The Effect of Conjugated Linoleic Acid Supplementation on the Severity of Exercise-Induced Bronchoconstriction

Abstract

Listen

Translate article

PURPOSE: The aim of this study was to investigate the effect of conjugated linoleic acid (CLA) supplementation on the severity of exercise-induced bronchoconstriction (EIB) in asthmatic subjects. METHODS: Six subjects with physician-diagnosed asthma and EIB participated in an intervention trial for 8 weeks. Subjects entered the study on their normal diet, after which they received 6 tablets containing 4.8 g CLA·day-1 for 8 weeks. Pulmonary function tests were administered pre- and post-eucapnic voluntary hyperventilation (EVH) challenge at the commencement (Week 0) and at the conclusion of the study period (Week 8). Pre- and 90 minutes post-EVH challenge urine samples were collected and assayed for the presence of cysteinyl leukotrienes (LT) C4-E4 and 9a, 11b-prostaglandin (PG) F2. Diet was monitored pre- and post-CLA supplementation using a Food Frequency Questionnaire (FFQ). RESULTS: Mean percent change in post-EVH forced expiratory volume in one second (FEV1) did not significantly differ (p>0.05) at any time point from Week 0 to Week 8. Mean maximum percent change in post-EVH FEV1 at Week 8 (-29.6 ± 16.2%) was not significantly different (p>0.05) when compared to Week 0 (-32.0 ± 13.4%). Area under the curve of FEV1 plotted against time from zero to 60 minutes (AUC0-60) remained unaltered at Week 8 (-931.1 ± 857.2 % change·min) compared to Week 0 (-1089.6 ± 661.3 % change·min). Similar patterns were observed for forced mid-expiratory flow (FEF25-75%), forced vital capacity (FVC), and FEV1/FVC. Additionally, post-EVH urinary LTC4-E4 and 9a, 11b-PGF2 levels were not significantly different (p>0.05) as a result of the CLA supplementation (LTC4-E4: 99.1 ± 90.4 ng·mmol creatinine-1 and 121.2 ± 88.6 ng·mmol creatinine-1 at Week 0 and Week 8, respectively; 9a, 11b-PGF2: 95.4 ± 51.6 ng·mmol creatinine-1 and 138.7 ± 73.3 ng·mmol creatinine-1 at Week 0 and Week 8, respectively). CONCLUSIONS: This study has shown that CLA supplementation does not attenuate airway inflammation or EIB in asthmatic individuals in response to an EVH challenge. Supported by a grant from The Gatorade Sports Science Institute and product donation from Cognis.