega-3 group compared to placebo at three months and also a significant decrease in n-6/n-3 ratio in the supplement group compared to placebo; since the quality of the evidence is very low we are not certain that these changes are due to supplementation. One six-month cross-over study showed a higher EPA content of the neutrophil membrane in the supplement group compared to the placebo group, but, no difference in DHA membrane concentration. Furthermore, the leukotriene B₄ to leukotriene B₅ ratio was lower at six months in the omega-3 group compared to placebo. A one-year study reported a greater increase in the essential fatty acid profile and a decrease in AA levels in the treatment arm compared to placebo.

AUTHORS' CONCLUSIONS

This review found that regular omega-3 supplements may provide some limited benefits for people with cystic fibrosis with relatively few adverse effects: however, the quality of the evidence across all outcomes was very low. The current evidence is insufficient to draw firm conclusions or recommend routine use of these supplements in people with cystic fibrosis. A large, long-term, multicentre, randomised controlled study is needed to determine any 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 when providing omega-3 supplementation or olive oil placebo capsules. More research is required to determine the exact dose of pancreatic enzyme required.

Antioxidant Micronutrients and Essential Fatty Acids Supplementation on Cystic Fibrosis Outcomes: A Systematic Review

BACKGROUND

Antioxidant micronutrients and essential fatty acids supplementation intake appears to have a protective effect in some diseases such as cardiovascular disease, cancer, and asthma.

OBJECTIVE

The aim of this study was to perform a systematic review to evaluate the effects of these nutrients on nutritional and clinical outcomes of patients with cystic fibrosis (CF).

METHODS

This is a systematic review of randomized clinical trials (RCTs) in CF. MEDLINE (via PubMed), Embase, and Scopus databases were searched for RCTs published from 1948 through February 2019. Two investigators independently reviewed the titles and abstracts and then extracted the data from the included studies using a standardized predesigned form. Two reviewers independently performed the quality assessment of the RCTs according to the Cochrane risk of bias tools.

RESULTS

A total of 4,792 studies were identified, and 23 were eligible (8 antioxidant micronutrient and 15 essential fatty acids). The interventions found were beta-carotene, zinc, magnesium, multivitamin, docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), linoleic acid and lipid matrix with choline supplementation. A significant improvement was observed in: (a) pulmonary function with magnesium (n=1) and essential fatty acids (n=2) supplementation; (b) less pulmonary exacerbations with beta-carotene (n=1), zinc (n=1), antioxidant-enriched multivitamin (n=1) and essential fatty acids (n=2) supplementation. One study with antioxidant-enriched multivitamin and four studies with EPA/DHA supplementation reported significant reductions in inflammatory markers. Nutritional status was not modified by antioxidants supplementation in any of the studies, while in five studies there was an improvement with fatty acids supplementation. The risk of bias of the majority of the parallel studies was high.

CONCLUSIONS

The benefits of antioxidants or DHA/EPA supplementation for CF, although observed in some studies, are not consistent enough to recommend routine use of these supplements. The mechanisms of action of these nutrients, dose levels and timing should be further explored in future studies.

Omega-3 Supplementation Improves Pruritus in Continuous Ambulatory Peritoneal Dialysis Patients: A Crossover Randomized Pilot Clinical Trial

Objective:

Pruritus is a prevalent skin condition in end-stage renal disease patients. Omega-3 fatty acids have been shown to reduce pruritus in hemodialysis patients. Our objective was to assess the effect of 3 g/day omega-3 supplementation on pruritus among continuous ambulatory peritoneal dialysis (CAPD) patients.

Methods:

In this two-period, two-sequence crossover randomized clinical trial, 40 eligible subjects (CAPD patients who complained of pruritus for more than 8 weeks) were randomized to 3 g of omega-3 (n = 20) or identical placebo capsules (n = 20) for 4 weeks. After a wash-out period of 6 weeks, patients were crossed over to the alternate treatment option. Pruritus intensity was assessed using the visual analog scale (VAS) at baseline, 2-and 4-weeks post-intervention in each study period. Both patients and investigators were blinded to the study protocol.

Findings:

No significant carry-over effect was detected. The mean pruritus score (VAS) in the omega-3 group compared with placebo group after the first (−3.02 vs. −0.48, P < 0.001) and second (−4.09 vs. −0.43, P < 0.001) intervention periods showed higher significant decrease.

Conclusion:

In summary, omega-3 supplementation is an effective treatment for pruritus alleviation in CAPD patients. Further studies are needed to determine the mechanisms underlying antipruritic effects of omega-3.

Elevated prostaglandin E metabolites and abnormal plasma fatty acids at baseline in pediatric cystic fibrosis patients: a pilot study

BACKGROUND

Airway inflammation is a significant contributor to the morbidity of cystic fibrosis (CF) disease. One feature of this inflammation is the production of oxygenated metabolites, such as prostaglandins. Individuals with CF are known to have abnormal metabolism of fatty acids, typically resulting in reduced levels of linoleic acid (LA) and docosahexaenoic acid (DHA).

METHODS

This is a randomized, double-blind, cross-over clinical trial of DHA supplementation with endpoints of plasma fatty acid levels and prostaglandin E metabolite (PGE-M) levels. Patients with CF age 6-18 years with pancreatic insufficiency were recruited. Each participant completed 3 four-week study periods: DHA at two different doses (high dose and low dose) and placebo with a minimum 4 week wash-out between each period. Blood, urine, and exhaled breath condensate (EBC) were collected at baseline and after each study period for measurement of plasma fatty acids as well as prostaglandin E metabolites.

RESULTS

Seventeen participants were enrolled, and 12 participants completed all 3 study periods. Overall, DHA supplementation was well tolerated without significant adverse events. There was a significant increase in plasma DHA levels with supplementation, but no significant change in arachidonic acid (AA) or LA levels. However, at baseline, AA levels were lower and LA levels were higher than previously reported for individuals with CF. Urine PGE-M levels were elevated in the majority of participants at baseline, and while levels decreased with DHA supplementation, they also decreased with placebo.

CONCLUSIONS

Urine PGE-M levels are elevated at baseline in this cohort of pediatric CF patients, but there was no significant change in these levels with DHA supplementation compared to placebo. In addition, baseline plasma fatty acid levels for this cohort showed some difference to prior reports, including higher levels of LA and lower levels of AA, which may reflect changes in clinical care, and consequently warrants further investigation.

