Background: Rheumatic joint pain is a common extra-intestinal complication of inflammatory bowel disease (IBD). Because the high ratio of n-6 to n-3 fatty acids (FAs) of the Western diet might promote rheumatic disorders, we sought to compare the effects of short-term duodenal administration of n-3-rich seal oil and n-6-rich soy oil on IBD-related joint pain.
Methods: Nineteen patients with IBD-related joint pain were included in the study; 9 had Crohn disease and 10 had ulcerative colitis. Ten millilitres seal oil (n = 10) or soy oil (n = 9) was self-administered through a nasoduodenal feeding tube 3 times daily for 10 days.
Results: Compared with soy oil treatment, seal oil significantly reduced the duration of morning stiffness (P = 0.024), number of tender joints (P = 0.035), intensity of pain (P = 0.025) and the doctor's scoring of rheumatic disease activity (P = 0.025) at the end of the 10-day treatment period. Analysis of the effects as area under the curve (area between the curve and baseline, zero) for the entire period from start of treatment until 6 months' post-treatment suggested a long-lasting beneficial effect of seal oil administration on joint pain, whereas soy oil tended (not significantly) to aggravate the condition. Consistently, the serum ratios of n-6 to n-3 FAs (P < 0.01) and arachidonic acid to eicosapentaenoic acid (P < 0.01) were reduced after treatment with seal oil.
Conclusion: The results suggest distinctive, differential prolonged effects on IBD-related joint pain of short-term duodenal administration of n-3-rich seal oil (significant improvement) and n-6-rich soy oil (tendency to exacerbation).