Serum n3 polyunsaturated fatty acids are depleted in Crohn's disease.

To determine fatty acid patterns in Crohn's disease, we measured various serum fatty acids by gas chromatography in 20 patients with the disease and compared them with those in 18 healthy controls. All the patients had been free from any nutritional supplementation during preceding six months or had no history of intestinal resection. Eight of the patients were affected in the small bowel only, three in the large bowel only, and the remaining nine in both the small and large bowel. Both serum concentrations and percentages of C20:4n6, C20:5n3, C22:0, C22:6n3, total n3 polyunsaturated fatty acids, and total polyunsaturated fatty acids were lower in the patients than in the controls. Both essential fatty acids (C18:2n6, C18:3n3) and C20:3n9 levels were not different between the two groups. Among nine fatty acids that correlated with the Crohn's disease activity index, C20:5n3 and total n3 polyunsaturated fatty acids showed the most significant negative correlations. These findings suggest that essential fatty acid deficiency rarely occurs in Crohn's disease and also that n3 polyunsaturated fatty acids may be relevant to the activity of the disease.