Quality of Reporting Nutritional Randomized Controlled Trials in Patients With Cystic Fibrosis

OBJECTIVE

Randomized controlled trials (RCTs) have a major role in the making of evidence-based guidelines. The aim of the present study was to critically appraise the RCTs that addressed nutritional interventions in patients with cystic fibrosis.

METHODS

Embase, PubMed, and the Cochrane Library were systematically searched until July 2015. Methodology and reporting of nutritional RCTs were evaluated by the Consolidated Standards of Reporting Trials (CONSORT) checklist and additional dimensions relevant to patients with CF.

RESULTS

Fifty-one RCTs were included. Full details on methods were provided in a minority of studies. The mean duration of intervention was <6 months. 56.9% of the RCTs did not define a primary outcome; 70.6% of studies did not provide details on sample size calculation; and only 31.4% reported on the subgroup or separated between important subgroups.

CONCLUSIONS

The examined RCTs were characterized by a weak methodology, a small number of patients with no sample size calculations, a relatively short intervention, and many times did not examine the outcomes that are important to the patient. Improvement over the years has been minor.

The clinical benefits of long-term supplementation with omega-3 fatty acids in cystic fibrosis patients - A pilot study

Effectiveness of omega-3 supplementation in cystic fibrosis (CF) remains controversial. This study sought to evaluate clinical status, exercise tolerance, inflammatory parameters, and erythrocyte fatty acid profile after 1 year of oral omega-3 supplementation in CF patients. Fifteen ΔF508-homozygous patients undergoing chronic azithromycin were randomized to receive omega-3 fish oil supplementation at a dose of 60mg/Kg/day or placebo. In comparison with the previous year, in the supplemented group, the number of pulmonary exacerbations decreased at 12 months (1.7 vs. 3.0, p<0.01), as did the duration of antibiotic therapy (26.5 days vs. 60.0 days, p<0.025). Supplementation significantly increased the levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) as early as <3 months of administration, with concomitant decreases in arachidonic acid (AA) levels. This pilot study suggests that long-term omega-3 supplementation offers several clinical benefits as to the number of exacerbations and duration of antibiotic therapy in CF patients.

Omega-3 fatty acids for cystic fibrosis

BACKGROUND

Studies suggest that a diet rich in omega-3 essential fatty acids may have beneficial anti-inflammatory effects for chronic conditions such as cystic fibrosis. This is an updated version of a previously published review.

OBJECTIVES

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

SEARCH METHODS

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.Date of last search: 13 August 2013.

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

Two authors independently selected studies for inclusion, extracted data and assessed the risk of bias of the studies.

MAIN RESULTS

The searches identified 15 studies; four studies with 91 participants (children and adults) were included; duration of studies ranged from six weeks to six months. Two studies were judged to be at low risk of bias based on adequate randomisation but this was unclear in the other two studies. Three of the studies adequately blinded patients, however, the risk of bias was unclear in all studies with regards to allocation concealment and selective reporting.Two studies compared omega-3 fatty acids to olive oil for six weeks. One study compared a liquid dietary supplement containing omega-3 fatty acids to one without for six months. One study compared omega-3 fatty acids and omega-6 fatty acids to a control (capsules with customised fatty acid blends) for three months. Only one short-term study (19 participants) comparing omega-3 to placebo reported a significant improvement in lung function and Shwachman score and a reduction in sputum volume in the omega-3 group. Another study (43 participants) demonstrated a significant increase in serum phospholipid essential fatty acid content and a significant drop in the n-6/n-3 fatty acid ratio following omega-3 fatty acid supplementation compared to control. The longer-term study (17 participants) demonstrated a significant increase in essential fatty acid content in neutrophil membranes and a significant decrease in the leukotriene B4 to leukotriene B5 ratio in participants taking omega-3 supplements compared to placebo.

AUTHORS' CONCLUSIONS

This review found that regular omega-3 supplements may provide some benefits for people with cystic fibrosis with relatively few adverse effects, although evidence is insufficient to draw firm conclusions or recommend routine use of these supplements in people with cystic fibrosis. This review has highlighted the lack of data for many outcomes meaningful to people with or making treatment decisions about cystic fibrosis. A large, long-term, multicentre, randomised controlled study is needed to determine any 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.

Lung inflammation in cystic fibrosis: pathogenesis and novel therapies

Despite remarkable progress following the identification of the causing gene, the final outcome of cystic fibrosis (CF) remains determined mainly by the progressive reduction of lung function. Inflammation of the airways is one of the key elements of the pathogenesis of the disease: it is responsible for the destruction of lung architecture, resulting in progressive loss of respiratory function. Bronchial infection induces an intense inflammatory reaction characterized by a massive invasion of neutrophils, the properties of which seems altered in CF. Moreover, the inflammatory process is also marked by a profuse release of soluble pro-inflammatory mediators, such as interleukin (IL)-6, IL-1β and IL-8 cytokines. In contrast, release of the anti-inflammatory mediator IL-10 is reduced, thus reflecting a pro-/anti-inflammatory imbalance. The inflammation/infection pair seems hard to dissociate, and the origin of the baneful consequences of the persisting excessive inflammatory responses remains to be cleared up: does inflammation follow or rather precede infection? Recent data suggest that uncontrolled inflammation is constitutive in CF. Countering it at early stages of the disease in order to prevent irretrievable damages in lungs remains a major priority in treating patients with CF. In this review, we discuss the usefulness and limitations of mouse models of CF to study the pathogenesis of human lung inflammatory disease, and the development of new potential strategies to reduce the inflammatory burden in the airways.

Omega-3 fatty acids for cystic fibrosis

BACKGROUND

Studies suggest that a diet rich in omega-3 essential fatty acids may have beneficial anti-inflammatory effects for chronic conditions such as cystic fibrosis.

OBJECTIVES

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

SEARCH METHODS

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.Date of last search: 08 July 2013.

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

Two authors independently selected studies for inclusion, extracted data and assessed the risk of bias of the studies.

