Eur Respir J, 1998, Volume 11; Issue 2: Pages 261 - 265.

Effect of dietary intake of omega-3 and omega-6 fatty acids on severity of asthma in children.

Hodge, L. Salome, CM. Hughes, JM. Liu-Brennan, D. Rimmer, J. Allman, M et al.

Key Findings

This study involved a randomized controlled trial in which the diets of asthmatic children were supplemented with either omega -3 or omega-6 fatty acids. The effects on clinical, biochemical and inflammatory parameters were measured over 6 months. Circulating eosinophil numbers and TNFα production continued to fall at 6 months in the present study even though changes in omega-3 fatty acids in the plasma phospholipids were maximal at 3 months. A fish oil supplement along with the addition to the diet of canola oil and canola oil margarine (high ALA) over 6 months increased the plasma levels of omega-3 fatty acids, but had no effect on the clinical severity of asthma in these children. However, there was a downward trend in both eosinophil numbers and tumour necrosis factor α production in the omega-3 group. This suggests that increases in dietary omega-3 fatty acids over a longer period of time may be required to reduce the severity of existing asthma.

ABSTRACT

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, randomized, 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 α (TNFα) 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 TNFα 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 α production, but had no effect on the clinical severity of asthma in these children.

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