Treatment of asthma with lipid extract of New Zealand green-lipped mussel: a randomised clinical trial Protective effect of fish oil supplementation on exercise-induced bronchoconstriction in asthma. Effect of dietary intake of omega-3 and omega-6 fatty acids on severity of asthma in children. Dietary supplementation with fish oil rich in omega-3 polyunsaturated fatty acids in children with bronchial asthma. Effect of a fish oil diet on asthma: results of a 1-year double-blind study. Effect of dietary supplementation with fish oil lipids on mild asthma. The feasibility of creating a checklist for the assessment of the methodological quality both of randomised and non-randomised studies of health care interventions. Dietary fish oil effects on seasonal hay fever and asthma in pollen-sensitive subjects. Effects of dietary supplementation with n-3 fatty acids compared with n-6 fatty acids on bronchial asthma. Evening primose oil and fish oil are ineffective as supplementary treatment of bronchial asthma. The effects of dietary supplementation with fish oil lipids on the airways response to inhaled allergen in bronchial asthma.
Asthma is a chronic inflammatory disease of the airways mediated , at least in part , by leukotrienes and other lipid mediators . Experimental studies have shown that lipid extract of New Zeal and green-lipped mussel , Perna canaliculus , is effective in inhibiting 5′-lipoxygenase and cyclo-oxygenase pathways responsible for production of eicosanoids , including leukotrienes and prostagl and ins . The aim of this study was to assess its effect on symptoms , peak expiratory flow ( PEF ) and hydrogen peroxide ( H2O2 ) in expired breath condensate as a marker of airway inflammation in patients with steroid-naïve atopic asthma in a double-blind r and omised , placebo-controlled clinical trial . Forty six patients with atopic asthma received two capsules of lipid extract ( Lyprinol ® ) or placebo b.i.d . for 8 weeks . Each capsule of lipid extract contained 50 mg ω-3 polyunsaturated fatty acids and 100 mg olive oil , whereas placebo capsules contained only 150 mg olive oil . There was a significant decrease in daytime wheeze , the concentration of exhaled H2O2 and an increase in morning PEF in the lipid extract group compared to the placebo group . There were no significant side-effects . The authors conclude that lipid extract of New Zeal and green-lipped mussel may have some beneficial effect in patients with atopic asthma BACKGROUND Previous research has demonstrated that fish oil supplementation has a protective effect on exercise-induced bronchoconstriction ( EIB ) in elite athletes , which may be attributed to its antiinflammatory properties . Since EIB in asthma involves proinflammatory mediator release , it is feasible that fish oil supplementation may reduce the severity of EIB in asthmatic subjects . STUDY OBJECTIVES To determine the efficacy of fish oil supplementation on severity of EIB in subjects with asthma . DESIGN R and omized , double-blind , crossover study . SETTING Lung function and exercise testing in a university research laboratory . PATIENTS AND MEASUREMENTS Sixteen asthmatic patients with documented EIB entered the study on their normal diet  and then received either fish oil capsules containing 3.2 g of eicosapentaenoic acid and 2.0 g of docohexaenoic acid ( fish oil diet , n = 8) or placebo capsules ( placebo diet , n = 8) daily for 3 weeks . At the beginning of the study ( normal diet ) and at the end of each treatment phase , the following pre-exercise and postexercise measures were assessed : ( 1 ) pulmonary function ; ( 2 ) induced sputum differential cell count percentage and proinflammatory eicosanoid metabolite ( leukotriene C4 [LTC4]-leukotriene E4 [ LTE4 ] and prostagl and in D2 [ PGD2 ] ) and cytokine ( interleukin [IL]-1beta and tumor necrosis factor [TNF]-alpha ) concentrations ; and ( 3 ) eicosanoid metabolites leukotriene B4 ( LTB4 ) and leukotriene B5 ( LTB(5 ) ) generation from activated polymorphonuclear leukocytes ( PMNLs ) . RESULTS On the normal and placebo diet , subjects exhibited EIB . However , the fish oil diet improved pulmonary function to below the diagnostic EIB threshold , with a concurrent reduction in bronchodilator use . Induced sputum differential cell count percentage and concentrations of LTC4-LTE4 , PGD2 , IL-1beta , and TNF-alpha were significantly reduced before and following exercise on the fish oil diet compared to the normal and placebo diets . There was a significant reduction in LTB4 and a