MAIN RESULTS

The searches identified 14 studies; four studies with 91 participants were included. Two studies were judged to be at low risk of bias based on adequate randomisation but this was unclear in the other two studies. Three of the studies adequately blinded patients, however, the risk of bias was unclear in all studies with regards to allocation concealment and selective reporting.Two studies compared omega-3 fatty acids to olive oil for six weeks. One study compared a liquid dietary supplement containing omega-3 fatty acids to one without for six months. One study compared omega-3 fatty acids and omega-6 fatty acids to a control (capsules with customised fatty acid blends) for three months. Only one short-term study (19 participants) comparing omega-3 to placebo reported a significant improvement in lung function and Shwachman score and a reduction in sputum volume in the omega-3 group. Another study (43 participants) demonstrated a significant increase in serum phospholipid essential fatty acid content and a significant drop in the n-6/n-3 fatty acid ratio following omega-3 fatty acid supplementation compared to control. The longer-term study (17 participants) demonstrated a significant increase in essential fatty acid content in neutrophil membranes and a significant decrease in the leukotriene B4 to leukotriene B5 ratio in participants taking omega-3 supplements compared to placebo.

AUTHORS' CONCLUSIONS

This review found that regular omega-3 supplements may provide some benefits for people with cystic fibrosis with relatively few adverse effects, although evidence is insufficient to draw firm conclusions or recommend routine use of these supplements in people with cystic fibrosis. This review has highlighted the lack of data for many outcomes meaningful to people with or making treatment decisions about cystic fibrosis. A large, long-term, multicentre, randomised controlled study is needed to determine any 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.

A randomized placebo-controlled study on high-dose oral algal docosahexaenoic acid supplementation in children with cystic fibrosis

Low plasma concentrations of docosahexaenoic acid (DHA) are reported in unsupplemented cystic fibrosis (CF) patients. Forty-one CF patients aged from 6 to 12 years were randomized to receive high-dose DHA (100 mg/kg/day in the first month and 1g per day thereafter through a 12-month supplementation) or placebo (germ oil). Primary outcome was percentage change in plasma AA:DHA ratio. Secondary outcomes were changes in the number of pulmonary exacerbations compared to previous year, lung function, BMI, skinfold thicknesses, and body composition assessed by DXA and in serum concentrations of C-reactive protein, cytokines and vitamin (α-tocopherol and retinol). Compared to the control group plasma AA:DHA ratio decreased in the intervention group after 6 months (median percentage changes: -73% in the intervention group vs. -10% in the control group, P=0.001). No differences were detected between groups for secondary outcomes. Despite a decrease of the AA/DHA ratio, DHA supplementation for one year did not induce any significant biochemical and clinical improvement in CF patients.

The Mediterranean diet: effects on proteins that mediate fatty acid metabolism in the colon

A Mediterranean diet appears to have health benefits in many domains of human health, mediated perhaps by its anti-inflammatory effects. Metabolism of fatty acids and subsequent eicosanoid production is a key mechanism by which a Mediterranean diet can exert anti-inflammatory effects. Both dietary fatty acids and fatty acid metabolism determine fatty acid availability for cyclooxygenase- and lipoxygenase-dependent production of eicosanoids, namely prostaglandins and leukotrienes. In dietary intervention studies and in observational studies of the Mediterranean diet, blood levels of fatty acids do reflect dietary intakes but are attenuated. Small differences in fatty acid levels, however, appear to be important, especially when exposures occur over long periods of time. This review summarizes how fat intakes from a Greek-style Mediterranean diet can be expected to affect fatty acid metabolizing proteins, with an emphasis on the metabolic pathways that lead to the formation of proinflammatory eicosanoids. The proteins involved in these pathways are ripe for investigation using proteomic approaches and may be targets for colon cancer prevention.

DHA and EPA reverse cystic fibrosis-related FA abnormalities by suppressing FA desaturase expression and activity

Patients and models of cystic fibrosis (CF) exhibit consistent abnormalities of polyunsaturated fatty acid composition, including decreased linoleate (LA) and docosahexaenoate (DHA) and variably increased arachidonate (AA), related in part to increased expression and activity of fatty acid desaturases. These abnormalities and the consequent CF-related pathologic manifestations can be reversed in CF mouse models by dietary supplementation with DHA. However, the mechanism is unknown. This study investigates this mechanism by measuring the effect of exogenous DHA and eicosapentaenoate (EPA) supplementation on fatty acid composition and metabolism, as well as on metabolic enzyme expression, in a cell culture model of CF. We found that both DHA and EPA suppress the expression and activity of Δ5- and Δ6-desaturases, leading to decreased flux through the n-3 and n-6 PUFA metabolic pathways and decreased production of AA. The findings also uncover other metabolic abnormalities, including increased fatty acid uptake and markedly increased retroconversion of DHA to EPA, in CF cells. These results indicate that the fatty acid abnormalities of CF are related to intrinsic alterations of PUFA metabolism and that they may be reversed by supplementation with DHA and EPA.

Omega-3 fatty acids for cystic fibrosis

BACKGROUND

Studies suggest that a diet rich in omega-3 essential fatty acids may have beneficial anti-inflammatory effects for chronic conditions such as cystic fibrosis.

OBJECTIVES

To determine whether there is evidence that omega-3 polyunsaturated fatty acid supplementation reduces morbidity and mortality and to identify any adverse events associated with 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.Date of last search: 10 March 2011.

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

Two authors independently selected studies for inclusion, extracted data and assessed the risk of bias of the studies.

MAIN RESULTS

The searches identified 13 studies; four studies with 91 participants were included. Two studies compared omega-3 fatty acids to olive oil for six weeks. One study compared a liquid dietary supplement containing omega-3 fatty acids to one without for six months. One study compared omega-3 fatty acids and omega-6 fatty acids to a control (capsules with customised fatty acid blends) for three months. Only one short-term study (19 participants) comparing omega-3 to placebo reported a significant improvement in lung function and Shwachman score and a reduction in sputum volume in the omega-3 group. Another study (43 participants) demonstrated a significant increase in serum phospholipid essential fatty acid content and a significant drop in the n-6/n-3 fatty acid ratio following omega-3 fatty acid supplementation compared to control. The longer-term study (17 participants) demonstrated a significant increase in essential fatty acid content in neutrophil membranes and a significant decrease in the leukotriene B4 to leukotriene B5 ratio in participants taking omega-3 supplements compared to placebo.

