Abstract/Summary

Although high dose omega-3 polyunsaturated fatty acid (n-3 PUFA) supplementation reduces exercise- and hyperpnoea-induce bronchoconstriction (EIB/HIB), there are concurrent issues with cost, compliance, and gastrointestinal discomfort. It is thus pertinent to establish the efficacy of lower n-3 PUFA doses. Eight male adults with asthma and HIB and 8 controls without asthma were randomly supplemented with two n-3 PUFA doses (6.2 g/d (3.7g EPA and 2.5g DHA)and 3.1 g/d (1.8g EPA and 1.3g DHA)) and a placebo, each for 21 days followed by 14 days washout. A eucapnic voluntary hyperpnoea (EVH) challenge was performed before and after treatments. Outcome measures remained unchanged in the control group. In the HIB group, the peak fall in forced expiratory volume in 1 s (FEV1) after EVH at day 0 (-1005 (SD 520) mL, -30 (SD 18) %) was unchanged after placebo. The peak fall in FEV1 was similarly reduced from day 0 to day 21 of 6.2 g/d n-3 PUFA (-1000 (SD 460) mL, -29 (SD 17) % vs. -690 (SD 460) mL, -20 (SD 15) %) and 3.1 g/d n-3 PUFA (-970 (SD 480) mL, -28 (SD 18) % vs. -700 (SD 420) mL, -21 (SD 15) %) (P<0.001). Baseline fraction of exhaled nitric oxide was reduced by 24% (P=0.020) and 31% (P = 0.018) after 6.2 and 3.1 g/d n-3 PUFA, respectively. Peak increases in 9α, 11ß PGF2 after EVH were reduced by 65% (P=0.009) and 56% (P=0.041) after 6.2 and 3.1 g/d n-3 PUFA,respectively. In conclusion, 3.1 g/d n-3 PUFA supplementation attenuated HIB and markers of airway inflammation to a similar extent as a higher dose. Lower doses of n-3 PUFA thus represent a potentially beneficial adjunct treatment for adults with asthma and EIB.