Supplementation of fish oil and olive oil in patients with rheumatoid arthritis

February 2005
Alair Alfredo Berbert M.D, Cacilda Rosa Mitiko Kondo M.D, Cecília Lisete Almendra M.D., Tiemi Matsuo Ph.D., Isaias Dichi M.D., Ph.D.

Abstract

Objective

This study evaluated whether supplementation with olive oil could improve clinical and laboratory parameters of disease activity in patients who had rheumatoid arthritis and were using fish oil supplements.

Methods

Forty-three patients (34 female, 9 male; mean age = 49 ± 19y) were investigated in a parallel randomized design. Patients were assigned to one of three groups. In addition to their usual medication, the first group (G1) received placebo (soy oil), the second group (G2) received fish oil ω-3 fatty acids (3 g/d), and the third group (G3) received fish oil ω-3 fatty acids (3 g/d) and 9.6 mL of olive oil. Disease activity was measured by clinical and laboratory indicators at the beginning of the study and after 12 and 24 wk. Patients' satisfaction in activities of daily living was also measured.

Results

There was a statistically significant improvement (P < 0.05) in G2 and G3 in relation to G1 with respect to joint pain intensity, right and left handgrip strength after 12 and 24 wk, duration of morning stiffness, onset of fatigue, Ritchie's articular index for pain joints after 24 wk, ability to bend down to pick up clothing from the floor, and getting in and out of a car after 24 wk. G3, but not G2, in relation to G1 showed additional improvements with respect to duration of morning stiffness after 12 wk, patient global assessment after 12 and 24 wk, ability to turn faucets on and off after 24 wk, and rheumatoid factor after 24 wk. In addition, G3 showed a significant improvement in patient global assessment in relation to G2 after 12 wk.

Conclusions

Ingestion of fish oil ω-3 fatty acids relieved several clinical parameters used in the present study. However, patients showed a more precocious and accentuated improvement when fish oil supplements were used in combination with olive oil.

Introduction

Beneficial effects of polyunsaturated ω-3 fatty acids are evident in many inflammatory conditions but are more evident in rheumatoid arthritis (RA) [1], [2], [3].

Several investigators have studied the effects of dietary fish oil supplements in patients with RA. Although improvement in some clinical parameters has been shown, especially in the number of tender joints [4], [5], [6], [7], [8], [9], duration of morning stiffness [4], [6], [9], [10], [11], [12], and, less frequently, handgrip strength [6], [8], [10], Ritchie's articular index [10], [13], patient global assessment [12], [13], medical global assessment [12], [14], intensity of pain [7], and onset of fatigue [5], the overall clinical response of fish oil supplement is considered modest [15].

Fish oil contains ω-3 polyunsaturated eicosapentaenoic acid (C20:5ω-3) and docosahexaenoic acid (C22:6ω-3). The inhibition of metabolites of arachdonic acid, especially its product through the 5-lipoxygenase pathway, leukotriene B4, is considered the most important mechanism of the action of ω-3 fatty acids.

Western diets contain large amounts of linoleic acid (C18:2ω-6), which is considered a proinflammatory fatty acid and contributes to the high ratio of ω-6 to ω-3 fatty acids verified in such diets [16]. This high ratio may have mitigated the more positive results expected with fish oil ω-3 fatty acids in patients with RA. However, a diet rich in monounsaturated fatty acids and oils rich in α-linolenic acid (C18:3ω-3) could overcome this issue [17].

Olive oil contains large amounts of oleic acid. Oleic acid is an ω-9 monounsaturated fatty acid (C18:1ω-9) that is converted to eicosatrienoic acid (ETA; C20:3ω-9). ETA is converted to LTA3, which is a potent inhibitor of leukotriene B4 synthesis [18]. Therefore, ETA may exert its anti-inflammatory action through a mechanism analogous to that of fish oil, which contains eicosapentaenoic acid.

Thus, the purpose of the present study was to verify whether modification of diet with olive oil could improve clinical and laboratory parameters of disease activity in patients who had RA and were using fish oil supplements.