AUTHORS' CONCLUSIONS

This review found that regular omega-3 supplements may provide some benefits for people with cystic fibrosis with relatively few adverse effects, although evidence is insufficient to draw firm conclusions or recommend routine use of these supplements in people with cystic fibrosis. This review has highlighted the lack of data for many outcomes meaningful to people with or making treatment decisions about cystic fibrosis. A large, long-term, multicentre, randomised controlled study is needed to determine any 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.

Supplementation of N-3 LCPUFA to the diet of children older than 2 years: a commentary by the ESPGHAN Committee on Nutrition

The aim of this commentary is to review data on the effect of supplementation of paediatric patients ages 2 years or older with n-3 long-chain polyunsaturated fatty acids (LCPUFA). Some evidence for a positive effect on functional outcome in children with attention-deficit/hyperactivity disorder (ADHD) was found; however, benefit was seen in only about half of the randomised controlled trials (RCT), and studies varied widely not only in dose and form of supplementation but also in the functional outcome parameter tested. The committee concludes that there are insufficient data to recommend n-3 LCPUFA supplementation in the treatment of children with ADHD, but further research on n-3 LCPUFA supplementation in ADHD may be worthwhile. The committee was unable to find evidence of a favourable effect of n-3 LCPUFA supplementation on cognitive function in children. Although no benefit of n-3 LCPUFA supplementation was seen for major clinical outcome parameters in children with cystic fibrosis, a potentially beneficial shift towards less-inflammatory eicosanoid profiles seen in 2 studies provides grounds for further investigation; it is possible that earlier and longer supplementation periods may be needed to demonstrate clinical effect. For children with phenylketonuria, the limited data available suggest that supplementation of n-3 LCPUFA to the diet is both feasible and safe, but offers only transient benefit in visual function. For children with bronchial asthma there are insufficient data to suggest that LCPUFA supplementation has a beneficial effect. The committee advises paediatricians that most health claims about supplementation of n-3 LCPUFA in various diseases in children and adolescents are not supported by convincing scientific data.

Nutrition management of pediatric patients who have cystic fibrosis

Since the identification of cystic fibrosis (CF) in the 1940s, nutrition care of patients who have CF has been a challenge. Through optimal caloric intake and careful management of malabsorption, patients are expected to meet genetic potential for growth. Yet factors beyond malabsorption, including nutrient activity at the cellular level, may influence growth and health. This article reviews nutrition topics frequently discussed in relationship to CF and presents intriguing new information describing nutrients currently being studied for their impact on overall health of patients who have CF.

Lipid metabolism in cystic fibrosis

PURPOSE OF REVIEW

Expression of defective cystic fibrosis transmembrane conductance regulator (CFTR), the cause for cystic fibrosis, affects fatty acid, cholesterol and sphingolipid metabolism. This review summarizes recent observations and evaluates current understanding of mechanisms.

RECENT FINDINGS

Recent observations implicate CFTR, in addition to known effects on fatty acid and cholesterol metabolism, in the regulation of sphingolipid metabolism and suggest that this pathway is relevant to inflammation and infection. A common mechanism on how CFTR affects such a wide spectrum of lipid classes is currently not known. One mechanism for low linoleic acid, amenable to inhibition by docosahexaenoic acid, is increased metabolism in the n-6 fatty acid pathway. Accumulation of free cholesterol in distinct perinuclear compartments, reversible by overexpression of rab9, suggests that cystic fibrosis and the lysosomal storage disease Niemann-Pick-C could share similar cell signaling defects, in addition to increased cAMP signaling and sterol-regulatory element binding protein (SREBP) expression that affect cholesterol metabolism. Novel is the recognition that CFTR modulates ceramide mass and uptake of sphingosine-1- phosphate. Experiments in different cystic fibrosis-mouse models, although not able to establish whether ceramide mass is increased or decreased, suggest that normalization of ceramide decreases infection and selected parameters of inflammation, of relevance to the complex phenotype that characterizes cystic fibrosis.

SUMMARY

Expression of defective CFTR has profound effects on fatty acid, cholesterol and sphingolipid metabolism, for which mechanisms are currently poorly understood. Recent studies in different cystic fibrosis models suggest a causal relationship between altered ceramide mass and increased inflammation and susceptibility to infection. Studies in cystic fibrosis knockout mouse models suggest that normalization of ceramide decreases infection and inflammation. Studies that evaluate the diagnostic and clinical relevance of sphingolipids in patients with cystic fibrosis are needed.

Cystic Fibrosis and Nutrition: Linking Phospholipids and Essential Fatty Acids with Thiol Metabolism

Cystic fibrosis (CF) is the most common lethal inherited disorder among Caucasians and results from mutation in the gene encoding the CF transmembrane conductance regulator. In addition to its multisystem clinical effects, the disease is characterized by increased proinflammatory mediators and oxidant stress, and systemic redox imbalance with reduced glutathione (GSH), together with alterations in circulating and tissue (n-6) and (n-3) fatty acids, particularly a decrease in docosahexaenoic acid. The metabolism of phospholipids and fatty acids is closely related to GSH through the methionine-homocysteine cycle, in which choline via betaine provides methyl groups to regenerate S-adenosylmethionine, important in generating phosphatidylcholine and amino acid precursors for GSH. Current research focuses both on fatty acid supplementations to normalize altered (n-6) to (n-3) fatty acid balance and decrease generation of (n-6) fatty acid-derived inflammatory mediators, and strategies to improve oxidant defenses and redox balance. However, further research is needed before such strategies can be included in clinical care of individuals with CF.

Oral DHA supplementation in DeltaF508 homozygous cystic fibrosis patients

AIM

The aim of this study was to evaluate whether the previously observed changes in the fatty acid profile, as a result of DHA supplementation, could be maintained during longer study trials and to observe its effect on the clinical outcome of cystic fibrosis (CF) patients.

METHOD

A year-long double-blind placebo-controlled study was performed in DeltaF508 homozygous CF patients above the age of 6. Clinical data, including pulmonary function and number of infections, were collected. Blood for the determination of the fatty acid (FA) composition of serum phospholipid, vitamin E, liver enzymes, immunoglobulins, erythrocyte sedimentation rate and coagulation was drawn at the beginning and then every 6 months after the start of the study.

