REDUCED ASTHMA SYMPTOMS WITH N-3 FATTY-ACID INGESTION ARE RELATED TO 5-SERIES LEUKOTRIENE PRODUCTION

Asthma may respond to dietary modification, thereby reducing the need for pharmacologic agents. This study determined the effectiveness of n -3 polyunsaturated fatty acid (PUFA) ingestion in ameliorating methach oline-induced respiratory distress in an asthmatic population. The abi lity of urinary leukotriene excretion to predict efficacy of n-3 PUFA ingestion was assessed. After n-3 PUFAs in ratios to n-6 PUFAs of 0.1: 1 and 0.5:1 were ingested sequentially for 1 mo each; patient respirat ory indexes were assessed after each treatment. Forced vital capacity (FVC), forced expiratory volume for 1 s (FEV(1)), peak expiratory flow (PEF), and forced expiratory flow 25-75% (FEF(25-75)) were measured a long with weekly 24-h urinary leukotriene concentrations. With low n-3 PUFA ingestion, methacholine-induced respiratory distress increased. With high n-3 PUFA ingestion, alterations in urinary 5-series leukotri ene excretion predicted treatment efficacy. Elevated n-3 PUFA ingestio n resulted in a positive methacholine bronchoprovocation dose change i n > 40% of the test subjects (responders). The provocative dose to cau se a 20% reduction (PD20) in FEV(1), FVC, PEF, and FEF(25-75), values could not be calculated because of a lack of significant respiratory r eduction. Conversely, elevated n-3 PUFA ingestion caused some of the p atients (nonresponders) to further lose respiratory capacity. Five-ser ies leukotriene excretion with high n-3 PUFA ingestion was significant ly greater for responders than for nonresponders. A urinary ratio of 4 -series to 5-series leukotrienes < 1, induced by n-3 PUFA ingestion, m ay predict respiratory benefit.