Evening primrose oil supplementation leads to an elevation of DGLA, which is a competitive inhibitor of pro-inflammatory PGs and leukotrienes, and therefore results in a reduced inflammatory response (Belch & Hill 2000). As such, EPO supplements have been investigated in the management of RA, with both negative and positive results (Belch et al 1988, Brzeski et al 1991, Hansen et al 1983, Jantti et al 1989, Veale et al 1994, Zurier et al 1996).
In one 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 initial 12-month treatment period was followed by 3 months' placebo for all groups. Results at 12 months showed a significant subjective improvement for EPO and EPO/fish oil compared with placebo. Additionally, within 12 months the patients receiving EPO and EPO/fish oil had significantly reduced their NSAID intake. After > 2007 Elsevier Australia
3 months' 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 (Belch et al 1988).
In a randomised, single-blind placebo-controlled trial (Zurier et al 1996), treatment with 2.8 g/day GLA resulted in a significant and clinically relevant reduction in RA symptoms and signs of disease activity. GLA therapy demonstrated a significant improvement in swollen joint count and score, tender joint count and score, duration of morning stiffness, patient's global assessment, patient's assessment of pain and degree of disability compared with baseline (measured by Health Assessment Questionnaire score). Not all of these parameters were significantly improved compared with placebo, but this may be due to the choice of safflower oil as a placebo. Olive oil, which contains oleic acid, also found in safflower oil, has been reported in other studies to benefit patients with RA (Brzeski et al 1991).
In one group of patients who were treated with GLA for 12 months, 16 of 21 showed meaningful improvement and 7 patients were able to decrease their NSAID and/or prednisolone dosage. GLA does not have a disease-modifying effect and supplementation must be long term. After 3 months without GLA supplementation, most patients were experiencing an exacerbation of symptoms. GLA was well tolerated during the trial with only three minor adverse reactions reported. Complete blood count and platelet count did not show abnormal results (Zurier et al 1996).
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