RESULTS

Seventeen patients were included; one dropped out. The treatment group was supplemented with an algal DHA-rich oil and the control group with sunflower seed oil. There was no difference between the control and treatment groups for W/H%, caloric intake, FEV1% and FVC% at the start of the study and after 1 year of supplements. The phospholipid FA composition did not change in the control group. The treatment group had a significant increase in DHA and eicosapentaenoic acid (EPA) concentration. A concomitant decrease of dihomo-gammalinolenic acid, arachidonic acid, 22:5 n-6 and Mead acid was observed. The laboratory results showed no changes in vitamin E level, liver enzymes, albumin, erythrocyte sedimentation rate and IgG concentration in either the placebo or the intervention group.

CONCLUSION

Although DHA-rich oil shifted the serum phospholipid FAs to a less pro-inflammatory profile, no conclusive clinical improvement could be observed so far.

Fatty acid alterations and n-3 fatty acid supplementation in cystic fibrosis

Specific fatty acid alterations have been described in the blood and tissues of cystic fibrosis (CF) patients. The two most consistent alterations include decreased levels of linoleic acid (LA) and decreased levels of docosahexaenoic acid (DHA). Increased arachidonic acid (AA) release from membrane phospholipids, as well as changes in levels of AA and other monounsaturated and polyunsaturated fatty acids (PUFAs) have also been described in CF. Although mechanisms of fatty acid alterations have not yet been determined, these alterations may have an important role in the progression of the CF disease. There have been several clinical trials in which CF patients were supplemented with n-3 fatty acids. Most trials resulted in an increase in the levels of the supplemental fatty acids in the blood of CF patients in the absence of significant clinical improvement. It is recommended that future trials include a larger population of CF patients and measure multiple clinical outcomes.

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

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: April 2007

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 the 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, weighted 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.

Fatty acids platelets and oxidative markers following intravenous n-3 fatty acids administration in cystic fibrosis: An open pilot observational study

BACKGROUND

An imbalance in the ratio of arachidonic acid and docosahexaenoic acid (DHA) was found in cystic fibrosis (CF) affected tissues and was suggested to promote inflammation. Several studies have shown that the long chain n-3 fatty acids reduced inflammatory activity while others have highlighted prooxidant activity of DHA at high concentrations. The aim of our study was to evaluate the effects of an intravenous fish-oil emulsion enriched with n-3 FA in patients with CF on plasma and platelet FA composition and peroxidation markers.

METHODS

13 patients with CF received one IV emulsion per week of 2 mL/kg fish-oil n-3 emulsion for 12 weeks.

RESULTS

There was a significant increase in 20:5 n-3 and 22:6 n-3 platelet FA composition, no variation in 20:4 n-6, a decrease in n-9. There was no variation in plasma FA composition. Specific urinary markers of lipid peroxidation derived from n-3 and n-6 showed a very high level before infusion compared with usual values in healthy subjects which was not affected by treatment. A significant weight loss and a decrease in reduced glutathione were observed in adult patients.

CONCLUSIONS

The intravenous administration of n-3 FA in CF patients induced a significant modification in platelet FA composition but no modification of oxidative markers. However, the weight loss and the decreased level in reduced glutathione observed in adult patients may suggest a potential deleterious activity for some patients. Further studies are necessary to determine the optimal dose and route for long chain FA administration required to reach a potential beneficial effect.

An overview of monitoring and supplementation of omega 3 fatty acids in cystic fibrosis

Essential fatty acid deficiency has been increasingly reported in patients with cystic fibrosis. The purpose of this work is to critically summarize previous data on fatty acid status and omega3 supplementation in cystic fibrosis. Although the reported abnormalities differ from study to study, the two most consistent features appeared to be reduced circulating levels of linoleic acid and docosahexaenoic acid (DHA). On the assumption that the fatty acid composition of erythrocyte cell membranes may be similar to that of other organs, it seems appropriate to monitor the phospholipid profile from erythrocyte membranes together with circulating blood levels. Formulations containing widely variable DHA doses, ranging from 300 mg to 5 g per day, have been administered to patients with cystic fibrosis with discrepant outcomes. Randomized controlled trials are needed in order to draw firm conclusions on the therapeutic effect of omega3 fatty acid supplementation in cystic fibrosis.

Current clinical applications of omega-6 and omega-3 fatty acids

BACKGROUND

Recent years have brought a resurgence of research interest in fatty acids, with studied fields running the gamut of human disease. This movement has run in parallel with an increased interest in using nutrition modalities as therapeutic measures, as opposed to their conventional role as energy sources. The aim of this manuscript is to provide a basic review of current clinical applications of omega-6 and omega-3 fatty acids, with a particular focus on the latter.

METHODS

A selective review of the voluminous literature, including randomized controlled trials, meta-analyses, population studies, and case reports, was used to compile data and identify trends in pertinent clinical applications of fatty acid therapy.

CONCLUSIONS

There are a myriad of disorders and maladies that seem to benefit from fatty acid supplementation, specifically omega-3 fatty acids. It has clearly been shown that omega-3 fatty acid supplementation provides a protective benefit in heart disease, and in particular sudden cardiac death. Rheumatoid arthritis (RA) is another disease entity that has been proven to benefit from this nutrition intervention, with improvement in symptoms and diminished nonsteroidal antiinflammatory drug (NSAID) usage. In addition, many psychiatric disorders, particularly schizophrenia and major depressive disorder (MDD), have shown positive results when supplementation has been used as an adjunct to standard pharmacotherapy. The remainder of clinical applications for omega-3 fatty acids requires further investigation. Specifically, according to preliminary clinical evidence, parenteral administration of fatty acids warrants further study.

Fatty acids in blood and intestine following docosahexaenoic acid supplementation in adults with cystic fibrosis

The objective of this study was to investigate the effect of docosahexaenoic acid (DHA) supplementation on blood and intestinal DHA levels and lung function in mild/moderately affected adult CF patients with the DeltaF508 genotype.

BACKGROUND

Cystic Fibrosis (CF) patients often present with plasma fatty acid levels indicating low levels of linoleic (18:2n-6) and docosahexaenoic (22:6n-3) acids and an increased level of arachidonic acid (20:4n-6). Improved dietary fat intake or reducing fat malabsorption with pancreatic enzymes has failed to normalize this biochemical deficiency of DHA.

