Effects of altering dietary essential fatty acids on requirements for non-steroidal anti-inflammatory drugs in patients with rheumatoid arthritis: a double blind placebo controlled study.

Belch JJ, Ansell D, Madhok R, O'Dowd A, Sturrock RD.

Centre for Rheumatic Diseases, University Department of Medicine, Royal Infirmary.

In rheumatoid arthritis (RA) benefit from non-steroidal anti-inflammatory drugs (NSAIDs) is mediated through inhibition of the cyclo-oxygenase enzyme, thereby decreasing production of the 2 series prostaglandins (PGs).  The lipoxygenase enzyme is intact, however, allowing leucotriene (LT) production, e.g., LTB4 (an inflammatory mediator).  Treatment with evening primrose oil (EPO) which contains gamma-linolenic acid (GLA) leads to production of the 1 series PGs, e.g., PGE1, which has less inflammatory effects.  Also LT production is inhibited.  Eicosapentaenoic acid (EPA, fish oil) treatment provides a substrate for PGs and LTs, which are also less inflammatory.

In this study 16 patients with RA were given 540 mg GLA/day (EPO), 15 patients 240 mg EPA and 450 mg GLA/day (EPO/fish oil), and 18 patients an inert oil (placebo).  The aim of this study was to determine if EPO or EPO/fish oil could replace NSAID treatment in RA.  The initial 12 month treatment period was followed by three months of placebo for all groups.

Results at 12 months showed a significant subjective improvement for EPO and EPO/fish oil compared with placebo.  In addition, by 12 months the patients receiving EPO and EPO/fish oil had significantly reduced their NSAIDs.  After 3 months of placebo those receiving active treatment had relapsed.  Despite the decrease in NSAIDs, measures of disease activity did not worsen.  It is suggested that EPO and EPO/fish oil produce a subjective improvement and allow some patients to reduce or stop treatment with NSAIDs.  There is, however, no evidence that they act as disease modifying agents.