significant increase in LTB5 generation from activated PMNLs on the fish oil diet compared to the normal and placebo diets . CONCLUSION Our data suggest that fish oil supplementation may represent a potentially beneficial nonpharmacologic intervention for asthmatic subjects with EIB We assessed the clinical and biochemical effects in asthmatic children of fish oil supplementation and a diet that increases omega-3 and reduces omega-6 fatty acids . Thirty nine asthmatic children aged 8 - 12 yrs participated in a double-blind , r and omized , controlled trial for 6 months during which they received fish oil capsules plus canola oil and margarine ( omega-3 group ) or safflower oil capsules plus sunflower oil and margarine ( omega-6 group ) . Plasma fatty acids , stimulated tumour necrosis factor alpha ( TNFalpha ) production , circulating eosinophil numbers and lung function were measured at baseline and after 3 and 6 months of dietary modification . Day and night symptoms , peak flow rates and medication use were recorded for 1 week prior to laboratory visits . Plasma phospholipid omega-3 fatty acids were significantly greater in the omega-3 group at 3 and 6 months compared to the omega-6 group ( p<0.001 ) . In the omega-3 group TNFalpha production fell significantly compared with baseline ( p=0.026 ) , but the magnitude of change between groups did not reach significance ( p=0.075 ) . There were no significant changes in clinical outcome measures . Dietary enrichment of omega-3 fatty acids over 6 months increased plasma levels of these fatty acids , reduced stimulated tumour necrosis factor alpha production , but had no effect on the clinical severity of asthma in these children Omega-3 polyunsaturated fatty acids have anti-inflammatory effects in vitro , and high dietary levels are associated with a lower incidence of inflammatory diseases . However , only limited effects have been demonstrated in asthma . The effects of dietary supplementation with fish oil for 10 months in 29 children with bronchial asthma was investigated in a r and omized controlled fashion . In order to minimize the effects of environmental inhaled allergens and diet , this study was performed in a long-term treatment hospital . Subjects received fish oil capsules containing 84 mg eicosapentaenoic acid ( EPA ) and 36 mg docosahexaenoic acid ( DHA ) or control capsules containing 300 mg olive oil . The daily dosages of EPA and DHA were 17.0 - 26.8 and 7.3 - 11.5 mg x kg body weight(-1 ) , respectively . Asthma symptom scores decreased and responsiveness to acetylcholine decreased in the fish oil group but not in the control group . In addition , plasma EPA levels increased significantly only in the fish oil group ( p<0.0088 ) . No significant side-effects were observed . The present results suggest that dietary supplementation with fish oil rich in the omega-3 polyunsaturated fatty acids eicosapentaenoic acid and docosahexaenoic acid is beneficial for children with bronchial asthma in a strictly controlled environment in terms of inhalant allergens and diet Airway inflammation is a major component of asthma . Food intake of N-3 fatty acids ( FA ) is associated with a low incidence of inflammatory diseases , such as asthma . We treated 12 asthmatic patients with  FA  and report the positive results of this 1-year double-blind study . A positive effect on forced expiratory volume in 1 s was observed after the 9 month of treatment . Our results are in favor of the use of FA , but have to be confirmed by other studies Recruitment of inflammatory leucocytes to the airways may play a part in the pathogenesis of asthma . As dietary enrichment with fish oil lipids can suppress leucocyte function , the effect of these lipids on asthma control and neutrophil function was studied in 20 subjects with mild asthma . Twelve subjects received capsules containing 3.2 g of eicosapentaenoic acid and 2.2 g of docosahexaenoic acid daily and eight subjects received placebo capsules containing olive oil for 10 weeks in a double blind fashion . Baseline specific airways conductance , airways responsiveness to histamine and exercise , diurnal peak expiratory flow , symptom scores , and bronchodilator use were measured . Neutrophil fatty acid composition was evaluated by gas chromatography , calcium ionophore induced neutrophil leukotriene (LT)B4 and LTB5 generation were measured by reverse phase high performance liquid chromatography and radioimmunoassay , and neutrophil chemotactic responses to formyl-methionyl-leucyl-phenylalanine ( FMLP ) and LTB4 were assessed by a microchemotaxis technique . Although the fish oil supplemented diet produced a greater than 10 fold increase in the eicosapentaenoic acid content of neutrophil phospholipids , there was no significant change in airways responsiveness to histamine or any change in any of the clinical measurements . After dietary supplementation with fish oil there was a 50 % inhibition of total LTB ( LTB4 + LTB5 ) generation by ionophore stimulated neutrophils and neutrophil chemotaxis was substantially suppressed . Neutrophil function remained unchanged in the placebo group . It is concluded that in subjects with mild asthma a fish oil enriched diet attenuates neutrophil function without changing the severity of asthma OBJECTIVE : To test the feasibility of creating a valid and reliable checklist with the following features : appropriate for assessing both r and omised and non-r and omised studies ; provision of both an overall score for study quality and a profile of scores not only for the quality of reporting , internal validity ( bias and confounding ) and power , but also for external validity . DESIGN : A pilot version was first developed , based on epidemiological principles , review s , and existing checklists for r and omised studies . Face and content validity were assessed by three experienced review ers and reliability was determined using two raters assessing 10 r and omised and 10 non-r and omised studies . Using different raters , the checklist was revised and tested for internal consistency ( Kuder-Richardson 20 ) , test-retest and inter-rater reliability ( Spearman correlation coefficient and sign rank test ; kappa statistics ) , criterion validity , and respondent burden . MAIN RESULTS : The performance of the checklist improved considerably after revision of a pilot version . The Quality Index had high internal consistency ( KR-20 : 0.89 ) as did the subscales apart from external validity ( KR-20 : 0.54 ) . Test-retest ( r 0.88 ) and inter-rater ( r 0.75 ) reliability of the Quality Index were good . Reliability of the subscales varied from good ( bias ) to poor ( external validity ) . The Quality Index correlated highly with an existing , established instrument for assessing r and omised studies ( r 0.90 ) . There was little difference between its performance with non-r and omised and with r and omised studies . Raters took about 20 minutes to assess each paper ( range 10 to 45 minutes ) . CONCLUSIONS : This study has shown that it is feasible to develop a checklist that can be used to assess the method ological quality not only of r and omised controlled trials but also non-r and omised studies . It has also shown that it is possible to produce a checklist that provides a profile of the paper , alerting review ers to its particular method ological strengths and weaknesses . Further work is required to improve the checklist and the training of raters in the assessment of external validity The effects of taking 18 capsules a day of Max-EPA ( 3.2 g/day eicosapentaenoic acid ) on clinical symptoms and bronchial hyperresponsiveness were studied in pollen-sensitive subjects over a pollen season in a parallel , double-blind , placebo-controlled ( olive oil ) fashion . The study was conducted over the 1990 and 1991 pollen seasons in London , Engl and . A total of 37 nonsmoking pollen-sensitive asthmatic subjects were entered into the trial , and 25 completed the 6-month study period over the 2 yr . The preseasonal geometric mean PD35 SGaw of histamine for the fish oil ( n = 12 ) and placebo ( n = 9 ) groups were 0.62 and 0.42 mumol , respectively . During the middle of the pollen season , histamine PD35 SGaw fell significantly for both the fish oil ( 0.11 mumol , p < 0.0001 ) and placebo groups ( 0.10 mumol , p < 0.007 ) , indicating increased bronchial reactivity compared with preseasonal values , but there was no significant difference between the groups . Similarly , morning and evening peak expiratory flow ( PEF ) , diurnal variability in PEF , nocturnal cough and wheeze , daytime wheeze , and activity , as well as nasal symptoms and increased usage of medication , were not significantly different between the groups . Compliance was confirmed by neutrophil and plasma phospholipid analysis , which showed significant rises in eicosapentaenoic acid content in the fish oil group but not in the placebo group . We conclude that dietary fish oil supplementation does not prevent seasonal hay fever and asthma in pollen-sensitive subjects during the pollen season OBJECTIVE The effects of perilla seed oil ( n-3 fatty acids ) on bronchial asthma were compared with the effects of corn oil ( n-6 fatty acids ) in relation to the pulmonary function and the generation of leukotriene B4 ( LTB4 ) and C4 ( LTC4 ) by leucocytes . METHODS AND SUBJECTS 14 asthmatic subjects were divided r and omly into two groups : one group ( 7 subjects ) consumed perilla seed oil-rich supplementation and the other group ( 7 subjects ) consumed corn oil-rich supplementation for 4 weeks .  