METHODS

Five CF patients, aged 18-43, received 70 mg of DHA/kg body weight/d for six weeks. At baseline and at six weeks a physical exam, lung function, 3-day dietary intake, duodenal mucosal biopsy and blood sample were assessed. The blood was analyzed for plasma vitamin A, D and E levels, liver function tests, clinical chemistry (CBC, differential and electrolytes). Plasma and red blood cell fatty acid levels were also analyzed. At three weeks, assessment included a physical exam, lung function test and fasting blood sample (vitamin levels, liver function and clinical chemistry only).

RESULTS

Pre- and post-measurements were compared for the four subjects who completed the study. An increase in DHA content (% w/w) was observed in all phospholipid fractions of plasma, red blood cell and mucosal samples. No significant differences in vitamin levels, liver function or lung function were observed.

CONCLUSIONS

The study proves the concept that an increase in tissue DHA levels in CF patients can be achieved by supplementing for six weeks with 70 mg/kg/d DHA.

Biological effects of a dietary omega-3 polyunsaturated fatty acids supplementation in cystic fibrosis patients: a randomized, crossover placebo-controlled trial

BACKGROUND AND AIMS

Various anti-inflammatory therapies, including dietary omega-3 polyunsaturated fatty acids (PUFA) supplementation, have been investigated in cystic fibrosis (CF) patients. To further explore this nutritional approach, biological effects of an omega-3 PUFA oral liquid supplementation were measured in 17 CF patients in a double-blind, randomized, crossover without a washout period and placebo-controlled study.

METHODS

CF patients (age: 18+/-9 year; weight: 43+/-13 kg) received a liquid dietary supplementation either enriched or not in omega-3 PUFA (390-1170 mg/day according to patient weight) during two 6-month periods.

RESULTS

Increase in eicosapentaenoic acid was observed in neutrophil membrane following omega-3 PUFA dietary supplementation (from 0.7+/-0.6 to 1.6+/-0.6 micromol%, P<0.01). The leukotriene B(4) (LTB(4))/leukotriene B(5) (LTB(5)) ratio was decreased (from 72+/-27 to 24+/-7, P<0.001) in CF patients taking omega-3 PUFA supplements. In contrast, omega-3 PUFA supplementation affected neither internalization of IL-8 receptors following IL-8 exposure, nor IL-8-induced neutrophil chemotaxis.

CONCLUSION

Our results show that omega-3 PUFA are incorporated in neutrophil membranes. The subsequent decrease in LTB(4)/LTB(5) ratio suggests that, in such conditions, neutrophils may produce less pro-inflammatory mediators from the acid arachidonic pathway. These data indicate that omega-3 PUFA intake may have anti-inflammatory effect that still need to be assessed by long-term studies following large groups of patients.

Bioavailability and safety of a high dose of docosahexaenoic acid triacylglycerol of algal origin in cystic fibrosis patients: a randomized, controlled study

OBJECTIVE

Several studies have reported omega-3 and omega-6 fatty acid imbalances in patients with cystic fibrosis (CF). Whether these imbalances contribute to or are manifestations of the pathophysiology of CF is unknown. The study objective was to determine bioavailability, tissue accretion, and safety of a large dose of an algal source of docosahexaenoic acid (DHA) triacylglycerol and to observe effects on lung function in patients with CF.

METHODS

Twenty subjects with CF (8 to 20 y of age) were randomly assigned to receive algal oil providing 50 mg of DHA per kilogram per day (1 to 4.2 g of DHA per subject per day) or placebo for 6 mo. Fatty acids, liver enzymes, and lipid soluble antioxidants were measured in blood at baseline and at 1, 3, and 6 mo. Rectal biopsy specimens were collected at baseline and at 3 mo for fatty acid analysis. Lung function, anthropometrics, and adverse experiences were monitored throughout the study.

RESULTS

Compared with placebo, DHA supplementation increased plasma, erythrocyte, and rectal DHA levels four- to five-fold (P < 0.001) with concomitant decreases in blood arachidonic acid levels and the ratio of arachidonic acid to DHA. Supplementation was well tolerated, with no treatment-related changes in liver enzymes, growth, or antioxidant status. DHA supplementation had no detectable effect on lung function during the course of this study.

CONCLUSIONS

Algal DHA triacylglycerol oil is readily absorbed, well tolerated, and increases blood and tissue DHA levels in patients with CF. No adverse developments were associated with this large dose of DHA oil. Larger studies of longer duration are needed to determine whether DHA supplementation results in any clinically significant benefits in patients with CF.

Mechanisms of lipid malabsorption in Cystic Fibrosis: the impact of essential fatty acids deficiency

Transport mechanisms, whereby alimentary lipids are digested and packaged into small emulsion particles that enter intestinal cells to be translocated to the plasma in the form of chylomicrons, are impaired in cystic fibrosis. The purpose of this paper is to focus on defects that are related to intraluminal and intracellular events in this life-limiting genetic disorder. Specific evidence is presented to highlight the relationship between fat malabsorption and essential fatty acid deficiency commonly found in patients with cystic fibrosis that are often related to the genotype. Given the interdependency of pulmonary disease, pancreatic insufficiency and nutritional status, greater attention should be paid to the optimal correction of fat malabsorption and essential fatty acid deficiency in order to improve the quality of life and extend the life span of patients with cystic fibrosis.

Antiinflammatory Therapies for Cystic Fibrosis: Past, Present, and Future

Inflammation is a major component of the vicious cycle characterizing cystic fibrosis pulmonary disease. If untreated, this inflammatory process irreversibly damages the airways, leading to bronchiectasis and ultimately respiratory failure. Antiinflammatory drugs for cystic fibrosis lung disease appear to have beneficial effects on disease parameters. These agents include oral corticosteroids and ibuprofen, as well as azithromycin, which, in addition to its antimicrobial effects, also possesses antiinflammatory properties. Inhaled corticosteroids, colchicine, methotrexate, montelukast, pentoxifylline, nutritional supplements, and protease replacement have not had a significant impact on the disease. Therapy with oral corticosteroids, ibuprofen, and fish oil is limited by adverse effects. Azithromycin appears to be safe and effective, and is thus the most promising antiinflammatory therapy available for patients with cystic fibrosis. Pharmacologic therapy with antiinflammatory agents should be started early in the disease course, before extensive irreversible lung damage has occurred.

Is there a case for n-3 fatty acid supplementation in cystic fibrosis?

PURPOSE OF REVIEW

This review evaluates our current knowledge on the association of fatty acid abnormalities in cystic fibrosis with the disease process, and makes a case for a well-designed clinical trial to evaluate the clinical efficacy of long chain n-3 fatty acids.

RECENT FINDINGS

It has long been known that cystic fibrosis patients exhibit fatty acid abnormalities, but these have not been well investigated in tissues affected by the disease. Recent studies have demonstrated that such tissues do indeed show abnormalities in the proportions of linoleic, arachidonic and docosahexaenoic acids, and have demonstrated alterations in fatty acid and phospholipid metabolism in cystic fibrosis. Work in other areas has identified novel anti-inflammatory actions of long chain n-3 fatty acids that might be relevant to cystic fibrosis. A recent systematic review of fish oil supplementation in cystic fibrosis did not allow firm conclusions to be drawn, but suggested that there may be some benefits.

SUMMARY

The restoration of abnormal fatty acid profiles may be beneficial in cystic fibrosis, but this approach has not been evaluated in studies with a suitable design to permit firm conclusions to be drawn. There is a need for a long-term randomized controlled study to evaluate the therapeutic benefit of fish oil supplementation in cystic fibrosis.

Circulating markers to assess nutritional therapy in cystic fibrosis

Cystic fibrosis (CF) is the most commonly occurring lethal autosomal recessive disorder. The gene defect causes defective sodium and chloride transport across epithelial cells of the respiratory, hepatobiliary, gastrointestinal and reproductive tracts, resulting in thick mucus secretions. In the respiratory tract, mucus traps bacteria, causing repeated lung infections, progressive bronchiectasis and eventual death due to respiratory failure. In the gastrointestinal tract, mucus prevents pancreatic enzymes reaching the gut, leading to nutrient malabsorption. Careful nutritional management has a dramatic effect on growth and survival rates in CF. Appropriate nutritional support includes pancreatic enzyme replacement therapy, a high-fat/high-energy diet and essential nutrient supplementation, specifically fat-soluble vitamins and essential fatty acids (EFA). Long-term studies are required to examine the effects of nutritional interventions on key clinical outcomes in CF, such as the rate of decline of lung function. The use of circulating markers to assess the influence of nutritional therapy allows short-term intervention studies to predict the potential for clinical improvements. This article provides an overview of the biomarkers useful in the prediction of the efficacy of nutritional therapy on improvements in quality and quantity of life in CF.

Nutrition in patients with cystic fibrosis: a European Consensus

This document is the result of an European Consensus conference which took place in Artimino, Tuscany, Italy, in March 2001 involving 33 experts on nutrition in patients with cystic fibrosis, organised by the European Cystic Fibrosis Society, and sponsored by Axcan-Scandipharm, Baxter, Dr Falk Pharma, Fresenius, Nutricia, SHS International, Solvay Pharmaceuticals (major sponsor). The purpose of the conference was to develop a consensus document on nutrition in patients with cystic fibrosis based on current evidence.

High-performance liquid chromatography/electrospray ionization ion-trap tandem mass spectrometric analysis and quantification of phosphatidylcholine molecular species in the serum of cystic fibrosis subjects supplemented with docosahexaenoic acid

Since phosphatidylcholine (PC) is the most abundant phospholipid (PL) class in human serum, its concentration represents an important marker for the evaluation of lipid absorption and metabolism. High-performance liquid chromatography coupled on-line with electrospray ionization ion-trap tandem mass spectrometry (HPLC/ESI-MS/MS) was successfully applied to the quantitative analysis of PC molecular species from serum of cystic fibrosis (CF) subjects before and after supplementation with docosahexaenoic acid (DHA). Seven molecular species of PC (containing C16:0/C20:4, C16:0/C22:6, C18:0/C20:4, C18:0/C22:6, C16:0/C18:1, C16:0/C18:2 and C18:0/C18:2, respectively) were quantified using MS in the negative scan mode with 1,2-diundecanoyl-sn-glycero-phosphocholine as the internal standard. The molecular species containing DHA, C16:0/C22:6 and C18:0/C22:6, increased from 41.3 +/- 31.7 and 33.1 +/- 18.2 to 85.4 +/- 20.4 and 52.1 +/- 20.7 microg/mL serum, respectively, after a 3-month supplementation. Interestingly, the species containing arachidonic acid (C18:0/C20:4 and C16:0/C20:4) decreased from 115 +/- 55 and 139 +/- 57 to 58.1 +/- 22.5 and 70.5 +/- 28.1, respectively. HPLC/ESI-MS/MS allowed the direct analysis of the lipid extract without previous purification of PLs, thus it is a useful analytical support in CF research in order to understand the extent of lipid dysfunctions typical of CF or other diseases. The present method might also be used for quantitative analysis of each serum phospholipid class molecular species. However, the instrument response was found to be very dependent on the phospholipid class considered, and thus the use of appropriate standards for each class of PLs is recommended.

Hypothesis: vitamin E complements polyunsaturated fatty acids in essential fatty acid deficiency in cystic fibrosis

While several studies have demonstrated essential fatty acid (EFA) deficiency in plasma and tissue lipids of cystic fibrosis (CF) patients, the reasons for this deficiency are not well established. It is believed that reduced EFA intake, malabsorption of fat, altered desaturase/lipase activity and defective cystic fibrosis transmembrane conductance regulator (CFTR) altering utilisation of EFA in epithelial cells contribute to the development of EFA deficiency in CF. It is likely that increased metabolism of arachidonic acid to eicosanoids such as leukotrienes, thromboxane and prostaglandins may also be a contributing factor. Evidence is presented that elevated oxidative damage to EFA and impaired antioxidant defences, in particular vitamin E, may contribute to the development of EFA deficiency in CF. Furthermore, antioxidant supplementation in CF may improve EFA status.

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

BACKGROUND

Epidemiological (population studies) 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.

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 specialised trials register, which comprises references identified from comprehensive electronic database searches, handsearching relevant journals and handsearching abstract books of conference proceedings. Authors and persons interested in the question were contacted. Date of the most recent search of the Group's specialised register: May 2002.

SELECTION CRITERIA

Randomised controlled trials in patients with cystic fibrosis in which omega-3 fatty acid supplements were compared with a placebo oil.