Generation of LTs by leucocytes and respiratory function were compared between the two groups . RESULTS The generation of LTB4 and LTC4 by leucocytes tended to increase in subjects ( N=7 ) with corn oil-rich supplementation , and decrease in subjects ( N=7 ) with perilla seed oil-rich supplementation . Significant differences between the two groups were observed in the generation of LTB4 at 2 weeks ( p<0.05 ) and LTC4 at 2 weeks ( p<0.05 ) after dietary supplementation . Significant increases in the value of PEF ( p<0.05 ) , FVC ( p<0.01 ) , FEV(1.0 ) ( p<0.05 ) and V(25 ) ( p<0.05 ) were found in subjects who received perilla seed oil supplementation for 4 weeks . And significant differences in the value of FVC ( p<0.05 ) and FEV(1.0 ) ( p<0.05 ) were observed between the two groups after 4 weeks of dietary supplementation . CONCLUSION These results suggest that perilla seed oil-rich supplementation is useful for the treatment of asthma in terms of suppression of LTB4 and LTC4 generation by leucocytes , and improvement of pulmonary function The effect of daily dietary supplementation with 15 to 20 mL of evening primrose seed oil or fish oil was assessed by comparison with olive oil as placebo in a cross-over study in 29 asthmatics . During 10 weeks of each regimen , the patients kept record of symptoms , peak expiratory flow rates and medication . Plasma and urine TxB2 , PGE2 , PGF2 alpha and 6 keto-PGF1 alpha and plasma fatty acid composition of plasma cholesterol esters were measured at the end of each treatment period . There were no differences between regimes with regard to peak flow rates , symptoms , or drug consumption . Plasma PGE2 levels increased during the fish oil treatment but there were no changes in other prostanoids in plasma or urine . The fatty acid pattern of plasma cholesterol esters showed significant differences between the supplementation periods . We conclude that moderate doses of evening primrose oil or fish oil are ineffective as a supplementary treatment of bronchial asthma The effects of dietary supplementation with fish oil lipids on the airways responses to allergen and neutrophil biochemistry and function have been studied in 17 atopic asthmatic subjects . Nine subjects received 18 capsules of Max-EPA ( 3.2 g eicosapentaenoic acid and 2.2 g docosahexaenoic acid ) a day and eight subjects received identical capsules containing olive oil , for 10 wk in a double-blind fashion . There were no differences between prediet values and those observed after dietary supplementation with Max-EPA or placebo in the dose of allergen causing an acute asthmatic response as assessed by a 35 % fall in specific airways conductance ( PD35 ) , the extinction dose of allergen on skin prick testing , the histamine PD35 , or the total serum IgE concentrations . Twelve of the 17 subjects developed late asthmatic responses after allergen challenge prediet . Six of these subjects received Max-EPA , and six received placebo capsules . As compared to prediet values , the magnitude of the allergen-induced late asthmatic response was significantly attenuated from 2 to 7 h after allergen challenge following dietary supplementation with Max-EPA ( p less than 0.005 ) but not with placebo . The attenuation of the late response was not accompanied by any significant change in the clinical severity of disease as assessed by diurnal peak expiratory flow rates , symptom scores , or bronchodilator drug usage . ( ABSTRACT TRUNCATED AT 250 WORDS
Background Considerable interest exists in the potential therapeutic value of dietary supplementation with the omega-3 fatty acids .
Given the interplay between pro-inflammatory omega-6 fatty acids , and the less pro-inflammatory omega-3 fatty acids , it has been thought that the latter could play a key role in treating or preventing asthma .
The purpose was to systematic ally review the scientific-medical literature in order to identify , appraise , and synthesize the evidence for possible treatment effects of omega-3 fatty acids in asthma .