DATA COLLECTION AND ANALYSIS

Two reviewers independently selected the trials to be included in the review and assessed the methodological quality of the trials using two approaches: Cochrane assessment of allocation concealment and Jadad quality assessment score. Using data acquisition forms, two reviewers independently extracted data. Missing data has been requested.

MAIN RESULTS

The initial literature search identified six trials. Two trials, involving 31 participants satisfied our inclusion criteria and were included in the review. Both compared omega-3 fatty acids to olive oil controls for a six week treatment period. One study (19 participants) showed an improvement in FEV1, FVC, Shwachman score and reduction in sputum volume in the fish oil group at the end of this short treatment period.

REVIEWER'S CONCLUSIONS

The review of trials found that regular omega-3 supplements may provide some benefits for people with cystic fibrosis with relatively few adverse effects, although the evidence is insufficient to draw firm conclusions. There is insufficient evidence to recommend routine use of supplements of omega-3 fatty acids in people with cystic fibrosis. The most notable feature highlighted by this review was 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, multi-centre, 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.

Role of polyunsaturated fatty acids in lung disease

DF Horrobin hypothesized that the low prevalence of lung disease among Eskimos is the result of their diet, which is high in n-3 fatty acids. The n-3 and n-6 fatty acids shunt eicosanoid production away from the arachidonic acid pathway, and hence decrease the production of bronchoconstrictive leukotrienes. Animal studies showed that eicosapentaenoic acid or gamma-linolenic acid supplementation of animals exposed to endotoxins results in decreased effects on thromboxane B(2) and pulmonary vascular resistance. Small human trials confirmed that supplementation with eicosapentaenoic acid results in increased eicosapentaenoic acid in phospholipids and decreased generation of leukotrienes by neutrophils. Hence, a protective effect of such fatty acids in lung disease is biologically plausible. The results of human intervention studies looking at respiratory outcomes have been mixed, but they do suggest a possible difference between long-term and short-term effects. Epidemiologic studies showed possible protective effects against asthma in children, but weak to no evidence of such effects in adults. Results for bronchitis are more positive, although intervention trials are lacking. Recently, a cross-sectional analysis of data from the first National Health and Nutrition Examination Survey reported an approximately 80-mL difference in forced expiratory volume at 1 s between adults with high compared with low fish consumption. This response was not limited to asthmatic subjects. Others found that both fish consumption and n-3 fatty acid consumption (as estimated from food-frequency questionnaires) were protective against physician-diagnosed emphysema and chronic bronchitis and low spirometry values. Only smokers were included in this analysis. These results suggest that dietary fatty acids may play a role in lung disease; further work is needed to elucidate that role.

A membrane lipid imbalance plays a role in the phenotypic expression of cystic fibrosis in cftr(-/-) mice

A deficiency in essential fatty acid metabolism has been reported in plasma from patients with cystic fibrosis (CF). However, its etiology and role in the expression of disease is unknown. The objective of this study was to determine whether alterations in fatty acid metabolism are specific to CF-regulated organs and whether they play a role in the expression of disease. A membrane lipid imbalance was found in ileum, pancreas, and lung from cftr(-/-) mice characterized by an increase in phospholipid-bound arachidonic acid and a decrease in phospholipid-bound docosahexaenoic acid (DHA). This lipid imbalance was observed in organs pathologically affected by CF including lung, pancreas, and ileum and was not secondary to impaired intestinal absorption or hepatic biosynthesis of DHA. As proof of concept, oral administration of DHA to cftr(-/-) mice corrected this lipid imbalance and reversed the observed pathological manifestations. These results strongly suggest that certain phenotypic manifestations of CF may result from remediable alterations in phospholipid-bound arachidonic acid and DHA levels.

The future potential of eicosanoids and their inhibitors in paediatric practice

Eicosanoids may have many potential uses in paediatric practice. Since E-type prostaglandins were first applied to treat ductus-dependent congenital heart diseases in paediatric practice, many eicosanoid-related drugs have been examined for the treatment of pathophysiological conditions in children. Prostaglandins (PG), thromboxane (TX) and leukotrienes (LT), produced from arachidonic acid in the phospholipids of cell membranes, are considered to be biologically active eicosanoids. Corticosteroids reduce eicosanoid production by impairing phospholipase A2 activation, while cyclo-oxygenase inhibiting drugs such as the nonsteroidal anti-inflammatory drugs (NSAID) suppress PG and TX production. PGE1 (alprostadil) and PGE2 (dinoprostone) therapy has been shown to improve oxygenation in neonates whose pulmonary and systemic blood flow are dependent on a patent ductus arteriosus, while epoprostenol (prostacyclin, PGI2) and beraprost (beraprost sodium), another PGI2 analogue, are often effective as acute vasodilators in paediatric pulmonary hypertension. Synthetic PGE analogues such as misoprostol have gastric antisecretory and cytoprotective effects, and are effective in both prophylaxis and treatment of NSAID-induced gastroduodenal mucosal lesions. Both alprostadil and epoprostenol have been shown to be effective in treating peripheral vascular and skin diseases. Since TX, a platelet aggregator and vasoconstrictor, has been implicated as a potential mediator of asthma, its inhibition by agents such as seratrodast (AA-2414) and ozagrel (OKY-046) has proven effective in the treatment of adult patients with asthma; studies of these agents in paediatric patients is awaited with interest. Developing the clinical use of eicosanoid-related drugs and assessing the potential use of these drugs requires a 3-phase approach: reducing the complications in the treatment of neonates with ductus-dependent congenital heart diseases and primary pulmonary hypertension requiring PGE1, PGE2 and PGI2 therapy; conducting clinical trials of the synthesis inhibitors and receptor antagonists of TXA2 and LT that have already been used in the treatment of adult patients with bronchial asthma; and evaluating the efficacy of new modulators of eicosanoid biosynthesis, such as eicosapentaenoic acid and antiallergy drugs, in the treatment of eicosanoid-related diseases in children.

The effect of 12 months' treatment with eicosapentaenoic acid in five children with cystic fibrosis

Five children with cystic fibrosis (CF) and chronic suppurative lung disease had eicosapentaenoic acid (EPA) supplementation for 12 months. Outcome was measured by the change in frequency of admissions/bed days while taking EPA compared to the previous 2 years. Although no significant changes occurred, there is an indication that this treatment may benefit children who don't have end-stage disease. Further studies are indicated in the use of this neglected mode of treatment.